Industries Extension Officer Synchronous Motors MCQs

SYNCHRONOUS MOTORS

11.A three phase synchronous motor will have:
A.no slip rings
B. three slip rings
C. four slip rings
D. two slip rings

2.When a synchronous motor is running at synchronous speed, the
damper winding produces
A. damping torque
B. eddy current torque
C. torque aiding the developed torque. 

D. no torque

3. A motor which can conveniently be operated at lagging as well as leading power factors is the
A. squirrel cage induction motor. 

B. wound rotor induction motor
C. synchronous motor
D. DC shunt motor

5. The max'm speed of a synchronous motor in India is:
A. 1500 rpm. B. 1000 r.p.m C. 750 rpm. D.3000 rpm.
The rotor of a synchronous motor is excited with DC when the motor
A. is at standstill 

B. approaches synchronous speed
C. approaches half synchronous speed 

D. none of the above

6. KW rating of synchronous motor exciter is about ....% of the KVA rating of synchronous motor
A. 3
B.
SEC. 10
D. 15

7.
Synchronous speed of an induction motor is always:
A. equal to rotor speed
B. greater than rotor speed
C. twice the rotor speed
D. less than rotor speed

8.
Synchronous speed of an induction motor is 1000 rpm.
What will be the rotor speed, if slip is 3%
A. 30 rpm
B.300 rpm. C. 1700 rpm D.970 rpm

9Asynchronous motor, connected to an infinite bus is working at
leading p.f. It's excitation is
A. less than supply voltage Vs
B. equal to Vs
C.> Vs
D. none of these

10. Synchronizing power comes into play when the rotor speed is
A. equal to Synchronous speed Ns
C. SNs
D. either more