Electrician TT 2nd Year (set 1)By pulak.univ / February 1, 2024 Welcome to CBT Exam Preparation - Fitter (2nd Year) Try to repeatedly answer the questions till you get the CORRECT answers LET'S CONTINUE 1. What is the name of the part marked as ‘X’ in DC generator? Add description here! Armature core Brush Commutator raiser Commutator segment None 2. What is the name of D.C generator? Add description here! Differential long shunt compound Differential short shunt compound Cumulative long shunt compound Cumulative short shunt compound None 3. Which rule is used to find the direction of induced emf in D.C generator? Cork screw rule Right hand palm rule Fleming’s left-hand rule Fleming’s right hand rule None 4. Which formula is used to calculate the generated emf in D.C generator? None 5. What is the formula to calculate back emf of a D.C motor None 6. What is the name of the D.C generator? Add description here! Shunt generator Series generator Compound generator Separately excited generator None 7. Which energy is converted into electrical energy by generator? Heat Kinetic Chemical Mechanical None 8. What is the name of D.C generator field? Add description here! Short shunt compound generator Long shunt compound generator Differential compound generator Cumulative compound generator None 9. What is the principle of D.C generator? Cork screw rule Fleming’s left-hand rule Fleming’s right hand rule Faradays laws of electromagnetic induction None 10. What is the formula for dynamically induced emf? BLV volts BL sinθ volts BLV sinθ volts BLV cosθ volts None 11. Which rule is used to find direction of magnetic field? Cork screw rule Right hand palm rule Fleming’s left hand rule Fleming’s right hand rule None 12. What is the name of the part of DC generator? Add description here! Stator Pole core Pole shoes Yoke (or) frame None 13. How many parallel paths in duplex lap winding of a 4 pole DC generator? 4 6 8 12 None 14. How interpoles are connected in a DC generator? In series with armature In parallel with armature In series with shunt field In parallel with shunt field None 15. What is the necessity of residual magnetism in a self excited DC generator? Build up the voltage Reduce the field current Reduce armature current Maintain constant output voltage None 16. None 17. Which are the two points that the brush contact resistance measured in D.C machines? Resistance between the opposite brushes Resistance between brush and commutator raiser Resistance between brush and commutator Resistance between brush and armature conductors None 18. Which voltage drop is indicated in the portion marked as X? Add description here! Full load voltage drop Armature voltage drop Armature reaction drop Shunt field voltage drop None 19. What is the name of the compound generator, if the shunt field is connected in parallel with armature? Long shunt compound Cumulative compound Differential compound Short shunt compound None 20. None 21. Why the armature core of a DC generator is laminated? Reduce the copper loss Reduce the friction loss Reduce the hysteresis loss Reduce the eddy current loss None 22. Why armature resistance of a D.C generator is very low? Reduce armature current Reduce armature voltage drop Run armature with less weight Reduce the temperature of armature None 23. Why the D.C generator should run in clockwise direction only? Protect brushes from damage Protect the residual magnetism Avoid short circuit in armature Avoid over loading of generator None 24. Why compensating winding is provided in large DC generators? Connect more loads Reduce commutation effect Neutralize armature reaction effect Increase the efficiency of generator None 25. What is the reason for DC generator fails to build up voltage? Loose brush contact Armature resistance is more Field resistance is above critical resistance Prime mover is running at above rated speed None 26. What is the name of generator, if its field is connected in parallel with armature? Shunt generator Series generator Compound generator Self excited generator None 27. What is the purpose of pole shoe in DC generator? Reduce the air gap Increase the field strength Minimize the magnetic losses Spread out flux uniformly in the air gap None 28. What is the function of split rings in DC generator? Maintain constant voltage Collects the current unidirectionally Reduces the voltage drop at brushes Increases the terminal voltage than rated None 29. Which material is used to make brush in generator? Steel and graphite Carbon and graphite Cast iron and graphite Aluminium and graphite None 30. Why DC generators are loosing their residual magnetism? Heavy short circuit in load Running without load continuously Continuous running without break Change of direction of rotation very often None 31. How does the magnetic circuit complete through the yoke and poles in a generator? Field coils Armature core Laminated pole core Winding conductors in armature None 32. Why the terminal voltage decreases if load increases in DC shunt generator? Because of armature reaction effect Due to increased in armature resistance Because of brush voltage drop decreases Due to increased in shunt field inductance None 33. Which type of DC generator is used for long distance distribution lines? Shunt generator Series generator Differential compound generator Cumulative compound generator None 34. Which method is used to improve the insulation resistance in DC generator? Replacing the brushes frequently Heating the machine by running periodically Cleaning the commutator segments regularly Blowing hot air in to the machine during maintenance None 35. Which type of D.C Generator works in absence of residual magnetism? Shunt generator Series generator Compound generator Separately excited generator None 36. Which type of D.C generator is used for arc welding? Shunt generator Series generator Differential compound generator Cumulative compound generator None 37. What is the property of wave winding in D.C generator? Low current low voltage High current low voltage Low current high voltage High current high voltage None 38. What is the purpose of resistance wire used in the commutator connection in D.C generator? Add description here! Maintain constant voltage Nullifying statically induced emf Increasing statically induced emf Smooth reversal of current direction None 39. Why solid pole shoes are used in D.C generator? To reduce the copper loss To increase the residual magnetism To decrease the residual magnetism To reduce the reluctance of magnetic path None 40. Which metal is used to make large capacity DC generator yoke? Cast iron Soft iron Aluminium Rolled Steel None 41. What is the function of split rings in a D.C generator? Supplies output continuously Makes output in the uni direction Makes output in the opposite direction Collects the output from alternate conductors None 42. Which type of voltage is induced dynamically in a D.C generator? Pulsating voltage Oscillating voltage Alternating voltage Direct current voltage None 43. What is the purpose of slot marked as ‘X’? Add description here! To fix the key way To make air circulation For lubrication purpose For easy removal from shaft None 44. What is the purpose of field coils in D.C generator? To increase the flux in air gap To decrease the magnetizing current To magnetize the poles to produce coil flux To increase the reluctance of magnetic path None 45. Which metal is used to make pole core of large DC generator machines? Soft iron Cast iron Cast steel Stainless steel None 46. Why the pole core stampings are laminated in DC generator? Reduce the friction loss Reduce the windage loss Reduce the hysteresis loss Reduce the eddy current loss None 47. What is the purpose of compensating winding in DC generator? Minimizes rough commutation Maintain constant output voltage Neutralizes the demagnetizing effect Decreases the excitation current of field coils None 48. What is the effect if the shunt field resistance is above critical resistance value in a D.C generator? Output voltage is pulsating Output voltage is above normal Generator fails to build up voltage Generator builds up voltage normally None 49. What is the effect of armature reaction in DC generator? Output voltage increases Output voltage decreases | Output voltage is pulsating Output voltage will become zero None 50. Calculate the emf generated in a 4 pole DC generator with simplex wave wound armature has 1020 conductors and driven at a speed of 1500 rpm, the flux / pole is 0.007 webers? 178 V 243 V 357 V 428 V None 51. How the effect of armature reaction can be neutralized in large DC generators? Using compensating winding Providing additional inter poles Increasing brush contact resistance Adding resistance wires with winding None 52. What is the effect in D.C generator, if it is kept ideal for long time? Field coil resistance increases Armature resistance increases Increase the armature reaction Looses its residual magnetism None 53. Calculate the induced emf of 4 pole dynamo having 1000 rpm lap wound and total number of conductors is 600, the flux / pole is 0.064 wb? | 160V 320V 480V 640V None 54. What is the effect on induced emf if the main field flux get distorted in DC generator? Induced emf increases Induced emf decreases No change in induced emf Induced emf becomes zero None 55. What is the cause for heavy sparking in brushes of DC generator? Short circuit in field winding Short circuit in armature winding MNA and GNA position changed Too much spring tension at brush None 56. Which instrument is used to measure armature winding resistance? Megger Multimeter Series type Ohm meter Kelvin bridge None 57. Which instrument is used to test armature winding for short and open circuit? Tong Tester Internal Growler External Growler Digital multimeter None 58. What is the name of the speed control method of DC motor? Field diverter method Field tapping method Voltage control method Armature diverter method None 59. Which winding wire is used for DC field coil? Super enamelled copper wire Single silk covered copper wire Double silk covered copper wire PVC covered copper winding wire None 60. Which formula is used to calculate the speed of DC motor? None 61. How many parallel paths in duplex lap winding in the armature of 4 pole D.C Motor? 2 4 6 8 None 62. Which rule determines the direction of rotation of armature in D.C motor? Right hand grip rule Right hand palm rule Fleming’s left hand rule Fleming’s right hand rule None 63. What is the name of D.C motor? D.C shunt motor D.C series motor D.C differential compound motor D.C cumulative compound motor None 64. Which rule determines the direction of current in D.C motor? Right hand grip rule Right hand palm rule Fleming’s left hand rule Fleming’s right hand rule None 65. None 66. Which rule is applied to identify the direction of flux in DC motor? Cork’s screw rule Right hand grip rule Fleming’s left hand rule Fleming’s right hand rule None 67. Name the type of DC motor. Add description here! Shunt motor Series motor Long shunt compound motor Short shunt compound motor None 68. What is the formula to calculate back EMF in a DC motor? None 69. What is the name of the equipment? Add description here! Megger Earth resistance tester Internal growler External growler None 70. What is the name of winding, if coil pitch is less than pole pitch? Full pitch winding Half pitch winding Long chorded winding Short chorded winding None 71. What is the purpose of series resistor connected with holding coil in a D.C four point starter? Limit the current in holding coil Increase the current in holding coil Increase the voltage in holding coil Decrease the voltage in holding coil None 72. Which speed control method of D.C series motor is used for electric train? Field diverter method Field tapping method Armature diverter method Supply voltage control method None 73. Why shunt field coil is connected in series with holding coil in D.C three point starter? Increase the holding coil current Decrease the holding coil current Protect the shunt field from over current Protect the motor in case of open in shunt field None 74. Why the direction of rotation is changed only by changing the armature current direction in a D.C compound motor? Maintain rated speed Maintain motor characteristics Avoid armature reaction effect Prevent motor from over loading None 75. Which speed control methods offers below normal speed in DC shunt motor? Field control method Voltage control method Armature control method Ward Leonard system of speed control | None 76. Why starters are required to start D.C motors in industries? Regulate the field voltage Reduce the armature current Control the armature reaction Smooth operation of motors None 77. Which insulating material belongs to class ‘B’ insulation? Cotton Bamboo Fiber glass Leatheroid paper None 78. What is the temperature value of class ‘F’ insulation? 90°C 105°C 120°C 155°C None 79. Which type of D.C motor is used for constant speed drives? DC series motor DC shunt motor Differential long shunt compound motor Differential short shunt compound motor None 80. Which type of DC motor is used in elevators? DC series motor DC shunt motor DC differential compound motor DC cumulative compound motor None 81. Which method of speed control gives below the rated speed in DC series motor? Field diverter method Tapped field method Voltage control method Armature diverter method None 82. What is the effect, if a four point starter resistance is cutoff during running? Motor stopped Runs at slow speed Runs at very high speed Runs at reverse direction None 83. Why carbon composition brush requires in the armature circuit to operate the D.C motor? Increases the starting torque Protects from armature reaction Protects armature from over loading Reduces the spark in the commutator segment None 84. Why series motor produce high torque and speed initially without load? Absence of back emf Load current flows through field winding Armature current and field current are same Series field winding wound with thick wire None 85. Why the series field is short circuited at the time of starting in differential compound motor? To reduce the starting current To increase the speed of motor To decrease the speed of motor To maintain proper direction of rotation None 86. Which is the most effective method of balancing armature? Static balancing Dynamic balancing Attached with counter balancing Plugged with lead weight balancing None 87. Which material is used for starting resistance of DC starters? Eureka Nichrome Manganin Constantine None 88. Which DC compound motor is operated at constant speed under varying load? Differential long shunt Cumulative long shunt Differential short shunt Cumulative short shunt None 89. How No volt coil is connected in a three point starter with DC shunt motor? Directly connected to supply Connected in series with armature Connected in parallel with armature Connected in series with shunt field None 90. Which type of armature winding is illustrated? Add description here! Duplex lap winding Triplex lap winding Simplex lap winding Quadruplex lap winding None 91. None 92. Which growler test for armature is illustrated? Add description here! Open coil test Grounded coil test Shorted coil test Shorted commutator test None 93. Which speed control method is applied to obtain both below normal and above normal speed in DC motor? Field control method Armature control method Tapped field speed control Ward Leonard speed control None 94. Why commutators are sparking heavily? Incorrect brush position Incorrect field connection Incorrect direction of rotation Incorrect armature connection None 95. What is the action of the induced emf in a running D.C motor? Assists the applied voltage Opposes the applied voltage Increases the armature current Decreases the armature current None 96. Which motor has this characteristics curve? Add description here! Series motor Shunt motor Cumulative compound motor Differential compound motor None 97. What is the purpose of resistor connected with holding coil in 4 point starter? Limit current in NVC Protect the coil from short circuit Protect the motor from overload Protect the armature from short circuit None 98. Why the D.C series motor field winding is wound with thick wire? To regulate field voltage To carry the load current To keep maximum inductance To reduce the armature reaction None 99. Which type of speed control of D.C series motor? Add description here! Field parallel method Field diverter method Field tapping method Armature diverter method None 100. Which type of D.C motor is suitable for shearing machines? Shunt motor Series motor Cumulative compound motor Differential compound motor None 101. Where D.C compound motors are preferred? Constant load requirements Constant speed requirements High starting torque requirements Constant speed under varying load requirements None 102. What is the necessity of starter for D.C motor? Limit the field current Limit the field voltage Control the motor speed Limit the armature current None 103. Which type of instrument is used to test the armature winding? Megger Growler Multimeter Ohmmeter None 104. None 105. Why the holding coil of a 3 point starter is connected in series with shunt field? To limit the load current To run motor at low voltage To hold the handle plunger firmly To protect the motor from high speed None 106. What is the best method to change the DOR of a compound motor without change of its characteristics? Change armature current direction Change shunt field current direction Change series field current direction Change the current in armature and shunt field together None 107. What is the purpose of NVC connected in series with the field in 3 point starter? To improve the torque Reduce the field current To decrease the back emf To prevent increase in speed None 108. Which type of DC motor is used for sudden application of heavy loads? Shunt motor Series motor Differential compound motor Cumulative compound motor None 109. Which speed control method is used in food mixture motors? Voltage control method Field diverter control method Armature diverter method Series field tapping method None 110. Which speed control system provides a smooth variation of speed from zero to above normal? Field control Armature control Field diverter control Ward-Leonard system control None 111. What is the purpose of tapes in winding? Insulate slots Bind the coils Wrap the conductor Insulate exposed conductors None 112. Which type of DC armature winding the front pitch (YF) is greater than back pitch (YB)? Lap winding Wave winding Progressive winding Retrogressive winding None 113. What reduces the cross sectional area of core material for VA rating? Dynamo sheet Low alloy sheet High alloy sheet Normal steel sheet None 114. How to obtain opposite polarity in adjacent poles of a 4 pole DC motor? Varying the number of turns in coil Making series connection of coils Making parallel connection of coils Making current flow in different direction None 115. What is the operation in the rewinding process? Add description here! Cleaning of slots Removing of winding Removing of wedges Cutting of winding wire None 116. Which insulating material used in winding is a highly non -hygroscopic and possess good electrical strength? Empire cloth Triplex paper Millinex paper Leatheroid paper None 117. Which type of armature winding is illustrated? Add description here! Triplex wave winding Duplex wave winding Progressive lap winding Retrogressive lap winding None 118. Calculate the average pitch (YA) for retrogressive wave winding, if No. of armature conductor = 14 No. of slots = 7 No. of poles = 2 4 6 8 14 None 119. Which type of test is illustrated for the armature after rewound? Add description here! Open coil test Shorted coil test Voltage drop test Grounded coil test None 120. Why the newly rewound armature must be preheated before varnishing? Drive out the moisture from it Help for quick drying of varnish Make easy to penetrate varnish inside Maintain uniform spreading of varnishing None 121. How the direction of rotation of a DC compound motor is changed? By changing the direction of armature current By interchanging the supply terminals By changing the direction of both field and armature current By changing the direction of series field current None 122. What is the effect in a D.C shunt motor, if its supply terminals are interchanged? Runs in slow speed Runs in high speed Runs in the same direction Runs in the reverse direction None 123. None 124. What is the speed, if field winding of a DC shunt motor is in open circuit? Stop running | Motor runs normally Runs at slow speed Runs in very high speed None 125. What is the reason for reduction in speed of a D.C shunt motor from no load to full load? | Add description here! Shunt field current increases Shunt field current decreases Armature voltage drop increases Armature voltage drop decreases None 126. Which winding fault is determined by the test Add description here! Open coil fault Short coil fault Grounded coil fault Grounded core fault None 127. None 128. None 129. What is the formula to calculate the slip speed (Nslip) of 3 phase squirrel cage induction motor? None 130. What is the type of control circuit? Add description here! Inching control ON remote control OFF remote control Forward & reverse control None 131. Which formula is used to calculate the total electrical degree in stator of an A.C motor? Total electrical degree = 180° / No. of slots Total electrical degree = 180° x No. of slots Total electrical degree = 180° / No. of poles Total electrical degree = 180° x No. of poles None 132. What is the name of the A.C motor starter? Add description here! DOL starter Auto transformer starter Semi automatic star delta starter Fully automatic star delta starter None 133. What is the formula to find synchronous speed of a A.C 3 phase induction motor? None 134. What is the fuse rate to run a 10 HP three phase induction motor at full load? 10 A 15 A 25 A 30 A None 135. What is the name of the contact marked as X? Star contact Delta contact Auxiliary contact Over load relay contact None 136. What is the type of A.C motor stator winding? Add description here! Single layer basket winding Double layer basket winding Involute coil winding Diamond coil winding None 137. Which formula is used to calculate percentage slip of an AC 3 phase induction motor? None 138. Which operation the control circuit is used? Add description here! Remote control Inching Sequential control Forward and reverse None 139. What is the phase displacement between windings in 3 phase motor? 