Industries Extension Officer Synchronous motor mcq part2

Industries Extension Officer Synchronous motor mcq part2

11. In a 3-phase synchronous motor
A. the speed of stator MMF is always more than that of rotor MMF
B. the speed of stator MMF is always less than that of rotor MMF.
The speed of stator MMF is synchronous speed while that of

rotor MMF is zero.
D. rotor and stator MMF are stationary with respect to each other

12. A salient pole synchronous motor is running at no load. Its field
current is switched off. The motor will
A. come to stop.
B. continue to run at synchronous speed
C. continue to run at a speed slightly more than the synchronous speed
D. continue to run at a speed slightly less than the synchronous speed

13. Asynchronous motor is called a synchronous capacitor, when it is:
A. under loaded
B. under excited
C. over excited
D. overload

14. The size of a synchronous motor is determined by the its..
A.KVA rating
B. kW rating
C. KVAR rating
D. none of the above

15. The synchronous speed for a 3 phase 6-pole induction motor is 1200
rpm. If the number of poles is now reduced to 4 with the frequency
remaining constant, the rotor speed with a slip of 5% will be.
A. 1690 rpm B.1750 rpm C. 1500 rpm D. 1710 rpm

16. The maximum power for a given excitation in a synchronous motor

is developed when the power angle is equal to
A.
B.45
C. 60
D.90

17. Asynchronous motor delivers reactive power when.....
A. over excited
B. under excited
C. normally excited
D. none of the above

18. In synchronous motor out of the following losses, which one will
have the highest proportion ?
A. stator copper losses
B. friction and windage losses
C. eddy current losses
D. iron losses

19. The capacity of a synchronous capacitor is generally in the range of
A. VAR B.MVAR C .KVAR D. none of the above

20.
The cost of leading power factor synchronous motor is. .. unity
power factor motors
B. more than
A. less than
C. about the same
D. none of the above