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MCQs 1: A synchronous motor can develop synchronous torque:

when under loaded while over-excited only at synchronous speed below or above synchronous speed
Answer Explanation

MCQs 2: The maximum power developed in a synchronous motor will depend on__________?

the rotor excitation only the supply voltage only the rotor excitation and supply volt-age both the rotor excitation, supply voltage and maximum value of coupling angle (90°) none of the above
Answer Explanation

MCQs 3: In a synchronous motor, the breakdown torque is__________?

directly proportional to the square of the applied voltage directly proportional to applied voltage inversely proportional to applied voltage none of the above
Answer Explanation

MCQs 4: A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as_________?

static condenser condenser synchronous condenser none of the above
Answer Explanation

MCQs 5: If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then_____________?

the stator current will be zero the stator current will be very small the stator current will be very high the back e.m.f. will be more than the supply voltage none of the above
Answer Explanation

MCQs 6: The coupling angle or load angle of synchronous motor is defined as the angle between the__________?

rotor and stator teeth rotor and the stator poles of opposite polarity rotor and the stator poles of the same polarity none of the above
Answer Explanation

MCQs 7: The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as__________?

locked-rotor torque synchronous torque pull up torque reluctance torque
Answer Explanation

MCQs 8: If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will__________?

stop run as induction motor function as static condenser burn with dense smoke
Answer Explanation

MCQs 9: A synchronous machine with low value of short-circuit ratio has___________?

lower stability limit high stability limit good speed regulation good voltage regulation none of the above
Answer Explanation

MCQs 10: The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as___________?

pull-up torque pull-in torque pull-out torque none of the above
Answer Explanation

MCQs 11: The construction of a synchronous motor resembles____________?

a series motor an induction motor an alternator a rotary converter
Answer Explanation

MCQs 12: For power factor correction, synchronous motors operate at____________?

no-load and greatly over-excited fields no-load and under-excited fields normal load with minimum excitation normal load with zero excitation
Answer Explanation

MCQs 13: Which of the following losses is not dissipated by the stator core surface in a synchronous motor?

Eddy current losses in the conductors Iron losses in the stator Copper losses in the slot portion of the conductors Windage losses None of the above
Answer Explanation

MCQs 14: The size of a synchronous motor decreases with the increase in___________?

flux density horse power rating speed all of the above
Answer Explanation

MCQs 15: Which of the following losses, in a synchronous motor, does not vary with load?

Windage loss Copper losses Any of the above None of the above
Answer Explanation

MCQs 16: In a synchronous motor, the armature current has large values for____________?

high excitation only low excitation only both high and low excitation none of the above
Answer Explanation

MCQs 17: The back e.m.f. in the stator of a synchronous motor depends on____________?

number of poles flux density rotor speed rotor excitation none of the above
Answer Explanation

MCQs 18: If the field of a synchronous motor is underexcited, the power factor will be_____________?

zero unity lagging leading
Answer Explanation

MCQs 19: In a synchronous motor, the damping winding is generally used to______________?

reduce noise level reduce the eddy currents provide starting torque only prevent hunting and provide the starting torque none of the above
Answer Explanation

MCQs 20: In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then

the motor is said to be fully loaded the torque generated is maximum the excitation is said to be zero per cent the excitation is said to be hundred per cent
Answer Explanation

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