90° 120° 180° 360° None 140. What is the name of the part marked as X? Add description here! Shaft Brushes Bearings Slip rings None 141. What is the name of AC coil winding? Add description here! Half coil winding Whole coil winding Single layer winding Double layer winding None 142. What is the name of the coil winding? Add description here! Concentric coil winding Distributed coil winding Mesh shaped coil winding Diamond mesh shaped coil winding None 143. Which speed is called as synchronous speed in 3 phase induction motor?Which speed is called as synchronous speed in 3 phase induction motor? No load speed Full load speed Rotating magnetic field speed Relative speed between stator and rotor None 144. What is the name of the starter symbol? Add description here! D.O.L starter Auto transformer starter Automatic star/delta starter Semi automatic star/delta starter None 145. Name the part marked as X of the winding machine? Add description here! Mandrel Wire feed Wire guides Spool carrier None 146. What is the electrical degree of 6 pole stator of motor 360° 720° 1080° 1440° None 147. Calculate the number of coils per phase per pair of poles of 3 phase motor having 2 pole, 24 slots,12 coils? 1 2 3 4 None 148. What is the name of the starter symbol? Add description here! Star delta starter Rheostatic starter Direct on-line starter Autotransformer starter None 149. What is the formula to calculate pitch factor? None 150. What is the synchronous speed of a A.C 3 phase induction motor having 6 poles at a frequency of 50 Hertz? 800 rpm 1000 rpm 1200 rpm 1440 rpm None 151. Calculate the percentage slip in a 3 phase induction motor having 6 poles with a frequency of 50 Hertz rotating with actual speed of 960 rpm? 2% 3% 4% 5% None 152. What is the rotor frequency of a 3 phase squirrel cage induction motor at the time of starting? Equal to supply frequency 3 times less than supply frequency 3 times more than supply frequency √3 times less than supply frequency None 153. How the voltage is received in the rotor of induction motor? Direct connection from stator Due to back emf produced in stator Direct connection to rotor from supply By the transformer action of stator and rotor None 154. Which method is applied to control the speed of 3 phase squirrel cage induction motor from its rotor side? Cascade operation Changing applied voltage Changing applied frequency Changing the number of poles None 155. Why pre heating is necessary for motors before varnishing in rewinding process? To dry the varnish quickly in winding To easy flow of varnish in the winding To increase the insulation resistance value To drive out the moisture in between winding layers None 156. Which loss of 3 phase induction motor is determined by blocked rotor test? Copper loss Friction loss Hysteresis loss Eddy current loss None 157. Which type of test is conducted using internal growler in AC motor winding? Ground test Polarity test Continuity test Short circuit test None 158. Which device is used to test startor winding short and open fault? Tong Tester Internal Growler External Growler Digital multimeter None 159. What is the purpose of using thermal cutout in addition to fuse in A.C motor circuit? Protect from heavy load Protect against high voltage Allow for continuous over loading Protect against dead short circuit None 160. None 161. Which type of motor is used to provide high starting torque at variable speed? Universal motor Permanent capacitor motor 3 Phase slip ring induction motor 3 Phase single squirrel cage induction motor None 162. What is the relation between torque and slip in an A.C induction motor? Slip increases torque decreases Slip increases torque increases Slip decreases torque increases Slip decreases torque decreases None 163. What is effect of A.C induction motor if rotor bar is in open circuit? Vibration of shaft Motor will not start Runs in slow speed Over heating of motor None 164. Which type of wire is used for rewinding of A.C 3 phase motors? Super enamelled copper wire PVC covered copper winding wire Single cotton covered copper wire Double cotton covered copper wire None 165. Which material is used as wedges in winding process? Empire Cotton Bamboo Terylene None 166. Which test in winding is essential before giving supply? Ground test Polarity test Open circuit test Short circuit test | None 167. Why the rotor bars are mounted in a slightly skewed position in 3 phase motor? Generate maximum flux Reduce the stray losses Maintain the rotor speed constant Produce more uniform rotor field and torque None 168. Which loss is determined by no load test of 3 phase induction motor? Iron loss Copper loss Friction loss Windage loss None 169. Which method of speed control two variable speeds only obtained in 3 phase motor? By rotor rheostat control By changing applied frequency By changing the applied voltage By changing the number of stator poles None 170. Why slip ring induction motor is fitted with wound rotor? To reduce the slip To control the speed To reduce the losses To get high starting and running torque None 171. What is the function of timer in automatic star delta starter? Trip at over load Switch ON at pre set time Change from star to delta Switch OFF at pre set time None 172. Which instrument is used to measure insulation resistance of a 3 phase induction motor? Megger Multimeter Shunt type ohmmeter Series type ohmmeter None 173. Which test in winding is illustrated? Add description here! Polarity test Ground test Continuity test Short circuit test None 174. What is the starting current of an A.C 3 phase induction motor? 1 to 2 times of full load current 2 to 3 times of full load current 4 to 5 times of full load current 5 to 6 times of full load current None 175. Which method is used to control the speed of 3 phase induction motor from stator side? By cascade operation By rotor rheostat control By injecting emf in rotor circuit By changing the applied frequency None 176. What is the speed control method of 3 phase induction motor? Add description here! Cascade operation method Rotor rheostat control method Changing applied voltage method Injecting emf in rotor circuit method None 177. What are the two functional circuits incorporated with a three phase motor starter? Open circuit and short circuit Closed circuit and open circuit Short circuit and closed circuit Control circuit and power circuit None 178. Which is the main property of leatheroid paper insulation? Non moisturized material Highly non-hygroscopic Very good for class F insulation Better ageing and dielectric strength None 179. Which type of insulating material is selected for binding the coils and over hangs? Cotton sleeves Empire sleeves Terylene thread Fibre glass tape None 180. Which insulation is used for cuffing in AC winding? Fibre glass tape Leatheroid paper Empire fiber glass tape Fabric based adhesive tape None 181. What refers coil in AC winding? Number of turns connected in series Number of turns connected in parallel Number of turns under two similar poles Number of turns under two dissimilar poles None 182. Which type of AC winding the number of coil/pole/phase is more than one at different pitches? Involute coil winding Diamond coil winding Flat loop over lapped winding Flat loop non-over lapped winding None 183. Calculate the number of coils /phase/ pole for a 3 phase double layer distributed winding for a motor having 36 slots, 36 coils and 4 poles? 3 coils /phase/ pole 6 coils / phase/pole 9 coils / phase/pole 12 coils/ phase/ pole None 184. None 185. What is the type of rewinding process? Add description here! Hand winding Skein winding Former winding Machine winding None 186. Which type of starter is used to start and run the 3 phase slip ring induction motor? Direct on-line starter Rotor rheostat starter Auto transformer starter Manual star-delta starter None 187. What is the function of collar? Add description here! Provides insulation around field Provides insulation for coil tapping Helps tightening material for flange Provides insulation for heat transfer from coil None 188. Which type of winding wire is used to wind submersible pump motors? PVC covered type Terylene thread type Super enamelled type Double cotton covered type None 189. What is the reason of long chord winding is avoided in AC motors? Low efficiency Low starting torque More winding wire required Less heat dissipation None 190. Which type of winding has more space for cooling? Between overhanging coils Between overhanging coil and rotor Between overhanging coils and yoke Between overhanging coil and wedge None 191. Where the panel boards are used? Industrial motor drives Domestic wiring circuits 3 phase domestic wiring Load distribution for AC & DC supply None 192. Determine the torque in newton metres produced by a 7.5 HP squirrel cage motor rotating at 1440 rpm? 21.63 Nm 24.4 Nm 33.05 Nm 36.6 Nm None 193. What is the name of the part marked as 'X' in the DC generator? Armature core Brush Commutator raiser Commutator segment None 194. What is the name of the D.C generator? Differential long shunt compound Differential short shunt compound Cumulative long shunt compound Cumulative short shunt compound None 195. Which rule is used to find the direction of induced emf in a DC generator? Cork screw rule Right hand palm rule Fleming's left-hand rule Fleming's right hand rule None 196. What is the formula to calculate back emf of a D.C motor? Eb = V / Ia Ra Volts Eb = V x Ia Ra Volts Eb = V – Ia Ra Volts Eb = V + Ia Ra Volts None 197. What is the name of the part marked 'X' in the DC generator? Pole tip Pole coil Pole core Pole shoe None 198. What is the name of the D.C generator? Shunt generator Series generator Compound generator Separately excited generator None 199. Which energy is converted into electrical energy by generator? Heat Kinetic Chemical Mechanical None 200. What is the name of the D.C. generator field? Short shunt compound generator Long shunt compound generator Differential compound generator Cumulative compound generator None 201. What is the principle of D.C generator? Cork screw rule Fleming's left-hand rule Fleming's right hand rule Faradays laws of electromagnetic induction None 202. What is the formula for dynamically induced emf? BLV volts BL sinθ volts BLV sinθ volts BLV cosθ volts None 203. Which rule is used to find direction of the magnetic field? Cork screw rule Right hand palm rule Fleming’s left hand rule Fleming’s right hand rule None 204. What is the name of the part of the DC generator? Stator Yoke (or) frame Pole core Pole shoes None 205. How many parallel paths in duplex lap winding of a 4 pole Dc Generator? 4 6 8 12 None 206. Name the part of the DC generator? Side end plates Pole shoe lamination Commutator segment Armature core lamination None 207. How are interpoles connected in a DC generator? series with armature parallel with armature In series with shunt field In parallel with shunt field None 208. What is the necessity of residual magnetism in a self excited DC generator? Build up the voltage Reduce the field current Reduce armature current Maintain constant output voltage None 209. Which are the two points that the brush contact resistance measured in D.C machines? Resistance between the opposite brushes Resistance between brush and commutator raiser Resistance between brush and commutator Resistance between brush and armature conductors None 210. Which voltage drop is indicated in the portion marked as x? Full load voltage drop Armature voltage drop Armature reaction drop Shunt field voltage drop None 211. What is the name of the compound generator, if the shunt field is connected in parallel with the armature? Long shunt compound Cumulative compound Differential compound Short shunt compound None 212. Why is the armature core of a DC generator laminated? Reduce the copper loss Reduce the friction loss Reduce the hysteresis loss Reduce the eddy current loss None 213. Why armature resistance of a D.C generator is very low? Reduce armature current Reduce armature voltage drop Run armature with less weight Reduce the temperature of armature None 214. Why does the D.C generator run in clockwise direction only? Protect brushes from damage Protect the residual magnetism Avoid short circuit in armature Avoid overloading of generator None 215. Why compensating winding is provided in large DC generators? Connect more loads Reduce commutation effect Neutralize armature reaction effect Increase the efficiency of generator None 216. What is the reason for the DC generator failing to build up voltage? Loose brush contact Armature resistance is more Field resistance is above critical resistance Prime mover is running at above rated speed None 217. What is the name of a generator, if its field is connected in parallel with armature? Shunt generator Series generator Compound generator Self excited generator None 218. What is the purpose of pole shoe in a DC generator? Reduce the air gap Increase the field strength Minimize the magnetic losses Spread out flux uniformly in the air gap None 219. What is the function of split rings in a DC generator? Maintain constant voltage Collects the current unidirectionally Reduces the voltage drop at brushes Increases the terminal voltage than rated None 220. Which material is used to make a brush in a generator? Steel and graphite Carbon and graphite Cast iron and graphite Aluminium and graphite None 221. Why DC generators are losing their residual magnetism? Heavy short circuit in load Running without load continuously Continuous running without break Change of direction of rotation very often None 222. How does the magnetic circuit complete through the yoke and poles in the generator? Field coils Armature core Laminated pole core Winding conductors in armature None 223. Why does the terminal voltage decrease if load increases in the DC shunt generator? Because of armature reaction effect Due to increased in armature resistance Because of brush voltage drop decreases Due to increased in shunt field inductance None 224. Which type of DC generator is used for long distance distribution lines? Shunt generator Series generator Differential compound generator Cumulative compound generator None 225. Which method is used to improve the insulation resistance in a DC generator? Replacing the brushes frequently Heating the machine by running periodically Cleaning the commutator segments regularly Blowing hot air in to the machine during maintenance None 226. Which type of D.C Generator works in absence of residual magnetism? Shunt generator Series generator Compound generator Separately excited generator None 227. Which type of D.C generator is used for arc welding? Shunt generator Series generator Differential compound generator Cumulative compound generator None 228. What is the property of wave winding in D.C generator? Low current low voltage High current low voltage Low current high voltage High current high voltage None 229. What is the purpose of resistance wire used in the commutator connection in D.C generator? Maintain constant voltage Nullifying statically induced emf Increasing statically induced emf Smooth reversal of current direction None 230. Why solid pole shoes are used in D.C generators? To increase the residual magnetism To decrease the residual magnetism To reduce the reluctance of magnetic path None 231. Which metal is used to make a large capacity D.C generator yoke? Cast iron soft iron Aluminium Rolled Steel None 232. What is the function of split rings in a D.C generator? Supplies output continuously Makes output in the uni direction Makes output in the opposite direction Collects the output from alternate conductors None 233. Which type of voltage is induced dynamically in a D.C generator? Pulsating voltage Oscillating voltage Alternating voltage Direct current voltage None 234. What is the purpose of a slot marked as 'X'? To fix the key way To make air circulation For lubrication purpose For easy removal from shaft None 235. What is the purpose of field coils in a D.C. generator? increase the flux in air gap decrease the magnetizing current magnetize the poles to produce coil flux increase the reluctance of magnetic path None 236. Which metal is used to make pole core of large DC generator machines? Soft iron Cast iron Cast steel Stainless steel None 237. Why the pole core stampings are laminated in DC generator? Reduce the friction loss Reduce the windage loss Reduce the hysteresis loss Reduce the eddy current loss None 238. Which type of DC generator is used for the electroplating process? shunt generator Series generator Differential compound generator Cumulative compound generator None 239. What is the purpose of compensating winding in DC generator? Minimizes rough commutation Maintain constant output voltage Neutralizes the demagnetizing effect Decreases the excitation current of field coils None 240. What is the effect if the shunt field resistance is above critical resistance value in a D.C generator? Output voltage is pulsating Output voltage is above normal Generator fails to build up voltage Generator builds up voltage normally None 241. What is the effect of armature reaction in DC generator? Output voltage increases Output voltage decreases Output voltage is pulsating Output voltage will become zero None 242. Calculate the emf generated in a 4 pole DC generator with simplex wave wound armature has 1020 conductors and driven at a speed of 1500 rpm, the flux/pole is 0.007 Weber's? 178V 243V 357V 428V None 243. Which instrument is used to measure armature winding resistance? Megger Multimeter Series type Ohmmeter Kelvin bridge None 244. What is the name of the speed control method of a DC motor? Field diverter method Field tapping method Voltage control method Armature diverter method None 245. Which winding wire is used for DC field coil? Super enameled copper wire Single silk covered copper wire Double silk covered copper wire PVC covered copper winding wire None 246. How many parallel paths in duplex lap winding in the armature of 4 pole D.C Motor? 2 4 6 8 None 247. Which rule determines the direction of rotation of the armature in a DC motor? Right hand grip rule Right hand palm rule Fleming's left hand rule Fleming's right hand rule None 248. What is the name of D.C motor? D.C shunt motor D.C series motor D.C differential compound motor DC cumulative compound motor None 249. Which rule determines the direction of current in a DC motor? Right hand grip rule Right hand palm rule Fleming's left hand rule Fleming's right hand rule None 250. Name the type of DC motor. Shunt motor Series motor Long shunt compound motor Short shunt compound motor None 251. What is the name of the equipment? Megger Earth resistance tester Internal growler External growler None 252. What is the name of winding, if coil pitch is less than pole pitch? full pitch winding Half pitch winding Long corded winding Short corded winding None 253. What is the purpose of series resistor connected with holding coil in a D.C four point starter? Limit the current in holding coil Increase the current in holding coil Increase the voltage in holding coil Decrease the voltage in holding coil None 254. Which speed control method of D.C series motor is used for electric trains? Field diverter method Field tapping method Armature diverter method Supply voltage control method None 255. Why shunt field coil is connected in series with holding coil in D.C three point starter? Increase the holding coil current Decrease the holding coil current Protect the shunt field from over current Protect the motor in case of open in shunt field None 256. Why the direction of rotation is changed only by changing the armature current direction in a D.C compound motor? Maintain rated speed Maintain motor characteristics Avoid armature reaction effect | Prevent motor from over loading None 257. Which speed control methods offer below normal speed in Dc shunt motor? Field control method Voltage control method Armature control method Ward Leonard system of speed control None 258. Which insulating material belongs to class 'B' insulation? Cotton Bamboo Fibreglass Leatheroid paper None 259. What is the temperature value of class 'F' insulation? 