electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
6751. The term cogging is associated with___________?
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A. induction motors

B. D.C. series motors

C. compound generators

D. three phase transformers

6752. A squirrel cage induction motor is not selected when___________?
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A. all above considerations are involved

B. maintenance cost is to be kept low

C. initial cost is the main consideration

D. higher starting torque is the main consideration
6753. Temperature of the stator winding of a three phase induction motor is obtained by___________?
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A. all above methods

B. embedded temperature method

C. resistance rise method

D. thermometer method

6754. It is advisable to avoid line-starting of induction motor and use starter because__________?
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A. it will run in reverse direction

B. starting torque is very high

C. motor takes five to seven times its full load current

D. it will pick-up very high speed and may go out of step

6755. Slip ring motor is preferred over squirrel cage induction motor where___________?
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A. heavy pull out torque is required

B. load torque is heavy

C. high starting torque is required

D. all of the above

6756. In a star-delta starter of an induction motor___________?
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A. applied voltage perl stator phase is 57.7% of the line voltage

B. resistance is inserted in the stator

C. resistance is inserted in the rotor

D. reduced voltage is applied to the stator

6757. The crawling in an induction motor is caused by___________?
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A. improper design of machine

B. high loads

C. harmonics developed in the motor

D. low voltage supply

6758. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will____________?
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A. stall after sometime

B. continue to run at lower speed without damage

C. get heated and subsequently get damaged

D. stall immediately

6759. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be___________?
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A. Ns

B. (l-s)Ns

C. (Ns-l)s

D. s.N,

6760. In three-phase induction motors sometimes copper bars are placed deep in the rotor to___________?
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A. improve starting torque

B. reduce copper losses

C. improve power factor

D. improve efficiency

6761. The crawling in the induction motor is caused by____________?
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A. high loads

B. improper design of the machine

C. none of the above

D. harmonics develped in the motor

E. low voltage supply

6762. In induction motor, percentage slip depends on__________?
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A. supply frequency

B. supply voltage

C. none of the above

D. copper losses in motor
6763. The number of slip rings on a squirrel cage induction motor is usually____________?
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A. four

B. three

C. two

D. none
6764. Insertion of resistance in the stator of an induction motor___________?
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A. increases the starting torque

B. none of the above

C. increases the load torque

D. decreases the starting torque
6765. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type__________?
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A. A. and B. both

B. none of the above

C. delta connected only

D. star connected only

6766. In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?
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A. none of the above

B. to ensure easy fabrication

C. to reduce the magnetic hum and locking tendency of the rotor

D. to increase the tensile strength of the rotor bars

6767. In case of the induction motors the torque is___________?
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A. inversely proportional to slip

B. directly proportional to slip

C. inversely proportional to (Vslip)

D. directly proportional to (slip)2

6768. When the equivalent circuit diagram of doouble squirrel-cage induction motor is constructed the two cages can be considered__________?
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A. in parallel with stator

B. in series

C. in parallel

D. in series-parallel

6769. The torque developed in the cage induction motor with autostarter is___________?
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A. K2 x torque with direct switching

B. k2/torque with direct switching

C. K x torque with direct switching

D. k/torque with direct switching

6770. In an induction motor the relationship between stator slots and rotor slots is that_____________?
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A. none of the above

B. stator slots are not exact multiple of rotor slots

C. stator slots are exact multiple of rotor slots

D. stator slots are equal to rotor slots

6771. Insertion of resistance in the rotor of an induction motor to develop a given torque?
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A. increases the rotor current

B. rotor current rernains same

C. rotor current becomes zero

D. decreases the rotor current

6772. Reduced voltage starter can be used with_____________?
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A. squirrel cage as well as slip ring induction motor

B. squirrel cage induction motor only but not with slip ring motor

C. slip ring motor only but not with squirrel cage induction motor

D. none of the above

6773. In a three-phase induction motor__________?
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A. power factor at starting in the same as that while running

B. power factor at starting is high as compared to that while running

C. power factor at starting is low as compared to that while running
6774. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be__________?
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A. 0.03

B. 0.02

C. 0.01

D. 0.04
6775. A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor_______________?
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A. will stop and carry heavy current causing permanent damage to its winding

