53.

54.

55.

56.

57.

58.

59.

075/23

As the load on the transformer is increased, the core losses

A) Decrease slightly

B) Increase slightly

C) Remain constant

D) May decrease or increase slightly depending upon the nature of load

‘Crawling’ in an induction motor is due to

A) Space harmonics produced by winding currents
B) Insufficient starting torque

C) Slip-ring rotor

D) Time harmonics in supply

In a three phase induction motor, torque and supply voltage are related as
8) 1०५४” 8) 701 C) To V2 0( ۷

A three phase slip-ring induction motor is wound for four poles in stator and six poles in
rotor. When a three phase balanced voltage source at 50 Hz is applied to the motor, it
will run at

A) 1500 rpm B) 1000 rpm C) 750 rpm D) Not run

A synchronous motor and an induction motor are connected to a common feeder line. To
operate the feeder line at unity power factor, the synchronous motor should be

A) Under-excited

B)

C) Normally-excited

D) Disconnected from the common terminal

Over-excited

Which of the following single phase motor has highest starting torque ?
A) Capacitor start motor B) Repulsion motor
C) Shaded pole motor D) Split-phase motor

In an AC servomotor, the control winding is supplied with input voltage of

A) Any frequency compared to the reference winding but of the same phase

B) Any frequency compared to the reference winding but with 90° phase difference
C) Same frequency as the reference winding voltage and also having same phase
D) Same frequency as the reference winding voltage but with 90° phase difference

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