90°C 105°C 120°C 155°C None 260. Which type of D.C motor is used for constant speed drives? DC series motor DC shunt motor Differential long shunt compound motor Differential short shunt compound motor None 261. Which type of DC motor is used in elevators? Dc series motor Dc shunt motor Dc differential compound motor DC cumulative compound motor None 262. Which method of speed control gives below the rated speed in DC series motor? Field diverter method Tapped field method Voltage control method Armature diverter method None 263. Why carbon composition brush requires in the armature circuit to operate the D.C motor? Increases the starting torque Protects from armature reaction Protects armature from over loading Reduces the spark in the commutator segment None 264. Why series motors produce high torque and speed initially without load? Absence of back emf Load current flows through field winding Armature current and field current are same Series field winding wound with thick wire None 265. Why the series field is short circuited at the time of starting in differential compound motor? To reduce the starting current To increase the speed of motor To decrease the speed of motor To maintain proper direction of rotation None 266. Which material is used for starting resistance of DC starters? Eureka Nichrome Manganin Constantine None 267. Which type of armature winding is illustrated? Duplex lap winding Triplex lap winding Simplex lap winding Quadruplex lap winding None 268. Which growler test for armature is illustrated? Open coil test | Grounded coil test Shorted coil test Shorted commutator test None 269. Which speed control method is applied to obtain both below normal and above normal speed in a DC motor? Field control method Armature control method Tapped field speed control Ward Leonard speed control None 270. Why are commutators sparking heavily? Incorrect brush position Incorrect field connection Incorrect direction of rotation Incorrect armature connection None 271. Which motor has this characteristic curve? Series motor Shunt motor Cumulative compound motor Differential compound motor None 272. Which type of speed control of D.C series motor? Field parallel method Field diverter method Field tapping method Armature diverter method None 273. Which type of D.C motor is suitable for shearing machines? Shunt motor Series motor Cumulative compound motor Differential compound motor None 274. What is the necessity of a starter for D.C motor? Limit the field current Limit the field voltage Control the motor speed | Limit the armature current None 275. Which type of instrument is used to test the armature winding? Megger Growler Multimeter Ohmmeter None 276. Why the holding coil of a 3 point starter is connected in series with shunt field? To limit the load current To run motor at low voltage To hold the handle plunger firmly To protect the motor from high speed None 277. What is the purpose of NVC connected in series with the field in 3 point starter? To improve the torque Reduce the field current To decrease the back emf To Prevent increase in speed None 278. Which type of DC motor is used for sudden application of heavy loads? Shunt motor Series motor Differential compound motor Cumulative compound motor None 279. Which speed control system provides a smooth variation of speed from zero to above normal? Field control Armature control Field diverter control Ward-Leonard system control None 280. What is the purpose of tapes in winding? Insulate slots Bind the coils Wrap the conductor Insulate exposed conductors None 281. Which type of DC armature winding the front pitch (Yf) is greater than back pitch (YB)? Lap winding Wave winding Progressive winding Retrogressive winding None 282. How to obtain opposite polarity in adjacent poles of a 4 pole DC motor? Varying the number of turns in coil Making series connection of coils Making parallel connection of coils Making current flow in different direction None 283. What is the operation in the rewinding process? Cleaning of slots Removing of winding Removing of wedges Cutting of winding wire None 284. Which type of armature winding is illustrated? Triplex wave winding Duplex wave winding Progressive lap winding Retrogressive lap winding None 285. How the direction of rotation of a DC compound motor is changed? By changing the direction of armature current By interchanging the supply terminals By changing the direction of both field and armature current By changing the direction of series field current None 286. What is the purpose of tapes in winding? Insulate slots Bind the coils Wrap the conductor Insulate exposed conductors None 287. Which winding fault is determined by the test? Open coil fault Short coil fault Grounded coil fault Grounded core fault None 288. Which DC compound motor is operated at constant speed under varying load? Differential long shunt Cumulative long shunt Differential short shunt None 289. How No volt coil is connected in a three point starter with DC shunt motor? Directly connected to supply Connected in series with armature Differential short shunt | Connected in parallel with armature Connected in series with shunt field None 290. What is the purpose of resistor connected with holding coil in 4 point starter? Limit current in NVC Protect the coil from short circuit Protect the motor from overload Protect the armature from short circuit None 291. What is the type of control circuit? Inching control ON remote control OFF remote control Forward & reverse control None 292. What is the name of the A.C motor starter? DOL starter Auto transformer starter Semi automatic star delta starter Fully automatic star delta starter None 293. Which formula is used to calculate the total electrical degree in stator of an A.C motor? Total electrical degree = 180°/No. of slots Total electrical degree = 180° x No. of slots Total electrical degree = 180°/No. of poles Total electrical degree = 180° x No. of poles None 294. What is the fuse rate to run a 10 HP three phase induction motor at full load? 10A 15A 25A 30A None 295. What is the name of the contact marked as x? star contact Delta contact Auxiliary contact Over load relay contact None 296. What is the type of A.C motor stator winding? Single layer basket winding Double layer basket winding In-volute coil winding Diamond coil winding None 297. Which operation the control circuit is used? Remote control Inching Sequential control Forward and reverse None 298. What is the synchronous speed of a A.C. 3 phase induction motor having 6 poles at a frequency of 50 Hertz? 800 rpm 1000 rpm 1200 rpm 1440 rpm None 299. Calculate the percentage slip in a 3 phase induction motor having 6 poles with a frequency of 50 Hertz rotating with actual speed of 960 rpm? 2% 3% 4% 5% None 300. What is the name of the part marked as 'X' in the DC generator? Armature core Brush Commutator raiser Commutator segment None 301. What is the name of the D.C generator? Differential long shunt compound Differential short shunt compound Cumulative long shunt compound Cumulative short shunt compound None 302. Which rule is used to find the direction of induced emf in a DC generator? Cork screw rule Right hand palm rule Fleming's left-hand rule Fleming's right hand rule None 303. What is the formula to calculate back emf of a D.C motor? Pole tip Pole coil Pole core Pole shoe None 304. What is the name of the D.C generator? Shunt generator Series generator Compound generator Separately excited generator None 305. Which energy is converted into electrical energy by generator? Heat Kinetic Chemical Mechanical None 306. What is the name of the D.C. generator field? Short shunt compound generator Long shunt compound generator Differential compound generator farach Cumulative compound generator None 307. What is the principle of D.C generator? Cork screw rule Fleming's left-hand rule Fleming's right hand rule Faradays laws of electromagnetic induction None 308. What is the formula for dynamically induced emf? BLV volts BL sinθ volts BLV sinθ volts BLV cosθ volts None 309. Which rule is used to find direction of the magnetic field? Cork screw rule Right hand palm rule Fleming’s left hand rule Fleming’s right hand rule None 310. What is the name of the part of the DC generator? Stator Yoke (or) frame Pole core Pole shoes None 311. How many parallel paths in duplex lap winding of a 4 pole Dc Generator? 4 6 8 12 None 312. Name the part of the DC generator? Side end plates Pole shoe lamination Commutator segment Armature core lamination None 313. How are interpoles connected in a DC generator? In series with armature In parallel with armature In series with shunt field In parallel with shunt field None 314. What is the necessity of residual magnetism in a self excited DC generator? Build up the voltage Reduce the field current Reduce armature current Maintain constant output voltage None 315. Which are the two points that the brush contact resistance measured in D.C machines? Resistance between the opposite brushes Resistance between brush and commutator raiser Resistance between brush and commutator Resistance between brush and armature conductors None 316. Which voltage drop is indicated in the portion marked as x? Full load voltage drop Armature voltage drop Armature reaction drop Shunt field voltage drop None 317. What is the name of the compound generator, if the shunt field is connected in parallel with the armature? Long shunt compound Cumulative compound Differential compound Short shunt compound None 318. Why is the armature core of a DC generator laminated? Reduce the copper loss Reduce the friction loss Reduce the hysteresis loss Reduce the eddy current loss None 319. Why armature resistance of a D.C generator is very low? Reduce armature current Reduce armature voltage drop Run armature with less weight Reduce the temperature of armature None 320. Why does the D.C generator run in clockwise direction only? Protect brushes from damage Protect the residual magnetism Avoid short circuit in armature Avoid overloading of generator None 321. Why compensating winding is provided in large DC generators? Connect more loads Reduce commutation effect Neutralize armature reaction effect Increase the efficiency of generator None 322. What is the reason for the DC generator failing to build up voltage? Loose brush contact Armature resistance is more Field resistance is above critical resistance Prime mover is running at above rated speed None 323. What is the name of a generator, if its field is connected in parallel with armature? Shunt generator Series generator Compound generator Self excited generator None 324. What is the purpose of pole shoe in a DC generator? Reduce the air gap Increase the field strength Minimize the magnetic losses Spread out flux uniformly in the air gap None 325. What is the function of split rings in a DC generator? Maintain constant voltage Collects the current unidirectionally Reduces the voltage drop at brushes Increases the terminal voltage than rated None 326. Which material is used to make a brush in a generator? Steel and graphite Carbon and graphite Cast iron and graphite Aluminium and graphite None 327. Why DC generators are losing their residual magnetism? Heavy short circuit in load Running without load continuously Continuous running without break Change of direction of rotation very often None 328. How does the magnetic circuit complete through the yoke and poles in the generator? Field coils Armature core Laminated pole core Winding conductors in armature None 329. Why does the terminal voltage decrease if load increases in the DC shunt generator? Because of armature reaction effect Due to increased in armature resistance Because of brush voltage drop decreases Due to increased in shunt field inductance None 330. Which type of DC generator is used for long distance distribution lines? Shunt generator Series generator Differential compound generator Cumulative compound generator None 331. Which method is used to improve the insulation resistance in a DC generator? Replacing the brushes frequently Heating the machine by running periodically Cleaning the commutator segments regularly Blowing hot air in to the machine during maintenance None 332. Which type of D.C Generator works in absence of residual magnetism? Shunt generator Series generator Compound generator Separately excited generator None 333. Which type of D.C generator is used for arc welding? Shunt generator Series generator Differential compound generator Cumulative compound generator None 334. What is the property of wave winding in D.C generator? Low current low voltage High current low voltage Low current high voltage High current high voltage None 335. What is the purpose of resistance wire used in the commutator connection in D.C generator? Maintain constant voltage Nullifying statically induced emf Increasing statically induced emf Smooth reversal of current direction None 336. Why solid pole shoes are used in D.C generators? To reduce the copper loss To increase the residual magnetism To decrease the residual magnetism To reduce the reluctance of magnetic path None 337. Which metal is used to make a large capacity D.C generator yoke? Cast iron soft iron Aluminium Rolled Steel None 338. What is the function of split rings in a D.C generator? Supplies output continuously Makes output in the uni direction Makes output in the opposite direction Collects the output from alternate conductors None 339. Which type of voltage is induced dynamically in a D.C generator? Pulsating voltage Oscillating voltage Alternating voltage Direct current voltage None 340. What is the purpose of field coils in a D.C. generator? To increase the flux in air gap To decrease the magnetizing current To magnetize the poles to produce coil flux To increase the reluctance of magnetic path None 341. Which metal is used to make pole core of large DC generator machines? Soft iron Cast iron Cast steel Stainless steel None 342. Why the pole core stampings are laminated in DC generator? Reduce the friction loss Reduce the windage loss Reduce the hysteresis loss Reduce the eddy current loss None 343. Which type of DC generator is used for the electroplating process? shunt generator Series generator Differential compound generator None 344. What is the purpose of compensating winding in DC generator? Minimizes rough commutation Maintain constant output voltage Neutralizes the demagnetizing effect Neutralizes the demagnetizing effect None 345. What is the effect if the shunt field resistance is above critical resistance value in a D.C generator? Output voltage is pulsating Output voltage is above normal Generator fails to build up voltage Generator builds up voltage normally None 346. What is the effect of armature reaction in DC generator? Output voltage increases Output voltage decreases Output voltage is pulsating Output voltage will become zero None 347. Calculate the emf generated in a 4 pole DC generator with simplex wave wound armature has 1020 conductors and driven at a speed of 1500 rpm, the flux/pole is 0.007 Weber's? 178V 243V 357V 428V None 348. Which instrument is used to measure armature winding resistance? Megger Multimeter Series type Ohmmeter Kelvin bridge None 349. Which instrument is used to test armature winding for short and open circuits? Tong Tester Internal Growler External Growler Digital multimeter None 350. What is the name of the speed control method of a DC motor? Field diverter method Field tapping method Voltage control method Armature diverter method None 351. Which winding wire is used for DC field coil? Super enameled copper wire Single silk covered copper wire Double silk covered copper wire PVC covered copper winding wire None 352. Which formula is used to calculate the speed of DC motor? None 353. How many parallel paths in duplex lap winding in the armature of 4 pole D.C Motor? 2 4 6 8 None 354. Which rule determines the direction of rotation of the armature in a DC motor? Right hand grip rule Right hand palm rule Fleming's left hand rule Fleming's right hand rule None 355. What is the name of D.C motor? D.C shunt motor D.C series motor D.C differential compound motor DC cumulative compound motor None 356. Which rule determines the direction of current in a DC motor? Right hand grip rule Right hand palm rule Fleming's left hand rule Fleming's right hand rule None 357. Name the type of DC motor. Shunt motor Series motor Long shunt compound motor Short shunt compound motor None 358. What is the name of the equipment? Megger Earth resistance tester Internal growler External growler None 359. What is the name of winding, if coil pitch is less than pole pitch? Full pitch winding Half pitch winding Long corded winding Short corded winding None 360. What is the purpose of series resistor connected with holding coil in a D.C four point starter? Limit the current in holding coil Increase the current in holding coil Increase the voltage in holding coil Decrease the voltage in holding coil None 361. Which speed control method of D.C series motor is used for electric trains? Field diverter method Field tapping method Armature diverter method Supply voltage control method None 362. Why shunt field coil is connected in series with holding coil in D.C three point starter? Increase the holding coil current Decrease the holding coil current Protect the shunt field from over current Protect the motor in case of open in shunt field None 363. Why the direction of rotation is changed only by changing the armature current direction in a D.C compound motor? Maintain rated speed Maintain motor characteristics Avoid armature reaction effect Prevent motor from over loading None 364. Which speed control methods offer below normal speed in Dc shunt motor? Field control method Voltage control method Armature control method Ward Leonard system of speed control None 365. Which insulating material belongs to class 'B' insulation? Cotton Bamboo Fibreglass Leatheroid paper None 366. What is the temperature value of class 'F' insulation? 