B. will continue running burning its one phase

C. will continue running without any harm to the winding

D. will continue running burning its two phases

6776. In case of a double cage induction motor, the inner cage has__________?
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A. low inductance and low resistance

B. low inductance and high resistance

C. high inductance and high resistance

D. high inductance arid low resistance
6777. Blocked rotor test on induction motors is used to find out?
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A. all of the above

B. power factor on short circuit

C. leakage reactance

D. short-circuit current under rated voltage

6778. The rotor of an induction motor runs at__________?
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A. any of the above

B. above synchronous speed

C. synchronous speed

D. below synchronous speed
6779. The vafcie of transformation ratio of an induction motor can be found by__________?
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A. short-circuit test only

B. none of the above

C. stator resistance test

D. open-circuit test only

6780. Rotor rheostat control method of speed control is used for____________?
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A. squirrel-cage induction motors only

B. slip ring induction motors only

C. both A. and (b)

D. none of the above

6781. When /?2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running conditions will be_____________?
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A. sR2 = X2

B. R2 = s2X2

C. R2 = sX2

D. sR2X2 = 1

6782. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor______________?
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A. will continue running without any harm to the winding

B. will continue running burning its one phase

C. will continue running burning its two phase

D. will stop and carry heavy current causing permanent damage to its winding
6783. It is advisable to avoid line starting of induction motor and use starter because____________?
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A. it will pick up very high speed and may go out of step

B. starting torque is very high

C. motor takes five to seven times its full load current

D. it will run in reverse direction

6784. Slip rings are usually made of___________?
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A. phospor bronze

B. copper

C. carbon

D. aluminium

6785. In an induction motor if air-gap is increased__________?
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A. the power factor will be low

B. windage losses will be more

C. copper loss will reduce In an induction motor

D. bearing friction will reduce

6786. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
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A. 730 r.p.m.

B. 960 r.p.m.

C. 1440 r.p.m.

D. 2880 r.p.m.

6787. The shaft of an induction motor is made of_____________?
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A. carbon steel

B. cast iron

C. stainless steel

D. high speed steel

6788. Low voltage at motor terminals is due to____________?
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A. none of the above

B. inadequate motor wiring

C. any one of the above

D. poorely regulated power supply

6789. DOL starting of induction motors is usually restricted to_____________?
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A. variable speed motors

B. high speed motors

C. high horsepower motors

D. low horsepower motors
6790. For driving high inertia loads best type of induction motor suggested is_____________?
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A. slip ring type

B. none of the above

C. any of the above

D. squirrel cage type

6791. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as____________?
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A. crawling

B. cogging

C. humming

D. hunting

6792. Stepless speed control of induction motor is possible by which of the following methods ?
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A. e.m.f. injection in rotor eueuit

B. Changing the number of poles

C. None of the above

D. Cascade operation

6793. In a three-phase induction motor, the number of poles in the rotor winding is always__________?
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A. less than number of poles in stator

B. equal to number of poles in stator

C. zero

D. more than the number of poles in stator

6794. The low power factor of induction motor is due to___________?
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A. stator reactance

B. all of the above

C. rotor leakage reactance

D. the reactive lagging magnetizing current necessary to generate the magnetic flux

6795. A double squirrel-cage induction motor has______________?
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A. two parallel windings in stator

B. two parallel windings in rotor

C. two rotors moving in oppsite direction

D. two series windings in stator

6796. The power scale of circle diagram of an induction motor can be found from__________?
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A. stator resistance test

B. short-circuit test only

C. no-load test only

D. noue of the above

6797. The purpose of using short-circuit gear is___________?
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A. none of the above

B. to short circuit the rotor at slip rings

C. to short circuit the starting resistances in the starter

D. to short circuit the stator phase of motor to form star

6798. Slip of an induction motor is negative when_____________?
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A. rotor speed is more than the synchronous speed of the field and are in the same direction

B. rotor speed is less than the synchronous speed of the field and are in the same direction

C. magnetic field and rotor rotate in opposite direction

D. none of the above

6799. An induction motor is__________?
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A. self-starting with high torque

B. self-starting with zero torque

C. self-starting with low torque

D. non-self starting

6800. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be____________?
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A. 200 Hz

B. 0.2 Hz

C. 50 Hz

D. 2 Hz