90°C 105°C 120°C 155°C None 367. Which type of D.C motor is used for constant speed drives? DC series motor DC shunt motor Differential long shunt compound motor Differential short shunt compound motor None 368. Which type of DC motor is used in elevators? Dc series motor Dc shunt motor Dc differential compound motor DC cumulative compound motor None 369. Which method of speed control gives below the rated speed in DC series motor? Field diverter method Tapped field method Voltage control method Armature diverter method None 370. Why carbon composition brush requires in the armature circuit to operate the D.C motor? Increases the starting torque Protects from armature reaction Protects armature from over loading Reduces the spark in the commutator segment None 371. Why series motors produce high torque and speed initially without load? Absence of back emf Load current flows through field winding Armature current and field current are same Series field winding wound with thick wire None 372. Why the series field is short circuited at the time of starting in differential compound motor? To reduce the starting current To increase the speed of motor To decrease the speed of motor To maintain proper direction of rotation None 373. Which material is used for starting resistance of DC starters? Eureka Nichrome Manganin Constantine None 374. Which type of armature winding is illustrated? Duplex lap winding Triplex lap winding Simplex lap winding Quadruplex lap winding None 375. Which growler test for armature is illustrated? Open coil test Grounded coil test Shorted coil test Shorted commutator test None 376. Which speed control method is applied to obtain both below normal and above normal speed in a DC motor? Field control method Armature control method Tapped field speed control Ward Leonard speed control None 377. Why are commutators sparking heavily? Incorrect brush position Incorrect field connection Incorrect direction of rotation Incorrect armature connection None 378. Which motor has this characteristic curve? Series motor Shunt motor Cumulative compound motor Differential compound motor None 379. Which type of speed control of D.C series motor? Field parallel method Field diverter method Field tapping method Armature diverter method None 380. Which type of D.C motor is suitable for shearing machines? Shunt motor Series motor Cumulative compound motor Differential compound motor None 381. What is the necessity of a starter for D.C motor? Limit the field current Limit the field voltage Control the motor speed Limit the armature current None 382. Which type of instrument is used to test the armature winding? Megger Growler Multimeter Ohmmeter None 383. Why the holding coil of a 3 point starter is connected in series with shunt field? To limit the load current To run motor at low voltage To hold the handle plunger firmly To protect the motor from high speed None 384. What is the purpose of NVC connected in series with the field in 3 point starter? To improve the torque Reduce the field current To decrease the back emf To Prevent increase in speed None 385. Which type of DC motor is used for sudden application of heavy loads? Shunt motor Series motor Differential compound motor Cumulative compound motor None 386. Which speed control system provides a smooth variation of speed from zero to above normal? Field control Armature control Field diverter control Ward-Leonard system control None 387. What is the purpose of tapes in winding? Insulate slots Bind the coils Wrap the conductor Insulate exposed conductors None 388. Which type of DC armature winding the front pitch (Yf) is greater than back pitch (YB)? Lap winding Wave winding Progressive winding Retrogressive winding None 389. How to obtain opposite polarity in adjacent poles of a 4 pole DC motor? Varying the number of turns in coil Making series connection of coils Making parallel connection of coils Making current flow in different direction None 390. What is the operation in the rewinding process? Cleaning of slots Removing of winding Removing of wedges Cutting of winding wire None 391. Which type of armature winding is illustrated? Triplex wave winding Duplex wave winding Progressive lap winding Retrogressive lap winding None 392. How the direction of rotation of a DC compound motor is changed? By changing the direction of armature current By interchanging the supply terminals By changing the direction of both field and armature current By changing the direction of series field current None 393. What is the purpose of tapes in winding? Insulate slots Bind the coils Wrap the conductor Insulate exposed conductors None 394. Which winding fault is determined by the test? Open coil fault Short coil fault Grounded coil fault Grounded core fault None 395. Which DC compound motor is operated at constant speed under varying load? Differential long shunt Cumulative long shunt Differential short shunt None 396. How No volt coil is connected in a three point starter with DC shunt motor? Directly connected to supply Connected in series with armature Differential short shunt | Connected in parallel with armature Connected in series with shunt field None 397. What is the purpose of resistor connected with holding coil in 4 point starter? Limit current in NVC Protect the coil from short circuit Protect the motor from overload Protect the armature from short circuit None 398. What is the type of control circuit? Inching control ON remote control OFF remote control Forward & reverse control None 399. What is the name of the A.C motor starter? DOL starter Auto transformer starter Semi automatic star delta starter Fully automatic star delta starter None 400. Which formula is used to calculate the total electrical degree in stator of an A.C motor? Total electrical degree = 180°/No. of slots Total electrical degree = 180° x No. of slots Total electrical degree = 180°/No. of poles Total electrical degree = 180° x No. of poles None 401. What is the fuse rate to run a 10 HP three phase induction motor at full load? 10A 15A 25A 30A None 402. What is the name of the contact marked as x? star contact Delta contact Auxiliary contact Over load relay contact None 403. What is the type of A.C motor stator winding? Single layer basket winding Double layer basket winding In-volute coil winding Diamond coil winding None 404. Which operation the control circuit is used? Remote control Inching Sequential control Forward and reverse None 405. What is the synchronous speed of a A.C. 3 phase induction motor having 6 poles at a frequency of 50 Hertz? 800 rpm 1000 rpm 1200 rpm 1440 rpm None 406. Calculate the percentage slip in a 3 phase induction motor having 6 poles with a frequency of 50 Hertz rotating with actual speed of 960 rpm? 2% 3% 4% 5% None 407. What is the rotor frequency of a 3 phase squirrel cage induction motor at the time of starting? Equal to supply frequency 3 times less than supply frequency 3 times more than supply frequency None 408. Which type of test is conducted using internal growler in AC motor winding? Ground test Polarity test Continuity test Short circuit test None 409. Which method is applied to control the speed of 3 phase squirrel cage induction motor from its rotor side? Cascade operation Changing applied voltage Changing applied frequency Changing the number of poles None 410. Which device is used to test starter winding short and open fault? Tong Tester Internal Growler External Growler Digital multimeter None 411. Which loss of 3 phase induction motor is determined by blocked rotor test? Copper loss Friction loss Hysteresis loss Eddy current loss None 412. What is the purpose of using thermal cutout in addition to fuse in AC motor circuit? Protect from heavy load Protect against high voltage Allow for continuous over loading Protect against dead short circuit None 413. Why preheating is necessary for motors before varnishing in rewinding process? To dry the varnish quickly in winding To easy flow of varnish in the winding To increase the insulation resistance value To drive out the moisture in between winding layers None 414. Which type of motor is used to provide high starting torque at variable speed? Universal motor Permanent capacitor motor 3 Phase slip ring induction motor 3 Phase single squirrel cage induction motor None 415. Which material is used as wedges in winding process? Empire Cotton Bamboo Terylene None 416. What is the relation between torque and slip in an AC induction motor? slip increases torque decreases slip increases torque increases slip decreases torque increases slip decreases torque decreases None 417. which test in winding is essential before giving supply? Ground test Polarity test Open circuit test Short circuit test None 418. What is effect of A.C induction motor if rotor bar is in open circuit? Vibration of shaft Motor will not start Runs in slow speed Over heating of motor None 419. Why the rotor bars are mounted in a slightly skewed position in 3 phase motor? Generate maximum flux Reduce the stray losses Maintain the rotor speed constant Produce more uniform rotor field and torque None 420. Which type of wire is used for rewinding of A.C 3 phase motors? Super enamelled copper wire Pvc covered copper winding wire Single cotton covered copper WIRE Double cotton covered copper wire None 421. which loss is determined by no load test of 3 phase induction motor? Iron loss Copper loss Friction loss Windage loss None 422. Why slip ring induction motor is fitted with wound rotor? To reduce the slip To control the speed Toreduce the losses To get high starting and running torque None 423. which test in winding is illustrated? Polarity test Ground test Continuity test Short circuit test None 424. What is the function of timer in automatic star delta starter? Trip at over load Switch ON at preset time Change from star to delta Switch OFF at pre set time None 425. What is the starting current of an A.C 3 phase induction motor? 1 to 2 times of full load current 2 to 3 times of full load current 4 to 5 times of full load current 5 to 6 times of full load current None 426. Which instrument is used to measure insulation resistance of a 3 phase induction motor? Megger Multimeter Shunt type ohmmeter Series type ohmmeter None 427. Which insulation is used for cuffing in AC winding? Fibre glass tape Leatheroid paper Empire fibre glass tape Fabric based adhesive tape None 428. What are the two functional circuits incorporated with a three phase motor starter? open circuit and short circuit Closed circuit and open circuit Short circuit and closed circuit Control circuit and power circuit None 429. What refers coil in AC winding? Number of turns connected in series Number of turns connected in parallel Number of turns under two similar poles Number of turns under two dissimilar poles None 430. Which is the main property of leatheroid paper insulation? Non moisturized material Highly non-hygroscopic Very good for class F insulation Better ageing and dielectric strength None 431. Calculate the number of coils/phase/pole for a 3 phase double layer distributed winding for a motor having 36 slots, 36 coils and 4 poles? 3 coils/phase/pole 6 coils/phase/pole 9 coils/phase/pole 12 coils/phase/pole None 432. What is the type of rewinding process? Hand winding Skein winding Former winding Machine winding None 433. Which type of winding wire is used to wind submersible pump motors? Pvc covered type Terylene thread type Super enamelled type Double cotton covered type None 434. Which type of starter is used to start and run the 3 phase slip ring induction motor? Direct on-line starter Rotor rheostat starter Auto transformer starter Manual star-delta starter None 435. What is the reason of long chord winding is avoided in Ac motors? Low efficiency Low starting torque More winding wire required Less heat dissipation None 436. What is the formula to calculate the slip speed (Nslip) of 3 phase squirrel cage induction motor? Nslip = Ns – Nr Nslip = Nr – Ns Nslip = Ns – Nr / Nr Nslip = Ns – Nr / Ns None 437. What is the function of collar? Provides insulation around field Provides insulation for coil tapping Helps tightening material for flange Provides insulation for heat transfer from coil None 438. Which type of winding has more space for cooling? Between overhanging coils Between overhanging coil and rotor Between overhanging coils and yoke Between overhanging coil and wedge None 439. Where the panel boards are used? Industrial motor drives Domestic wiring circuits 3 phase domestic wiring Load distribution for AC & DC supply None 440. Determine the torque in newton metres produced by a 7.5 HP squirrel cage motor rotating at 1440 rpm? 21.63 Nm 24.4 Nm 33.05Nm 36.6 Nm None 441. Which type of handle design of rotary switch is illustrated? Knob Lever coin slot Key operation None 442. What is the purpose of using rotor resistance starter to start 3 phase slip ring induction motor? Reduce rotor voltage Reduce rotor current Increase the torque Reduce the power loss None 443. Which method of speed control is only applicable for 3 phase slip ring induction motor? Cascade operation method Rotor rheostat speed control Changing the applied frequency method Changing the number of stator poles method None 444. What is the name of the winding? Skew winding Skein winding Involute coil winding Diamond coil winding None 445. What is the name of 3 phase motor winding, if the coil pitch is less than pole pitch? Full pitch winding Whole coil winding Long chorded winding Short chorded winding None 446. Which is the demerit of 3 phase concentric winding? More space is required A stepped former is required More difficult to shape the coils uniformly It is not easy to make the end connection None 447. Which type of AC motor winding having the number of coil/pole/phase is more than one arranged in different slots? Basket winding Concentric winding Distributed winding Concentrated winding None 448. What is the name of the part marked as X? Shaft Brushes Bearings Slip rings None 449. What is the name of AC coil winding? Half coil winding Whole coil winding Single layer winding Double layer winding None 450. What is the name of the coil winding? Concentric coil winding Distributed coil winding Mesh shaped coil winding Diamond mesh shaped coil winding None 451. Which speed is called as synchronous speed in 3 phase induction motor? No load speed Full load speed Rotating magnetic field speed Relative speed between stator and rotor None 452. What is the name of the starter symbol? D.O.L starter Auto transformer starter Automatic star/delta starter Semi automatic star/delta starter None 453. Name the part marked as X of the winding machine? Mandrel Wire feed Wire guides Spool carrier None 454. What is the electrical degree of 6 pole stator of motor? 360° 720° 1080° 1440° None 455. What is the effect of motor, if the rotor windings in slipring induction motor is open circuited at starting? will not run Runs at slow speed Runs at very high speed Runs but not able to pull load None 456. What happens to a 3 phase induction motor if one phase fails during running? Motor runs normally Motor stop instantaneously Motor runs slowly, finally it burns Motor runs with irregular speed None 457. What is the effect on 3 phase induction motor if one phase is cut-off during running with load? Motor stops at once Motor will run normally Motor runs with humming noise with slow speed Motor will run slow speed but winding will be burnt out shortly None 458. What is the defect, if starter with single phasing preventer does not switch ON? Improper phase sequence Fluctuations in line voltage Loose contact in supply lines Wrong terminal connections at motor None 459. What is the defect in AC 3 phase induction motor runs at low speed if loaded? Wrong motor connection Wrong starter connection open circuit in rotor winding Partially shorted stator winding None 460. Which fault condition thermal overload relay protects A.C induction motor? Short circuit open circuit Over current Under voltage None 461. Which is the cause for the 3 phase motor starter with single phase presenter trips frequently? Incorrect fuse ratings Unbalanced line voltage Incorrect settings of OLR Improper phase sequence None 462. What is the effect of open circuit in rotor of an induction motor? Motor does not start Over heating in motor Excess vibration of shaft Motor runs with very low speed None 463. What is the reason for frequent blowing of fuse after motor running some time? Improper earthing over loading of motor Heavy voltage fluctuation Poor insulation in winding None 464. What indication denotes the shorted coil defect in 3 phase motor stater winding while testing with internal growler by keeping hacksaw blade? Hacksaw blade gets over heated Hacksaw Rapid vibration of hacksaw blade Hacksaw blade repels against the slots Attracted by the winding turns on the slot None 465. What happens to a 3 phase induction motor, if one phase fails during starting? Motor runs and stop immediately Motor runs in slow speed continuously Motor runs and draws more current | Motor continues to run with irregular speed None 466. vWhich type of testing of winding is illustrated? Polarity test Resistance test Short circuit test voltage drop test None 467. What is the working principle of single phase induction motor? Lenz's law Joule's law Faraday's laws of electrolysis Faraday's laws of electromagnetic induction None 468. What is the name of single phase motor? Permanent capacitor motor Universal motor Capacitor start induction run motor Capacitor start capacitor run motor None 469. What is the working principle of split phase motor? Lenz's law Joule's law Faraday's laws of electrolysis Faraday's laws of electromagnetic induction None 470. Which type of single phase motor is illustrated? Permanent capacitor motor Universal motor Capacitor start induction run motor Capacitor start capacitor run motor None 471. Which type of A.C single phase motor is classified under commutator motor type? Stepper motor Repulsion motor Shaded pole motor Permanent capacitor motor None 472. Which method is adopted to start the single phase induction motor? Split phase method Varying supply voltage method Reversal of input supply terminals Reversal of running coil connection None 473. What is the type of A.C single phase motor? Permanent capacitor motor Universal motor Capacitor start induction run motor Capacitor start capacitor run motor None 474. What is the purpose of the capacitor (C) in centrifugal switch speed control method of universal motor? Maintain constant speed Improve the power factor Protect from the over loading Reduce the sparks on the contacts None 475. Which type of winding wire is used for rewinding submersible pumps? Pvc covered copper wire Super enamelled copper wire Single cotton covered copper wire Double cotton covered copper wire None 476. Which type of AC single phase motor having low starting torque? Induction start induction run motor Capacitor start induction run motor Capacitor start capacitor run motor Resistance start induction run motor None 477. What is the function of centrifugal switch in single phase motors? Maintain constant speed Break the starting winding Break the running winding Protect the motor from over loading None 478. which is the application of universal motor? Jet pump Food mixer Teleprinter Compressor None 479. Which single phase motor is fitted with wound rotor? Repulsion motor Shaded pole motor Permanent capacitor motor capacitor start capacitor run motor None 480. What is the relation between running winding and starting winding of a single phase induction motor with respect to resistance? Both resistances will be equal Running winding is less, starting winding more Running winding is more, starting winding less Running winding is less, starting winding infinity None 481. What is the function of the part marked as x in shaded pole motor? Increase the efficiency Maintain constant speed Initiate the rotor movement Strengthen the magnetic field None 482. How the direction of rotation of a capacitor start induction run motor is reversed? By changing the supply terminals By changing the capacitor connections By interchanging main winding terminals By interchanging both main and auxiliary winding terminals None 483. which single phase motor tapped field speed control method is employed? Universal motor Shaded pole motor Capacitor start induction run motor Capacitor start capacitor run motor None 484. Which type of single phase induction motor is used in food mixer? Universal motor Repulsion motor Shaded pole motor Permanent capacitor motor None 485. What is the angular displacement between starting and running winding of a single phase induction motor? 45 electrical degree 60 electrical degree 90 electrical degree 120 electrical degree None 486. Why the hysteresis motor is suitable for sound recording instruments? Small in size High efficiency Noiseless operation Less error operation None 487. Which motor is preferred for domestic water pumps? Universal Motor Repulsion motor Shaded pole motor Capacitor start motor None 488. Which type of motor has relatively small starting torque? Universal motor Capacitor start capacitor run motor Capacitor start induction run motor Resistance start induction run motor None 489. What is the function of centrifugal switch in split phase motor? Protects from over current Maintains constant speed Protect the motor from over loading Make and break the starting winding from supply None 490. How to produce starting torque in a shaded pole fan motor? Using rings on poles Using capacitor on winding circuits Interchanging cage rotor windings by switch Interchanging the field coil windings by switch None 491. What is the reason to use a permanent capacitor in fan motor circuit? Speed regulation Lower power consumption Splitting of phase for torque Controlling electrical interference face None 492. Which motor is having half coil winding? Mixer Grinder Ceiling fan Washing machine None 493. Why running winding is placed in the bottom of the core? To get low resistance To get low inductance To get high resistance To get high inductance None 494. Calculate the slot distance for a ceiling fan having 28 slots, 14 poles, 14 coils in half coil connection? 90° 120° 180° 240° None 495. Which type of single phase motor is having very high starting torque than any other type of single phase motor? Universal motor Reluctance motor Repulsion start induction run motor Capacitor start induction run motor None 496. What is the application of shaded pole motor? Hair dryer Ceiling fan wet grinder Washing machine None 497. Which type of single phase motor is used for hard disk drives? Stepper motor Repulsion motor Hysteresis motor Reluctance motor None 498. What is the function of centrifugal switch used in capacitor start, capacitor run induction motor? Disconnect the running winding after reached 75% to 80% speed Disconnect the starting winding after reached 75% to 80% speed Disconnect the starting capacitor after reached 75% to 80% speed Disconnect the starting and running winding after reached 75% to 80% speed None 499. Which type of single phase motor is having very high starting torque than any other type of single phase motor? Universal motor Reluctance motor Repulsion start induction run motor capacitor start induction run motor None 500. Where the capacitor is connected in a single phase permanent capacitor motor? In series with starting winding In series with running winding In parallel with starting winding In parallel with running winding None 501. Which motor is used in table fan? Universal motor Shaded pole motor Eddy current motor Permanent capacitor motor None 502. What is the effect, if coil group connection is wrongly connected in a single phase motor rewinding? Motor runs slowly Motor will not run Motor runs in very high speed Motor runs and takes more current at no load None 503. What is the effect in a repulsion motor, if the magnetic axis shifted to another side? Direction of rotation will change Direction of rotation remains same Motor speed increases from rated speed Motor speed will reduce from rated speed None 504. What is the effect if the centrifugal switch is not disconnected after the motor starts? Motor will run normally Motor will stop immediately Starting winding will burn out Motor will run very slow speed None 505. How the direction of rotation of repulsion motors is to be reversed? By shifting the brush-axis By interchanging the supply terminals By changing the main winding terminals By changing the compensating winding terminals None 506. Why a capacitor is connected across centrifugal switch in the centrifugal switch speed control method? To maintain constant speed To protect from over loading To improve the power factor To reduce the sparks in contacts None 507. None 508. What is the effect, if some slots in a split phase motor left out without winding after completion of concentric winding? works normally Reduction in speed Reduction in torque Runs with very high speed None 509. Which supply indicates by the color of | conductor exhibited on Red, Blue and Black? Supply DC 3 wire system 3 Single phase Ac system Supply AC system 3 phase Apparatus AC system 3 phase None 510. Which cable ties are used to bunch the wires? Silk ties P.v.c ties Nylon ties Cotton ties None 511. Which device is avoided in the panel board assembly? Sensors Indicating lamp Isolating switch Push button switch None 512. What is the name of the device marked as ‘X’? Stop button Start button Main contact Auxiliary contact None 513. What is the name of the wiring accessory DIN rails G channel Grommets Race ways None 514. What is the name of the device marked as ‘X’ in the circuit? Contactor No volt coil stop button Overload relay trip None 515. What is the name of the accessory used in control panel wiring? Wire ferrules Wire sleeves Nylon cable ties Cable binding strap None 516. What is the name of the accessory used in control panel wiring? Lugs Thimble Grommet Terminal connector None 517. which device protects from overload and short circuit in a panel board? Isolating switch Time delay relay| Thermal overload relay Miniature circuit breaker None 518. Which switch with an actuator is operated by the motion of a machine or part of an object Limit switch Toggle switch Isolating switch Push button switch| None 519. What is the reason for providing two separate Earthing in panel board? Panel board is made in metal box Control the stray field in the panel Reduce the voltage drop in panel board Ensure one earthing in case of other failure None 520. Which circuit, the limit switches are used? Lift circuits Street lighting Motor control circuits| Domestic power circuits None 521. How the control circuit voltage and power in a contractor are to be selected? As per rated current As per supply voltage As per no volt coil rating As per the type of supply None 522. Which accessory is used to mount MCB,OLR in the panel board without using screws? DIN Rail G. channel Grommets Pvc channel None 523. Which type of device protects motors from overheating and overloading in a panel board? Rectifier Limit switch Thermal relay Electro mechanical relay None 524. What happens, if time delay relay of a auto star delta starter still in closed condition after starting? Starts and stop Runs normally Runs in star only Runs in delta only None 525. What is the use of PVC channel in a control panel wiring? Mounting MCB Mounting relays Path way for electrical wiring and protection Mounting double deck terminal contactor None 526. Which device controls the operations in sequential control systems? Timer Relays Contactor Control transformer None 527. Why sequential control of motors is required in an industrial application? To share more loads To reduce power consumption To minimize the operating cost To increase the accuracy of operation None 528. What is the purpose of control transformer used in control panel wiring? To maintain constant terminal voltage To supply the power to the auxiliary circuits To control the supply voltage to the contactor To protect the control elements from over voltage fault None 529. What essential feature to be considered | while designing a layout of control panel? Proper type of protection and measuring system Inside area and number of indicating lights in front panel Suitable method of labeling and cable harnessing Outside dimensions and swing area of cabinet door None 530. How the contacts in a contactor can be engaged for working? By manual operation By mechanical settings By operating electromagnet to change the position By using bimetallic strip to change the position None 531. Why power and control wiring run in separate raceways? To reduce heat To reduce the radio interference To increase the insulation resistance To increase the current carrying capacity None 532. Which device prevents flare out of stripped and stranded cables in the panel board? Sleeves Wire ferrules Lugs and thimbles Cable binding straps and button None 533. What is the use of G' channels in control panel?| For fixing relays| For fixing contactors For fixing instruments| For fixing terminal connectors None 534. What is the function of limit switch in control panel wiring? Controls machine from over heat Controls machine from over speed Controls machine from over loading Controls distance movement of any machine None 535. Which is the standard duty cycle code of the contactor for starting and stopping the AC resistive and inductive load? AC1 AC2 AC3 AC4 None 536. Which is the correct sequence operation of contactors for operating automatic star delta starter? Main →Star→Delta→Timer Star → Main→Timer→Delta Main→ Timer→Delta→Star Star→ HTimer→Main→Delta None 537. Why control panels are provided with control transformer? To maintain rated voltage to load To operate the auxiliary circuits To maintain rated main supply voltage To supply reduced voltage to power circuit None 538. What is the purpose of thermal overload relay in control panel? switching ON/OFF the circuit Protect the circuit from earth fault Control the circuit based on time delay Protect the motor from overheating and loading None 539. Which resistor is used to measure light intensity? VDR NTC PTC LDR None 540. Which code indicates silicon semiconductor diode? OA79 BY 126 IN 4007 2N3055 None 541. What is the input ripple frequency (Fin) of full wave rectifier? Fin = 1⁄2 F Fin = Fin Fin = 2 Fin Fin = √2 Fin None 542. Which is a active component? Inductor Resistor Capacitor Transistor None 543. Which letter indicates the compound material cadmium sulfide? A B C R None 544. What is the name of the symbol? | Two input OR gate Two input AND gate Two input NOR gate Two input NAND gate None 545. which is a passive component? Diac Diode Transistor Capacitor None 546. What is the name of the device symbol? SCR IGBT DIAC TRIAC None 547. How many characters are in hexadecimal number system? 6 8 12 16 None 548. which electronic circuit generates A.C signal without input? Filter circuit Rectifier circuit Amplifier circuit Oscillator circuit None 549. Which instrument provides a visual representation of measured or tested quantities? Voltage stabilizer Function generator Cathode ray oscilloscope Cathode ray oscilloscope None 550. What is the minimum voltage required in the base emitter junction to conduct a silicon transistor? 0.2V-0.3V 0.4V-0.5V 0.6V-0.7V 0.81-0.9V None 551. What is the minimum and maximum value of resistor with four colour bands, red, violet, orange and gold respectively? 237500-262500 Ohm 247000-273000 Ohm 247000-273000 Ohm 224000-336000 Ohm None 552. What is the reason for barrier voltage is more in silicon material? Lower atomic number Resistance is very low Doping percentage is more Valence electrons are two only None 553. What is the reason for widened barrier in a reverse biassed diode? Minority carriers in two materials are neutralised Electron in N material is drifted to positive terminal Holes in P material attracted to negative terminal Electrons and holes are attracted towards supply terminals None 554. which is the advanced version of power electronic component used in the output stage in drives? FET UJT SCR IGBT None 555. Which logic gate refers the truth table? OR gate NOT gate AND gate NOR gate None 556. Which quantity can be measured by CRO? Frequency Inductance Resistance Power factor None 557. Which is the main application of SCR? Amplifier Oscillators Multi vibrators Speed control of motors None 558. Which doping material is used to make P-type semiconductor? Boron Arsenic Antimony Phosphorous None 559. which type of biasing is required to a NPN transistor for amplification? Base ground, emitter and collector positive Base negative, emitter positive and collector negative Base positive, emitter negative and collector positive Base positive, emitter negative and collector negative None 560. What is the type of function in the transistor circuit? Switching Oscillation Modulation Amplification None 561. Why negative feedback is required in amplifier circuits? To reduce the distortion To increase the amplification factor To increase the output voltage gain To increase the output current gain None 562. What is the purpose of DIAC in power control circuits? As rectifier For triggering As an oscillator For amplification None 563. Which type of control device is used in electronic fan regulator control circuits? FET UJT DIAC DIAC None 564. Which quadrant operation of SCR delivers heavy current in reverse biasing? First quadrant Third quadrant Fourth quadrant Second quadrant None 565. What is the use of time-base control switch or knob in the CRO? Select sweep speed Select input voltage range Select input signal voltage| Select intensity of the beam None 566. Why a snubber circuit is used in the TRIAC motor control circuit? To avoid false triggering To increase the life of TRIAC To increase the motor torque To maintain the motor speed constant None 567. Why most of semiconductor devices are made by silicon compared to germanium? High barrier voltage High resistance range High thermal conductivity High current carrying capacity None 568. What is the characteristic property of base material in a transistor? Lightly doped and very thin Heavily doped and very thin Lightly doped and very larger Heavily doped and very larger None 569. What is the type of amplifier? Push Pull Amplifier Common Base Amplifier Emitter Follower Amplifier Common Emitter Amplifier None 570. What is the output voltage if the centre tap of transformer is open circuited in a full wave rectifier circuit? Zero voltage Full rated output Half of the rated output one fourth of rated output None 571. Which oscillator provides high accurate stable frequency? Hartley oscillator Colpitts oscillator Quartz crystal oscillator R.C. phase shift oscillator None 572. What is the main application of a Field Effect Transistor (FET)? Voltage control device Current control device Positive feedback device Low input impedance device None 573. Which multi vibrator produces a repetitive pulse waveform output? Astable multi vibrator Bistable multi vibrator one shot multi vibrator Monostable multi vibrator None 574. What is the main function of Uni Junction Transistor (UIT)? Relaxation oscillator Broadcast transmitter Loudspeaker amplifier Microphone input device None 575. How is the gate terminal of N channel JFET biased? Gates are reverse biased Gates are forward biased Gates are forward biased with drain Gates are reverse biased with source None 576. What is the main advantage of a class A amplifier? Minimum distortion Maximum current gain Maximum voltage gain Minimum signal to noise ratio losses None 577. Which device is made up of using the methods of point contact, grown, diffusion and alloy junctions? Inductor Resistor Capacitor Transistor None 578. Which electronic circuit produces signal waves or pulses without an input? Detector Amplifier Oscillator Modulator None 579. Why the collector region is physically made larger than emitter region in a transistor? It has to dissipate more heat Output taken from collector terminal Base collector region is reverse biased Collector region always operate with high voltage None 580. Which circuit is essential to maintain oscillations or waves in an oscillator circuit? Rectifier with filter Voltage multiplier Negative feedback Positive feedback None 581. Which device has very high input impedance, low noise output, good linearity and low inter electrode capacity? NPN transistor PNP transistor Field effect transistor Uni junction transistor None 582. VWhat is the difference in current control of MOSFET compared to JFETs? Insulating layer instead of junction Using N material instead of P material Using P material instead of N material Using N material gate instead of P material None 583. What is the type of amplifier circuit? Common base amplifier Common emitter amplifier Class B push pull amplifier Common collector amplifier None 584. What is the peak voltage of 220v rms AC voltage? 310.02V 311.17V 312.25V 315.20V None 585. What is the frequency of the displayed signal on CRO screen covered by 5 division with a time base setting of 0.2 microseconds? 1.0 KHz 10.0 KHz 100.0 KHz 1000.0 KHz None 586. which control system consumes very low power for motion control in AC and DC motors? Field control Drives control voltage control Armature control None 587. Which drive is classified according to mode of operation? Group drive| Manual drive Individual drive Continuous duty drive None 588. What is the name of the characteristic curve in D.C drive? Speed vs torque characteristic Torque Vs field current characteristic Speed Vs armature current characteristic Field current Vs armature current characteristic None 589. What is the name of the component marked as 'x' in the block diagram of AC drive? Rectifier D.C bus Inverter A.C motor None 590. What is electric drive? device used as prime mover for generator A device converts A.C to D.C supply An electromechanical device for controlling motor A machine converts mechanical energy into electrical None 591. What is the full form of B.O.P in DC drive? Bridge Operation Panel Basic Operational Panel Basic Operation Program Bridge Operator Program None 592. which is the classification of drive according to dynamics and transients? Short time duty drive Intermittent duty drive Automatic control drive variable position control drive None 593. What is the function of power controller in drive circuits? It sounds an alarm in no load conditions It detects the overloading condition of motor It reduce motor current during transient operation it maintain the torque at low voltage conditions None 594. Why it is necessary to keep V/F ratio constant in a drive? Keep the stetar flux maximum Maintain the rotor current minimum Maintain the speed of motor constant Maintain the rated torque at all speeds None 595. Which power modulator used in the electric drive system? cyclo converters Frequency multiplier Phase sequence indicator Servo controlled voltage stabilizer None 596. Which type of sensing unit employed in drive system? Opto coupler Speed sensing Photo voltaic cell Resistance temperature detector None 597. Which type of machine in industries is provided with multi motor electric drive? Rolling machine Air Compressor Shearing machine Heavy duty electric drilling machine None 598. Which control system is used for Eddy current drives? Slip controller Rectifier controller Ac voltage controller| Dc chopper controller None 599. What is the purpose of JOG key in control panel of D.C drive? Stop the motor Restart the motor Inching operation Reverse the direction of motor None 600. What is the purpose of LCD on basic operator panel in DC drive? Indicate the fault Display the speed Monitor the parameter Display availability of supply None 601. What is the reason of using shielded cable drives? Easy for connection Good appearance Protects from mechanical injuries Eliminates the electrical interference None 602. If the axis of a moving coil is kept parallel to the flux then the e.m.f. induced in the coil will be minimum maximum nil one volt None 603. By rotating a conductor in a magnetic field, the induced e.m.f. will be static dynamic induced e.m.f. none of the above None 604. For inducing an e.m.f. of 1 volt in 1 second time, a conductor will have to cut: 10 maxwell lines 10 lines 1 weber magnetic flux none of the above None 605. On doubling the supply frequency, the eddy current will: become half of their former value become four times of their former value remain unaffected ecome eight time of their former value None 606. In order to reduce hysteresis losses, the cores of electrical machines are generally made of tungsten steel ) cast iron high carbon steel silicon steel None 607. The law which states that the induced e.m.f. and current always opposes the cause producing it was presented by: Lenz Maxwell Faraday Ohm None 608. Degaussing is the process of: removing gases from a material removing impurities from magnetic materials demagnetising a metallic part demagnetising a magnet None 609. Which of the following statements is incorrect: Whenever the flux linking through a coil or a circuit changes, e.m.f. is produced The direction of dynamically induced e.m.f. can be determined by applying Fleming's right-hand rule Coefficient of coupling for tightly coupled coils is zero The coefficient of self inductance is proportional to the square of the number of turns on it None 610. Whenever a conductor cuts magnetic flux, an e.m.f. is induced in the same. The statement refers to Joule's law Coulomb's law Faraday's law Lenz's law None 611. The given figure shows a coil with a closed iron core. What do the dotted lines represent ? magnetic potentia magneto motive force magnetic field strength magnetic flux None 612. The magnetic flux shown in above Fig. can be increased by increasing the magneto motive force decreasing the magneto motive force reversing the direction of current making an air-gap in the core None 613. An open-circuit curve is drawn between None 614. . In a level compound generator, full load voltage is found to be the terminal voltage lesser than higher than equal to much lesser than None 615. In which type of d.c. machine-poles is residual magnetism necessary ? Shunt generator ( Motor Separately excited generator Permanent magnet type generator None 616. Armature cores are commonly made of iron silicon steel high carbon steel stainless steel None 617. Lap winding has parallel paths. two four equal to the no. of poles one None 618. the output voltage of a single loop generator is a steady d.c steady a.c. pulsating a.c ) pulsating d.c None 619. The voltage generated by a generator is determined by the equation: None 620. What effect on the current flow takes place on reversing the direction of movement of a conductor in the magnetic field of a generator? no effect takes place current flow is stopped the direction of current flow is reversed the magnitude of current flow is decreased None 621. In most generators the output voltage is induced by rotating magnetic field past stationary coils relative motion between the field and the armature coils converting electrical energy into mechanical energy rotating the coils around a magnetic field None 622. The shunt field of a compound generator is connected across both the series field and the armature. This connection is known as: long shunt short shunt differential compound cumulative compound None 623. . For all symbols having their usual meaning, the e.m.f. genarated in a lap wound generator is given by : None 624. The brushes are always placed along: MNA (magnetic neutral axis) GNA (geometric neutral axis) perpendicular to MNA perpendicular to GNA None 625. The function of compensating winding is to neutralise: reactance voltage generated as a consequence of commutation cross-magnetising the effect of armature reaction demagnetising effect of armature reaction all the above None 626. . In any d.c. generator, the e.m.f. generated in the armature is maximum when : rate of change of flux is minimum rate of change of flux is maximum flux linked with conductors is maximum ) flux linked with conductors is minimum None 627. The method which can be used to improve commutation process is: ) to increase the resistance of brushes to reduce the no. of turns in the armature coil so as to reduce the no. of commutator segments to neutralise the reactance voltage by producing a reversing e.m.f. in the short-circuited coil under commutation all the above None 628. The function of interpoles is: to neutralise the reactance voltage to help commutation process to neutralise the cross-magnetising effect of armature reaction to reduce sparking at the commutator all the above None 629. Shunt generators are used where the main requirement is a constant voltage and current current voltage over a wide load range voltage over a narrow load range None 630. enerators are run in parallel for achieving the advantage of ) high reliability high efficiency meeting higher load demands all the above None 631. . Interpoles are normally connected in: ) parallel with the field windings series with the field windings parallel with the load series with the load None 632. In d.c. generator, which loss varies with the load? copper loss eddy current loss hysteresis loss windage loss None 633. The armature of d.c. generator is laminated to reduce the overall mass insulate core reduce the eddy current loss all the above None 634. In d.c. generators, the cause of rapid brush wear may be: imperfect cantact severe sparking rough commutator surface any one of the above None 635. In d.c. generators, lap winding is used for low voltage, low current ) high voltage, high current low voltage, high current high voltage, low current None 636. D. C. generator preferred for charging automobiles batteries is shunt generator series generator long shunt compound generator short shunt compound generator None 637. . The overall efficiency of a d.c. generator lies in the range of: 60-80% 80-90% 75-85% 85-95% None 638. The function of an equalizer ring is to avoid unequal distribution of current at the brushes to help in reducing sparking both the above none of the above None 639. The carbon brushes of D. C. machines become shorter by wearing out during the running time of the machine. At which length do you have to change the brushes? 1/2 of the original length 1/3 of the original length 3/4 of the original length 2/3 of the original length None 640. . A2 kW, 200 V. D. C. generator will supply a load current of: 2 amps 4 amps 10 amps 20 amps None 641. The essential condition for stable parallel operating of two D.C. generators having similar characteristics is that, they should have same kilowatt output ratings drooping voltage characteristics same percentage regulation same no load and full load speed None 642. D.C. generators are connected to or disconnected from the busbar only under the floating condition. This is done to avoid ( burning of switch contact sudden loading of the prime mover mechanical jerk to the shaft all of the above. None 643. For parallel operation the D.C. generators normally preferred are Shunt and over compound adjust speeds of their prime movers use equalizer connections. None 644. Equalizer bar is necessary for parallel operation of D.C. series and over compound generator under compound generator shunt and series generator over compound generator None 645. D.C. shunt generators are most suited for stable parallel operation because of their voltage characteristics identical dropping linear rising None 646. Two parallel shunt generators will divide the total load equally in proportion to their kilowatt output ratings only when they have the same rated voltage voltage regulation internal, R, drops both A and B None 647. The simplest way to shift load from one D.C. shunt generator running in parallel with another is to....... adjust their field rheostats insert resistance in their armature circuits adjust speeds of their prime movers use equalizer connections None 648. n case of parallel operation of D.C. compound wound generators, for proper division of load, from no load to full load, it is essential that they should have the same kW output rating percentage regulation series field resistance speed of operation None 649. In parallel operation of two D.C. compound generators provided with interpoles, the equalizing bar must be connected to interpole fields only series fields only junction of series and interpole field none of the above None 650. The main function of an equalizer bar is to make the parallel operation of two over compounded D.C. generator stable possible regular smooth None 651. the main factor that leads to unstable parallel operation of flat or over compounded D.C. generator is....... their rising voltage characteristics unequal series field resistances unequal speed regulation of their prime movers their drooping voltage characteristics None 652. . The formula to find EMF induced (E) in DC generator is None 653. In the fleming's left hand rule the thumb represents the direction of motion of the conductor the direction of flux the direction of current flow in the conductor the voltage in the conductor None 654. By which law, the direction of the induced e.m.f. will be identified? Faraday's first law of electromagnetic induction Faraday's second law of electromagnetic induction Lenz's law Fleming's left hand rule ( None 655. Fleming's Right Hand Rule is to identiy the ) direction of flux direction of rotation of a generator direction of current in a motor direction of induced em.f None 656. A DC generator works on the principle of faraday's law of electrolysis flemings left hand rule lenz law faradays law of electromagnatic induction None 657. . A 6 pole DC generator has wave wound armature. If the armature is rewound for lap, the induced EMF will be increased by 6 time decreased by 6 times increased by 3 times decreased by 3 times None 658. The Insulating materials used between the commutator segments of a DC generator will be paper fibre wood mica None 659. . Interpoles are provided in DC generator for increasing the emf of the generator increasing the counter emf reducing the strength of the main field flux reducing the sparking at the commutator segment None 660. In a DC generator, sparking at the brush position may be: due to over commutation due to under commutation Both (a) and (b) Neither (a) nor (b) None 661. In a DC Generator, if the field circuit resistance is more than the field critical resistance, then the generator will build up maximum voltage generator will generate maximum voltage generator will not build up the voltage ) field coils will burn None 662. . Brush tension in a DC generator plays very important role in its performance. Excessive brush tension may... slow down the speed of the machine decrease the output voltage increase the output voltage overheat the commutator and wear out the surface None 663. The purpose of lamination between core is used in armature is to............ increase the induced e.m.f reduce the eddy current loss reduce the copper loss reduce the armature reaction effect None 664. The load characteristic of separated excited generator is between armature current and emf armature current and terminal voltage load current and terminal voltage field current and terminal voltage None 665. The purpose of the flexible copper pig tail mounted on the brush of the D.C. generator is............. ( to collect current from the commulator to facilitate collection of current from the armature conductors to convey the current from the brushes to the holder to prevent the brush from flying out under the centrifugal force None 666. By providing compensating winding in series with armature of a D.C. generator which defect can be prevented? Rough commutation Cross magnetizing effect Demagnetizing effect Armature resistance drop effect None 667. As per B.I.S., the series field winding terminals must be marked as B.: B E, E D, D₂ F.; F₂ None 668. Which among the following is the function of the inter-poles in a DC generator Neutralisation of statically induced voltage To make sparkless commutator To change rough to smooth commutation All of the above None 669. Which type of D.C. generator is used for welding generator set? ( D.C. shunt generator D.C. series generator D.C. Differential compound generator D.C. cumulative compound generator None 670. Which type of DC generator is used for welding generator set? DC series generatoR DC shunt generator DC differential compound generatoR DC Cummutative compound generator None 671. How many parallel paths in simplex wave winding armature of the D.C. generator, which is having 8 poles? 2 4 6 8 None 672. A pulley of DC generator is found to have completed 2000 revolutions within 1.25 minutes. The speed of the DC generator in r.p.m. will be: 1200 r.p.m 1400 r.p.m 1600 r.p.m 2000 r.p.m None 673. The 10 pole D.C generator has 960 armature conductors and a flux per pole of 20 mwb running at 600 rpm. Calculate the e.m.f generated when the armature is connected in simplex wave winding? 640 volts 960 volts 720 voltS 360 volts None 674. 8. Which type of D.C. generator is called as constant voltage generator ? D.C. series generator D.C. shunt generator D.C. Long shunt compound generator D.C. short shunt compound generator None 675. The DC shunt generator is not building up voltage. The reason is field winding open residual magnetism available in the field poles generator running at the rated speed generator runs in the correct direction None 676. Which among the following statements is not correct? The best method of stopping a DC shunt generator is to open the field circuit switch The existence of residual magnetism is must in a self-excited DC generator As the shunt field current increases, the induced voltage also increases initially As the speed of the DC generator increases, the induced voltage also increases up to a certain extent None 677. The differential compound D.C. generator could be changed to an over compounded generator by changing the connection of the series and shunt field series and armature fields armature series field None 678. Which type of D.C compund generator is suitable for electroplating purpose? cumulative over compounded generator cumulative flat compounded generator cumulative under-compounded generator differential compounded generator None 679. The generators are designed to deliver full load current (,) and the fall of no-load voltage will be about.......... 5 to 8% 3 to 6% 4 to 7 % 2 to 5% None 680. Which type of generator gives a constant voltage output at all loads? Level compound generator Commutative compound generator Differential compounded generator Series generator None 681. None 682. The one of the applications of under compounded DC generator is... for electroplating for welding generator ) for street lights for railways None 683. Which one the following is the application of over compounded DC generator? Electroplating Railways Welding generator Lathes None 684. The generator in which the shunt field is connected after the series field is called.. D.C series generator D.C shunt generator D.C short shunt compound generator D.C long shunt compound generator None 685. One of the main reasons for NOT building up the voltage in D.C. generator is the generator runs at rated speed the field circuit resistance is more than field critical resistance the residual magnetism existing in the field cores brushes are in proper contacts None 686. The rough commutation of the D.C. generator armature can be reduced by providing compensating winding in the main pole faces shifting brush position from GNA to MNA providing inter poles between the main poles using low resistance brushes None 687. What is normally used to convert the alternating voltage produced by rotating a coil in a magnetic field into a direct voltage ? Regulator Semi conductor rectifier Commutator Transformer ( None 688. In DC generator, the commutator is made up of.... brass hard drawn copper ) bronze steel None 689. The function of brushes in the DC generators convert AC into uni-directional current collect the current from the commutator increase the magnetic flux connect the armature and commutator None 690. In DC generator, the number of segments and commutator is equal to the number of.... poles armature coils parallel path brushes None 691. When conductors are stationary, to induce an e.m.f. dynamically, It is necessary to..... increase the flux around the conductor decrease the flux around the conductor rotate the magnetic field over the conductor set the pole and armature to touch each other None 692. Which one of the following is the reason for loosing the residual magnetism of self excited DC generator? The armature core is not properly laminated The generator is kept idle for a long time The armature resistance is more than 1 ohm Incorrect brush position None 693. The cross magnetizing effect of armature reaction in DC generator can be nullified by....... inserting compensating winding providing inter poles between the main pole shifting the brush position from GNA to MNA increasing the ampere- turns in the field winding None 694. The insulating material used in between. Info commutator segment is.... ebonite mica ) empire glass None 695. The yoke for large D.C. machine is made out of high carbon steel cast steel mild steel wrought iron None 696. The pole core of a DC generator is made of mild steel cast iron copper aluminium None 697. The thickness of lamination of armature core discs is 0.3 mm ) 0.4 mm 0.5 mm 0.6 mm. None 698. As per BIS the shunt field winding terminals of separately excited type DC generator are marked as D1, and D, 2 B, 1 and B,2 F1, and F2 E1, and E2 None 699. In a self excited generator, the excitation is provided by its armature its field battery another generator None 700. In DC generator, the shunt field contains many turns of thin wire, it has a.... zero resistance low resistance high resistance medium resistance None 701. In a long shunt compound generator, the terminal voltage is 400 V, the shunt field resistance is 80 ohms. Calculate the shunt field current? 3.2 amp 4.0 amp 5.0 amp 5.5 amp None 702. A long shunt compound generator delivers a load current of 100 A at 400 V, the shunt field resistance is 200 ohm. Calculate the armature current? 100 A 102 A 4A ) 2 A None 703. Which one is the main condition for paralleling of DC generators? The capacity of both generators must be same The field critical resistances must be same The polarities of both generators must be same The maximum efficiency of both generators must be same None 704. The yoke of a DC machine is made of - Copper Carbon ( Cast Iron Silicon steel None 705. . Body or yoke of a D.C. generator is made of.... Cast iron Cast steel Rolled steel All of these None 706. The yoke of D.C. machine is made of..... Aluminium Copper Silicon steel Cast steel None 707. Which of the following is a function of yoke? To provide strength to the core To support field winding To provide a return path to the flux To distribute the flux uniformly None 708. In DC machine, yoke offers Mechanical protection to the machine Flux path completion Produce working flux Mechanical protection to the machine or flux path completion ( None 709. The field coils of D.C. machine are made up of .. Carbon Copper Steel Mica None 710. The brushes of D.C. machines are made up of... Brass Carbon Iron Mica None 711. In a D.C. machine, brushes are placed Along geometrical neutral axis Along magnetic neutral axis Between two adjacent poles All of these None 712. In a D.C. machine, the number of brushes in lap winding is always: Double the number of poles Same as the number of poles Half the number of poles Two None 713. A D.C. generator converts A.C. voltages into D.C. voltage using Commutators Carbon brushes ( Shunt coils Series coils None 714. Commutator in D.C. Generator is used for Collecting of current Reduce losses Increase efficiency Convert A.C. armature current into D.C. None 715. The emf produced in the D.C. generator is....... induced emf. Statically ) Dynamically Magnetically Electrostatically None 716. The polarity of induced e.m.f. in a generator can be reversed by reversing the direction of..... Rotation Field flux Both (a) and (b) None of these None 717. The direction of the generated e.m.f. is determined by Lenz's law ) Faraday's law of electromagnetic induction Fleming's left hand rule: Fleming's right hand rule None 718. In Fleming's Right Hand Rule for a D.C. generator conventionally fingers have direction as.. Thumb-motion, index-field, middle current Thumb-motion, index-current, middle-field Thumb-current, index-field, middle motion ( Thumb-field, index-motion, middle current None 719. Which of the following generators are used in arc welding? Shunt generators Series generators Cumulative compound generators Differential compound generators None 720. For D.C. welding sets, the following D.C. generators are brought in practice: Shunt field Level compound ) Differential compound Over compound ( None 721. D.C. generators find its applications in. ) Electroplating ( Rectifiers Elevators All of these None 722. Which of the following windings are necessary in case of all types of D.C. machines? Closed type Lap Wave Open type None 723. In wave winding the parallel paths 'A' is given by.... A=P A=2 A=Z A=4 None 724. The number of parallel paths in wave wound armature are Equal to the number of poles of the machines Equal to two irrespective of the number of poles Equal to number of commutator segment Equal to the number of armature conductors None 725. In a D.C. 4-pole machine, wave winding is used. The number of parallel paths will be: 1 2 4 8 None 726. Commutator pitch of duplex and simplex lap winding are respectively 4 & 2 ) 2 & 1 4 & 1 2&2 None 727. Compensating windings are used in D.C. generator. Mainly to reduce eddy currents by providing local short circuits o provide path for the circulation of cooling air To neutralise the cross magnetising effect of the armature reation None of the above None 728. Interpole windings may be used in D.C. machines to Reduce eddy current losses in pole pieces Provide more field fluxes Reduce armature reaction Increase armature reaction None 729. A D.C. generator is connected to a rated load. The load current flows through which winding of D.C. generator? Field winding Armature winding Both (a) and (b) Either (a) or (b) None 730. Which of the following are variable losses? Eddy current loss ) Hysteresis loss Shunt field loss Armature copper loss None 731. Which of the following reflects the shunt field resistance of a D.C. compound generator? 1.0 ohm 100 ohm 1.5 ohm 1 kilo ohms None 732. In a DC generator the initial flux is produced due to Saturation of the core Residual magnetism Eddy currents Hysteresis None 733. ) In a separately excited DC Generator, the field is connected to In series with an armature Across the armature To the external supply source None of these None 734. In a D.C. machine 64 coils are used. The number of Commutator segments is......... 64 18 32 60 None 735. The effect of armature reaction is a Reduction in EMF ) Increase in iron losses Sparking at commutator Reduction in EMF, Increase in iron losses None 736. The rotational losses in DC, machines is equal to the Kinetic energy of armature ) Rate of change of kinetic energy Square of the kinetic energy of armature Half of the kinetic energy of armature None 737. . Field voltage is independent of armature current in a... Self excited D.C. generator Self excited series field D.C. generator Self excited shunt field D.C. generator Separately excited D.C. generator None 738. Following arrangements are made in a D.C. machine to compensate armature reaction: 144. The effect of armature reaction is a Reduction in EMF Increase in iron losses Sparking at commutator Reduction in EMF, Increase in iron losses None 739. The rotational losses in DC, machines is equal to the Kinetic energy of armature Rate of change of kinetic energy Square of the kinetic energy of armature Half of the kinetic energy of armature None 740. Cross magnetising component of armature reaction is At right angles to the main field m.m.f. Changing direction of main field fluxes At right angles to the demagnetising component All of these None 741. Demagnetizing component of armature reaction is In phase with opposition of main field m.m.f ( In phase with main field m.m.f. Perpendicular to main field m.m.f In phase with cross reaction component None 742. A force will act on a conductor placed in a magnetic field when a current is flowing in the conductor the conductor is rotating the conductor is placed in the magnetic field and it is not carrying a current it is placed at right angle to the field None 743. The back e.m.f. opposes: current applied e.m.f. torque terminal voltage None 744. Back e.m.f. is developed in the armature due to current supply voltage. intersection of the magnetic flux by the armature conductors interaction of the two magnetic fields None 745. The magnitude of E, in a d.c. motor in the start is equal to: zero applied e.m.f. more than applied e.m.f. ) maximum None 746. If in a shunt motor the applied e.m.f. is kept constant then on increasing the load. the shunt-field strength will become its normal value. less than more than equal to zero None 747. In a series motor, the magnetic field-flux stands: proportional to armature current equal to armature current inversely proportional to armature. current constant None 748. The speed of a series motor is very high at no-load because in such state: back e.m.f. is larger armature voltage is lesser flux is very low armature current is very low None 749. A series motor is wound with: fine wire winding nichrome wire winding thick wire winding double wire winding None 750. In a shunt motor, a starter is used for: speed control back e.m.f. control applied e.m.f. control current control in the start None 751. The rotating part of a d.c. motor is known as pole stator rotor armature None 752. In a d.c. machine, a dummy coil is used to: eliminate reactance voltage eliminate armature reaction create a machanical balance in the armature None 753. The rotational speed of a d.c. shunt motor can be increased above its full speed by: increasing the armature current decreasing the armature current increasing the field current decreasing the field current None 754. On increasing the load of a d.c. shunt motor, its speed will remain constant increase proportionately increase slightly reduce slightly None 755. The armature current drawn by a d.c. motor is proportional to: the applied e.m.f. the torque required the flux required the speed of the motor None 756. The power written on the name plate of a d.c. motor is always the power drawn in kVa the power drawn in KW the output power available at the shaft the gross power None 757. The efficiency of an electrical machine will be high if : its losses are minimum its current drainage is minimum the applied e.m.f. is minimum the load is minimum None 758. The direction of rotation of a d.c. motor can be reversed by reversing the supply connections interchanging the armature and field connections adding a resistance in the field circuit reversing the armature connections None 759. The speed of a series motor at no-load is zero 3000 r.p.m. 3600 r.p.m. infinity None 760. . If the back e.m.f. is absent in a d.c. motor then the: motor will run at a very high speed motor will run at a very low speed motor will burn motor will not run at all None 761. By adding a variable resistance across the series field (field diverter) of a d.c. series motor, speed above the normal speed can be achieved because armature current is reduced flux is reduced line current is reduced none of these. None 762. If the field of a d.c. shunt motor gets opened: it will continue to run at the rated speed ( its speed will become very high the motor will stop ) its speed will reduce None 763. When an electric train moves down a hill the d.c. series motor then acts as: d.c. series motor d.c. shunt motor d.c. series generator d.c. shunt generator None 764. Which of the following motors is suitable for high starting torque? Shunt motor Cumulative compound motor ) Series motor Compound motor None 765. Which of the following methods is most economical for finding the no-load losses of a long shunt d.c. motor? Hopkinson's test Swinburne's test Retardation test None of these None 766. The rated speed of a given shunt motor is 1050 r.p.m. To run this motor at 1200 r.p.m., which of the following speed control scheme will be suitable? Armature current resistance control Field resistance control Ward-Leonard control None of these None 767. Which of the following statement is more appropriate? Shunt motor is suitable for electric trains Series motor is suitable for machine tools Series motor is suitable for belt driven machines Compound motor is suitable for fly wheel drive None 768. Which of the following motors is used to drive the constant speed line-shafting lathes, blowers and fans? D.C. shunt motor D.C. series motor Cumulative compound motor Differential compound motor None 769. You notice that a d.c. motor starts with jerk when starting the motor. What may be the fault for this effect? Line voltage too high Short-circuit in the field winding Pitted starter contact terminals Wrong grade of carbon brushes None 770. The speed of a d.c. shunt motor of 3 kW is 2000 r.p.m. when connected to a constant voltage supply. The speed is to be varied upto 2500 r.p.m. What speed control method is to be used? Increasing the back e.m.f. with a resistor Limiting the armature current with a shunt resistor Changing the voltage with a starter Changing the field current by a field rheostat None 771. Starting current of a 220 V, 10 HP, shunt motor having an armature resistance of 0.2 ohm, without starter is: ) 110 Amp. 1100 Amp. 11 Amp. 11000 Amp. None 772. If the current in the armature of a d.c. series motor is reduced by 50%, the torque of the motor will become ) 50% 25% 150% 200% None 773. If the load and flux of a D.C motor are held constant, and the voltage applied across its armature is increased by 5 percent, the speed of the motor will increase by 5 percent decrease by 5 percent not change infinity None 774. You have to change the defective motor of an electric locomotive. Which type of motor would you choose? DC differential compound motor DC shunt motor DC series motor Separately excited motor None 775. . You have to change the defective motor of an electric Locomotive. Which type of motor wouldyou choose? ) Differentially compounded D.C. motor D.C. shunt motor D.C. Series motor Cumulatively compouned D.C. motor None 776. Motor used in electric traction is DC compound DC shunt DC series DC long shunt compound None 777. For which one of the following applications D.C series motor is used? Drives a machine tools and belt drives Rolling milldrives and other drives with load independent speed characteristic Drives that can be started and run in no-load operation Electrical trams or trains and other vehicle drives None 778. What would be the consequence of no load operation of D.C series motor? The motor will come to rest immediately due to low field current The armature current will increase abnormally therefore the fuse would blow The motor will reach such a high speed that the centrifugal force may desiroy the motor windings. ) There will be a decreased field current with the result motor speed will be low. None 779. During the normal operation of a DC series motor, if the field winding is suddenly open-circuited, what will be the effect on the motor ? It will run at slow speed It will run at high speed It will run at normal speed ( It will not run None 780. Which type of motor would you choose for starting the transport vehicles? D.C. Series motor D.C. shunt motor cumulatively compounded DC motor ( differentially compounded DC motor None 781. Which type of motor would you choose for starting the transport vehicle? DC series motor ) DC shunt motor Separately excited DC motor DC differentially compound motor None 782. The back emf of a DC motor depends on the shape of the conductor field flux commutator segments brush material None 783. The E.M.F. induced in a D.C. motor while running, is lo............... assist the applied voltage oppose the applied voltage ) decrease the current increase the current None 784. Calculate the back e.m.f. (E) of a 220 V, D.C Shunt motor. Armature resistance is 0.5 ohm, and armature current is 40 A? 220 V 210 V ( 220 V 190 V None 785. What will be the consequences if the field circuit of a D.C. shunt motor is opened when the motor is running at no load condition? The motor speed will be reduced drastically The torque of the motor will be increased The motor speed could become dangerously high Field current will become zero and hence motor stops None 786. To start a DC shunt motor the type of starter used is 2 point 3 point 4 point Drum type None 787. The connection of NVC in D.C. 3 point starter is across DC supply in series with armature starting resistor overload relay shunt field None 788. In a 3 point starter the No volt coil (NVC) is connected in series with.... armature supply ) starting resistor field None 789. A DC shunt motor connected through a 4 point starter starts normally when the starter handle is moved from OFF position to ON position. But the starter handle does not remain in ON position. One of the reason for the above is open in shunt field protective resistor starting resistor overload coil None 790. For which one of the following applications, D.C. shunt motor is used? Electric trams or trains Electric hoist and cranes ( Drives with high starting torque Machine tool drives None 791. Which type of D.C. motor is preferred for Elevators? D.C. Shunt motor D.C. Series motor Cumulatively compounded D.C. motor Differentially compounded D.C. motor None 792. Which type of D.C. motor is used for elevators? ) D.C. shunt motor D.C. series motor D.C. cumulative compound motor D.C. differential compound moto None 793. Which type of DC motor is used in hoists and cranes? D.C. series motor D.C. shunt motor D.C. cumulative compound motor D.C. differential compound motor None 794. The series field diverter speed control method is mainly used in fan motors electric trains food mixers printing machines None 795. Which method of speed control is mainly applied in electric trains? Series field tapping method Series field diverter method Series parallel method Supply voltage control method None 796. The D.C. motor works on the principle that the current carrying conductor placed in a uniform magnetic field experiences a force on it conductor moves when kept in a uniform magnetic field magnetic field set up by varying current which produces force in the conductor combined magnetic field set up by two current carrying conductors produces a force between them. None 797. the Fleming's left hand rule, the thumb represents the direction of motion of the conductor the direction of flux the direction of current flow in the conductor the voltage in the conductor None 798. Which rule is to be applied to find the direction of magnetic flux? ( Fleming's Right hand rule ) End rule Fleming's left hand rule Cork's screw rule None 799. Which rule is applied to identify the direction of motion of the conductor in D.C. motor? Fleming's left hand rule Fleming's right hand rule Right hand palm rule Cork's screw rule None 800. The direction of rotation of a D.C. motor is determined by Fleming's right hand rule Maxwell's cork screw rule Fleming's left hand rule Ampere's right hand grip rule None 801. . The direction of rotation of a D.C. motor is determined by Fleming's right hand rule Fleming's left hand rule Ampere's right hand grip rule Maxwell's cork screw rule None 802. Which rule is applied to identify the direction of motion of the conductor in DC motor? Fleming's right hand rule Fleming's left hand rule Cork screw rule Right hand thumb rule None 803. Which law is used to find the direction of emf produced in the rotor of a motor? Fleming's right hand rule Fleming's left hand rule Maxwell's cork screw rule Lenz's law None 804. Which of the following D.C. motors has almost constant speed over their full load range? Series ( Shunt Compound (cumulative) None of these None 805. D.C. shunt motors are commonly used in Cranes Electric traction Elevators Lathe machines None 806. D.C. shunt motor is also called as ..... Constant flux motor Variables voltage motor Constant voltage Constant current motor None 807. the direction of armature current in D.C. motor is The same as the generated emf Opposite to that of generated emf Not dependent upon the direction of the armature emf None of these None 808. The armature of D.C. motor is laminated To reduce the mass To reduce the inductor To reduce the eddy current loss To reduce the hystersis loss. None 809. Eddy current loss will depend on..... Flux density Frequency Thickness All of these None 810. The efficiency of D.C. machine is maximum when... Iron losses are equal to mechanical losses Variable losses are equal to constant losses Field copper losses are equal to constant losses Stray losses are equal to copper losses None 811. When the motor runs on no load, then Back emf is almost equal to applied voltage Back emf will be greater than applied voltage Back emf will be less than applied voltage None of the above None 812. n a constant power type load.... Torque is proportional to speed Torque is proportional to square of speed Torque is inversely proportional to speed Torque is independent of speed None 813. For a constant torque load, if the armature resistance of shunt motor is doubled C (keeping the shunt field constant) then the armature current will become Double Halved Remain same ) None of these None 814. A4 Pole, 220 V, 10 H.P., D.C. shunt motor. is rotating at a speed of 320 R.P.M. The developed useful torque will be .. 210. 647 newton metres 215. 547 newton metres 219.484 newton metres None of these None 815. Armature resistance control method is also called as..... Constant current control Constant power control Constant voltage control ) Constant torque control None 816. the current drawn by the armature of D.C. motor is directly proportional to Speed of motor Torque required Voltage across the terminals Armature resistance None 817. Which of the D.C motor uses flywheel? Series Shunt Differentially compounded Cumulative compounded None 818. For same HP rating and full load speed which of the following motor has poor starting torque? Series Shunt Differentially compounded Cumulative compounded None 819. A D.C. series motor is best suited for electrical traction because It develops high starting torque It runs at very high speed It is cheaper in cost It is more rugged in construction like induction motor None 820. D.C.motor useful for trams, cranes, trolley car etc. is... Cumulative compound motor D.C. shunt motor D.C. series motor Differential compound motor None 821. D.C. series motor is best suited for electric traction as It develops high starting torque It is cheaper in cost It consumes less power None of these None 822. Ward-Lenard control is basically a control method Armature voltage Armature resistance Field Field diverter None 823. If starter is not used with large D.C. motor for starting, it will draw a starting current which May damage the armature and commutator Is many times its rated full load current Will provide excessive voltage drop in line All of above None 824. To calculate the efficiency of motor is.... output input x100 output x input output+ input/100 ( output-input/100 None 825. The starting resistance of 3 point starter in D.C. motor is connected with parallel across the armature series with the armature parallel across the field winding series with the field winding None 826. In a four point starter the protective resistor is connected in series with... overload coil no volt coil armature shunt field None 827. The starting current of a 220V, 10HP shunt motor having an armature resistance of 0.2 ohms, without starter is 11 amps ( 110 amps 1100 amps 11000 amps None 828. A 220 V, D.C. shunt motor when runs at 500 rpm, the back e.m.f. (E) is 210 volt and the torque is increased double time the back e.m.f. (E) is 200 V, what is the new speed? 1000 rpm) 500 rpm ( 405 rpm 476 rpm None 829. A 220V DC machine has an armature resistance of 0.5 ohm. If the armature current is 20 amps, the induced emf when the machine works as (i) generator (ii) motor will be........ 230V, 210V 210V, 230V 200V, 230V 190V, 240V None 830. A DC shunt motor is running on no-load if the field winding gets opened, what will be the condition of the motor? The motor will stop The motor will burn out The motor will run at high speed The motor will make noise None 831. In DC shunt motor, if the field is opened during running, what will happen to the motor? The direction of rotation will be reversed The speed will decrease The motor runs in dangerous speed and may burn out The motor will not stop None 832. The D.C shunt motor speed is to be varied from zero to above normal with reversing facility having inherent stability of speed at all loads. What speed control method is to be used? Supply voltage speed control method ) Ward-Leonard system of speed control Shunt field control method Armature speed control method None 833. What is the cause for the DC motor's brush makes chattering or hissing noise during operation? Over loading Insufficient brush tension Short circuit in commutator segment ) Incorrect brush spring pressure None 834. An electrical motor is used for.... Generating power Changing mechanical energy into electrical energy Changing electrical energy into. mechanical energy All of these None 835. None 836. The direction of magnetic field around a current carrying conductor is determined by applying Fleming's left hand rule Right hand thumb rule ( Fleming's right hand rule None of these None 837. Principle of operation of D.C. motor is based on the law: Fleming's left Hand Rule Fleming's Right Hand Rule Right Hand Thumb Rule Lenz's law None 838. The direction of rotation of a D.C. motor can be determine by Ampere's law Fleming's left hand rule Fleming's right hand rule Lenz's law None 839. The e.m.f. induced in the armature of D.C. motor is called.... e.m.f. ) Self induced Back Mutually induced ) None of these None 840. . With the increase in speed of D.C. motor Back emf increases but current falls Back emf falls and current increases Both back emf as well as line current increases Both back emf as well as line current falls None 841. When the armature of a D.C. motor rotates emf induced is Self-induced Back emf Mutually induced emf None of these None 842. With the increases in the speed of a D.C. motor: Both back e.m.f, as well as line current increases Both back e.m.f. and line current falls Back e.m.f. increases, but the line current falls Back e.m.f. falls and line current increases None 843. The induced e.m.f. of D.C. machine is proporational to Field flux only Speed of armature only Number of conductors All of these None 844. Speed of motor is measured by - Ammeter Megger Tachometer Voltmeter None 845. The direction of rotation of D.C. series motor can be reversed by inter changing connections to.. Supply Field Armature Either (b) or (c) None 846. . The direction of rotation of D.C. shunt motor can be reversed by reversing Supply terminals Field terminals Armature terminals Either (b) or (c None 847. The output indicated on the name plate of any motor is always the.... Gross power Power drawn in volt amperes Power drawn in watts Output power at the shaft None 848. A 4-pole, 50 Hz alternator will have a rotational speed of: 750 r.p.m 1500 r.p.m. 3000 r.p.m. 1440 r.p.m. None 849. An exciter used for field excitation of an alternator will be a series generator shunt generator series motor shunt motor None 850. The reason of using laminated cores in the stator of an alternator is to: reduce the weight of the machine reduce the eddy current loss increase the magnetic flux ( increase the eddy current loss None 851. D.C. and A.C. generators are similar in one important respect, that is: the generated e.m.f. is D. C. the generated e.m.f. is pulsating the generated e.m.f. is A. C. the generated e.m.f. is oscillating None 852. A 8-pole alternator rotates at 750 r.p.m. Its per cycle periodic time will be: 10 ms 20 ms. 30 ms 50 ms None 853. Alternators designed to be driven by steam-turbines are built for: high speed operation ) low speed operation medium speed operation both low and medium speed operations. None 854. Sinlge phase portable generators are generally made in the range of: 5000 kVA 1000 kVA 100 kVA 5 kVA None 855. An alternator supplies electric power to various kinds of loads of a factory. If the 10:45 AM phase sequence of the alternator is changed, it will affect the: 3-phase heating circuits 3-phase motor circuits single phase motor circuits ) lighting circuits None 856. The values of pitch factor and distribution factor for an alternator are 0.9 and 0.8 respectively. This will develop an e.m.f. lesser than an alternator having full-pitch coil and concentrated winding by: 0.7 0.72 0.88 0.92 None 857. The winding of a 4-pole alternator is having 36 slots and a coil span of 1 to 8. It is short-pitched by............. electrical degrees. 80 40 20 10 None 858. The number of slip-rings used in a 3 phase, star connected alternator having a rotating armature will be: 2 3 4 6 None 859. The pitch factor is defined as the ratio of the e.m.fs. of the: full-pitch winding to short-pitch winding short-pitch coil to full-pitch coil full-pitch winding to concentrated winding distributed winding to full-pitch winding None 860. The rotor of a salient pole alternator has 12 poles. The number of cycles of e.m.f. in one revolution will be: 2 4 6 8 None 861. In large sized altenators, dampers are used to: reduce current fluctuations reduce voltage fluctuations increase stability increase output e.m.f None 862. The number of electrical degrees which passes through in one revolution of a 6 pole alternator is: 2160 degree 1080 degree 360° 720 degree None 863. The waveform of the e.m.f. generated by an alternator should be: pulse shaped wave square wave sine wave triangular wave None 864. The field circuit of a hydro alternator is supplied with: an A.C. a pulsating current an oscillating current a D.C None 865. When a coil / conductor moves at right angle to the magnetic flux, the induced e.m.f. will be: ) lagging leading maximum zero None 866. Salient pole type rotors as compared to the cylindrical pole type rotors are smaller in diameter and larger in axial length larger in diameter and smaller in axial length larger in diameter and axial length smaller in diameter and axial length None 867. The frequency generated by a 8-pole alternator rotating at 600 r.p.m. will be 20 Hz 40 Hz 60 Hz 80 Hz None 868. The frequency of voltage generated by an alternator having 4 poles and rotating at 1800 R.P.M. is 60 Hz 7200 Hz 120 Hz 450 Hz None 869. A 50 Hz alternator will run at the greatest possible speed if it is wound for poles 8 6 4 2 None 870. When speed of an alternator is changed from 3600 R.P.M. to 1800 R.P.M., the generated e.m.f. per phase will become one-half twice four times one-fourth None 871. The power factor of an alternator is determined by its speed load excitation prime mover None 872. For proper parallel operation, polyphase alternators must have the same kVA rating speed voltage rating excitation None 873. The number of poles in turbo alternator is 2 6 8 10 None 874. The frequency of e.m.f. generated by an alternator depends upon the speed Nand No. of poles is given by PN/ 60 60 N/ P PN/120 120N/P None 875. The current from the stator of an alternator is taken out to the external load circuit through slip rings commutator segments solid connection carbon brushes None 876. In a synchronous machine, the stator frame is made of Stainless steel Aluminium Cast iron or welded steel plates Cast iron or welded steel plates None 877. The stator of an alternator gets overheated due to open phase unbalanced currents in the phases improper alignment of the rotor any one or more of the above None 878. Which type of alternator is used in hydro electric power stations? ( Non salient pole alternator ) Turbo generator salient pole alternator steam turbine alternator None 879. The armature reaction effect in a synchronous machine depends on load current power factor of the load speed of the machine. both A and B None 880. Skew of rotor bar eliminates the effect of space harmonics the entire effect of crawling magnetic noise variation due to unequal force developed on rotor None 881. The alternators are rated in....... kW kVAR ) KVA H.P. None 882. The generated frequency in India is F= 65 Hz ) F= 60 Hz F= 55 Hz F = 50 Hz None 883. The relation between frequency speed and number of poles in Alternator is given as F= PN /60 f= PN /120 F=P/2xN F=Px60/N None 884. A 10 pole alternator rotates at a constant speed of 1200 rpm. The periodic time of voltage in seconds per cycle will be ) 0.01 ( 0.02 0.04 0.08 None 885. The field circuit of an alterator is supplied with an oscillating current a direct current an alternating current a pulsating current None 886. The D.C. and A.C. generators are similar in one important function. That is the generated emf is a direct current generated emf is an alternating current generated emf is a pulsating current generated emf is an oscillating current ( None 887. Adjusting the speed of the prime mover of an alternator is primary necessary. Which one of the following is the reason for this? To get constant frequency To get constant voltage To get increase polarity None of the above None 888. Which one of the following is the reason for using dampers in large alternator work? To increase stability To increase output: To decrease output To reduce voltage fluctuation None 889. The speed of a 6 pole 50 Hz of an alternator is 1800 rpm 1200 rpm. 1000 rpm 600 rpm None 890. The RMS value of emf induced per phase in alternator is given as ......... None 891. A large diameter of alternator is running at slow speed will be having........... rotating alternator rotating field with a smooth cylindrical rotor rotating field with a salient pole rotor rotating armature with field None 892. A 3-phase star connected alternator having a rotating armature will have 2 slip rings 3 slip rings 4 slip rings 6 slip rings None 893. A 3-phase, delta connected alternator having a rotating armature will have 3 slip rings 2 slip rings 4 slip rings 6 slip rings None 894. A 3-phase, star connected alternator having a rotating armature will have 4 slip rings but 3-phase, delta connected alternator having armature will have 6 slip rings 4 slip rings 3 slip rings ) 2 slip rings None 895. What is the type of lamp method illustrated in the figure for synchronizing 3 phase alternators? All dark lamp method All bright lamp method Two bright and one dark lamp method Two dark and one bright lamp method None 896. WHAT IS THE NAME OF THE PART OF AN ALTERNATOR SHOWN IN THE FIGURE salient pole type rotor semi enclosed slot type stator smooth cylindrical pole type rotor totally enclosed slot type stator None 897. Which instrument is used to indicate the correct time for synchronization of two alternators? phase sequence meter synchroscope power factor meter tachometer None 898. The function of synchroscope is to.... ( indicate the correct instant of synchronizing two alternators connect the incoming alternator to the bus bar adjust the frequency of incoming alternator indicate the correct phase sequence of the incoming alternator and bus bar None 899. The reason for the stator core of an alternator is made up of laminated sheets is to... increase the eddy current losses reduce the eddy current losses increase the magnetic flux decrease the speed of the rotor None 900. When the coil moves at right angle to the magnetic flux, the induced emf will be... oscillating minimum zero maximum None 901. The alternators are rated in KVA KW KVAR ampere hour None 902. The most common generated frequency in India is..... 60 Hz 55 Hz 50 Hz 45 Hz None 903. The frequency of 96 pole alternator, running at 1500 rpm is 75 Hz 60 Hz ) 50 Hz 40 Hz None 904. . Find the number of cycles per second of a 6 pole alternator, running at 1000 rpm. 50 cycles/sec 60 cycles/sec 70 cycles/sec 75 cycles/sec None 905. An alternator is running at a speed of 1500 rpm, at the frequency of 50 Hz, calculate the number of poles? 8 6 4 2 None 906. In alternator the factor by which the full pitch voltage is multiplied to get voltage generated in fractional pitch is called as form factor distribution factor pitch factor multiplication factor None 907. The distribution factor (K) of an alternator is expressed as: sin mB 2 K B m.sin! 2 The letter 'm' represents.. number of conductors per phase number of pair of poles per phase. number of poles per phase number of slots per phase per pole None 908. Calculate the percentage voltage regulation of the alternator, when it's terminal voltage rises from 210 volt at full load to 220 volt at no load. 4.76% 4.65 % 4.54% 3.75% None 909. . Alternator converts.... Mechanical energy into electrical energy Electrical energy into mechanical energy A.C to D.C. D.C. to A.C. None 910. An alternator is also called - AC Generator Turbo generator Asynchronous generator. Generator None 911. The frequency of voltage generated by alternators having 8 poles and rotating at 250 R.P.M. is... 60 Hz 50 Hz 25 Hz 163Hz None 912. The power factor of an alternator depends Load Speed of rotor Core losses Armature losses None 913. Under short-circuit conditions, the power factor of an alternator is Unity Almost zero Lagging Almost zero leading Same as normal condition None 914. If the excitation is critical, the power factor of the alternator is Unity power factor Leading power factor Lagging power factor ) None of these None 915. . When excitation is increased (over excited) the synchronous generator operates at Unity power factor Lagging power factor ) Leading power factor None of these None 916. . Quadrature axis synchronous reactance ratio is .. None 917. The percentage of voltage regulation formula of an alternator is.... None 918. Voltage drop in an alternator when under load is due to Armature resistance Armature reactance Armature reaction ) All of these. None 919. In an alternator, voltage drops occur in Armature resistance only Armature resistance and leakage reactance Armature resistance, leakage reactance and armature reaction Armature resistance, leakage reactance, armature reaction and earth connections None 920. A three phase alternator has a phase sequence of RYB for its three output voltages for clockwise rotation. Now if the alternator is rotated anticlocwise, the phase sequence will be RYB RBY BYR None of these None 921. The advantage of salient poles in an alternator is Reduced noise Reduced windage loss Adoptability of low and medium speed operation Reduce bearing loads and noise None 922. The air gap in salient pole machine is Maximum at the centre of pole Least at the centre of the poles and increases while moving away from the centre Maximum at the centre of the poles and decreases while moving away from the centre Equally distributed None 923. Salient pole type rotors are generally och used in Hydro generation power plants. The limiting factor for size of rotor is Rotating field construction Rotating armature construction Centrifugal force acting on the rotating members All of these None 924. Active power of an alternator can be varied by Changing field excitation Changing of prime cover speed Changing the load None of these None 925. In alternators fractional pitch coil are used to reduce the effect of Hunting Harmonics Armature reaction Power factor None 926. Practically in most of the alternators which type of construction is preferred? Rotating field type Rotating armature type Both are equally important None of these None 927. In a synchronous generator, if the mechanical input is increased with constant excitation, the load angle will..... Increase ) Decrease Either increase or decrease None of these None 928. In which of the following loads, armature reactance is magnetising in nature? Pure resistance load Pure inductive load Pure capacitive load R.L.C. load None 929. The diameter and axial length of rotors of a smooth cylindrical type rotors are: Small diameter and small axial length Large diameter and large axial length Small diameter and large axial length Large diameter and small axial length None 930. The slots provided on the armature core of an alternator to house the armature coils are mainly of the following types Open, wide open, closed Open, semiclosed, closed Open, wide open, semiclosed Wide open, semiclosed, closed None 931. Following is true about a cylindrical rotor alternator: Poles are projecting outside Damper winding is required Noise free operation Suitable for slow speed hydro generators None 932. Following statement (s) are true about an alternator Field winding is placed on the rotor, while armature winding is placed on the stator Armature winding has more diameter than field winding Rotor is driven by a prime mover All of these. None 933. . In a synchronous generator V curve is drawn between: ( Field current of the X-axis and armature current on the Y-axis Field current of the Y-axis and armature current on the Y-axis Field current of the Y-axis and power factor on the X-axis Field current of the X-axis and power factor on the Y-axis None 934. Three phase alternator are generally. Star connected Delta connected Open circuited Short circuited None 935. What is/are the necessary conditions for parallel operation of alternators? Terminal voltage is same Frequency should be same Speed of alternators should be same Terminal voltage and frequency should be same None 936. What are the advantages of parallel operation of alternators? Increase in reliability Increases in efficiency under light conditions Continuity in supply is maintained All of these None 937. When two alternators are operating in parallel and at perfect synchronisation, the synchronising power will be.... Negative Infinite Positive Zero None 938. Methods of synchronisation of alternators can be achieved by one or more of the following methods Dark lamp method Bright lamp method Synchroscope method All of these None 939. The synchronous speed of a 2, 4 and 8 poles motor at 50 Hz can not be: 3000 R.P.M 1000 R.P.M. 1500 R.P.M. 750 R.P.M None 940. The no. of poles of a 3-phase induction motor running at 500 R.P.M. will be 12 76 4 2 None 941. The starting torque of a 3-phase induction motor can be increased: by increasing the rotor resistance. by increasing the stator resistance by increasing the air-gap between the stator and the rotor none of these. None 942. At the time of starting, the slip of an induction-motor is equal to: infinite unit zero none of these. None 943. The reason of drawing high current at the time of starting by an induction-motor is: high voltage low power factor zero back e.m.f none of these None 944. For the speed control purpose, pole changing method can be adopted for a: slip-ring motor synchronous motor squirrel-cage induction-motor single-phase motor. None 945. The principle of operation of an induction motor is based on: Faraday's law Rotating magnetic field. Fleming's right-hand rule Ohm's law. None 946. The speed of rotor of an induction-motor is ) the same as the synchronous speed higher than the synchronous speed lesser than the synchronous speed determined by the frequency and the number of poles None 947. To reverse the direction of rotation of a 3 phase induction-motor, it is necessary to: interchange all the three line connections reverse the polarity of the rotor's circuit increase the resistance of the rotor's circuit interchange any two out of the three line connections. None 948. Squirrel-cage induction-motor differs from a slip-ring induction-motor as it has no slip-rings ) rotor windings stator windings rotating part. None 949. Squirrel-cage induction-motor has: ( zero starting torque very small starting torque very high starting torque ( highest starting torque amongst all types of induction motors. None 950. None 951. The purpose of connecting resistance in the rotor circuit of a slip-ring induction motor is to: limit the starting current increase the starting current limit the starting current and to increase the starting torque decrease the starting torque. None 952. . If the induction-motor of a pump is operated at 30% less supply voltage then what will happen? It will start after some time It will continue to run at a lower speed without any damage It will get heated up and consequently will get damaged Nothing adverse will happen. None 953. In an induction-motor, the fractional slip(s) is given by the expression None 954. It is advisable to avoid the use of a (d)O.L. starter for starting an induction-motor having 5 H.P. capacity because the starting torque will be very low the motor will take five to seven times more starting current than its full-load current ) it will pick-up very high speed and may go out of step it will run in the reverse direction. None 955. A thermal overload relay is provided in a starter to protect the motor against: short-circuit open-circuit excess current low voltage None 956. In a 3-phase induction-motor started by a (d)O.L. starter, protection against short circuit is given by the: overload relay no-volt coil back-up fuses protective earth contractor None 957. When a squirrel cage induction-motor is started directly by a (d)O.L. starter, the starting current will be: equal to the full-load current twice the full-load current 3 times the full-load current 5 to 7 times the full-load current. None 958. Figure below illustrates the connections made for identification of termianls of 3 phase induction motor by voltmeter method. дора LINK U 240 V A.C. If the linked terminals are connected as per the figure, the voltmeter V, reads: supply voltage (240 V) ) more than supply voltage less than supply voltage zero volts. None 959. Total electrical degrees for a 4 pole (a) (c) machine is equal to 180° 720° 360° 1080 None 960. The starting torque of a squirrel cage induction motor is low because of: low starting current, low starting P.F. low starting current, high starting P.F. high starting current, high starting P.F. high starting current, low starting P.F. None 961. . If a 3-phase motor runs with two phases only, it is called single phasing. It will ultimately: carry no load Burn out run with triple speed not run efficiently. None 962. On switching 'ON' the starter, the magnetic contractor vibrates heavily. The possible cause is low voltage and single phasing high voltage dirt between the contacts low voltage and dirt between the contacts None 963. A squirrel cage motor of above 3 H.P. should not be started by a D.O.L. starter because: the motor takes 5 to 7 times of its full load current which will spoil the starter the motor will pick up a tremendous speed the motor will have a low starting torque the motor will run in the reverse direction. None 964. Thermal overload relays are than magnetic overload relays. faster slower much bigger very smaller. None 965. Which of the following reduces vibration, chattering, noise, wear and heat in the armature of a starter? ) Electromagnet Shading coil Centrifugal switch Holding lock. None 966. Minimum requirement of contacts in a 3-phase D.O.L. starter is: 4 Nos. 3 Nos. and one No 3 Nos. 2 Nos. and 2 Nos. None 967. NVC used in a starter is meant to protect the motor against: short-circuit open-circuit excess current low voltage None 968. Full load line current of a 3-phase, 3 H.P., 415 V, 50 Hz, squirrel cage induction motor is approximately: 3A 4.5 A 6A 9 a None 969. In a (d)O.L. starter a NVC is connected across a phase and neutral of a 3-phase, 415 V, 50 Hz supply and it works normally. What is the rating of NVC? 220 V ) 230 V 400 V 415 V None 970. A(d)O.L starter can be used satisfactorily for a double cage squirrel cage induction motor upto : 1 kW ) 1.5 kW 3 kW 5 kW. None 971. The purpose of a back-up fuse is to provide protection against: overload over voltage excess current short-circuit None 972. A 4-pole, 3-phase, 50 Hz motor's speed is 95% of its synchronous speed then the actual speed of the motor is: 500 r.p.m 1300 r.p.m. 1400 r.p.m 1425 r.p.m None 973. . The induction motor of a pump is run at a supply voltage 30% lesser than the normal voltage (415 V). The pump starts to work. After some time what possibly can happen? The motor will become hot and will be damaged The motor will start after some time The motor will function normally None of the stated above will happen. None 974. The purpose of adding a rheostat to slip ring induction motor is to limit the starting increase increase the starting current decrease the starting current so that the starting torque may increase none of the stated above. None 975. The rotor current frequency of a slip-ring induction motor depends on: rotor conductor rotor inductance amount of slip inductive reactance. None 976. When the rotor of a slip-ring induction motor is standstill, the rotor frequency is : zero higher than the stator frequency lower than the stator frequency equal to the stator frequency None 977. If the load on a motor is increased beyond its full-load point, the greatest effect of the increase in slip is in increasing the power factor decreasing the power factor increasing the current decreasing the current. None 978. Regarding skewing of motor bars in a squirrel cage induction motor (SCIM), which statement is false it prevents cogging it increases starting torque it produces more uniform torque it reduces motor "hum" duringt its operation None 979. The principle of operation of a 3-phase induction motor is similar to that of a synchronous motor repulsion start induction motor transformer with a shorted secondary capacitor start, induction run motor None 980. The effect of increasing the length of air gap in an induction motor will be to increase the power factor speed magnetising current air gap flux None 981. . In a 3 phase induction motor, the relative speed of stator flux with respect to is zero. stator winding rotor rotor flux space None 982. A 3-phase, 4-pole, 50 Hz induction motor runs at a speed of 1440 R.P.M. The rotating field produced by the rotor rotates at a speed of R.P.M. with respect to the rotor 1500 ) 1440 60 0 None 983. In a 3-phase induction motor, the rotor field rotates at synchronous speed with respect to stator rotor stator flux none of the above None 984. Irrespective of the supply frequency, the torque developed by a SCIM is the same when ever is the same supply voltage external load rotor resistance slip speed None 985. The number of stator poles produced in the rotating magnetic field of a 3-phase induction motor having three slots per pole per phase is 3 6 2 12 None 986. The power factor of a squirrel cage induction motor is low at light loads only low at heavy loads only low at light and heavy loads both ) low at rated load only None 987. A 6-pole, 50 Hz, 3 phase induction motor is running at 950 R.P.M. and has rotor copper loss of 5 K.W. Its rotor input is KW 100 10 95 5.3 None 988. The efficiency of a 3-phase induction motor is approximately proportional to (1-S) S N None 989. A 6 pole, 50 Hz, 3 phase induction motor has a full load speed of 950 R.P.M. At half load, its speed would be 475 500 975 1000 None 990. If rotor input of a SCIM running with a slip of 10% is 100 KW. gross power developed by its rotor is 10 90 99 ) 80 None 991. The fractional slip of an induction motor is the ratio of rotor copper loss to rotor input stator copper loss to stator input rotor copper loss to rotor outpur rotor copper loss to stator copper loss None 992. The torque developed by a 3-phase induction motor depends on the following three factors. speeds, frequency, number of poles voltage, current and stator impedence synchronous speed, rotor speed and frequency rotor e.m.f., rotor current and rotor power factor None 993. The efficiency and power factor of a SCIM increases in proportion to its speed mechanical load voltage ( rotor torque None 994. If the stator voltage and frequency of an induction motor are reduced proportion ality, its locked rotor current is reduced torque developed is increased magnetising current is decreased both A and B None 995. An induction motor has a shaft circuit current 7 times the full load current and a full load slip of 4 percent. Its line starting is 7 1.96 4 49 66 None 996. If stator voltage of a SCIM is reduced to 50 percent of its rated value, torque developed is reduced by percent of its full load value. 50 25 75 57.7 None 1 out of 100 Name Phone Your quiz is running out of time! few seconds are remaining. Time's upTime is Up!
