43. In case one phase of a three-phase synchronous motor is short-circuited, the motor will
A. not start
B. run at ? of synchronous speed
C. run with excessive vibrations
D. take less than the rated load

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44. A pony motor is basically a
A. small induction motor
B. D.C. series motor
C. D.C. shunt motor
D. double winding A.C./D.C. motor

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45. A synchronous motor can develop synchronous torque
A. when under loaded
B. while over-excited
C. only at synchronous speed
D. below or above synchronous speed

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46. A synchronous motor can be started by
A. pony motor
B. D.C. compound motor
C. providing damper winding
D. any of the above

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47. A three-phase synchronous motor will have
A. no slip-rings
B. one slip-ring
C. two slip-rings
D. three slip-rings

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48. Under which of the following conditions hunting of synchronous motor is likely to occur?
A. Periodic variation of load
B. Over-excitation
C. Over-loading for long periods
D. Small and constant load

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49. When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected
A. the motor stops
B. it runs as a reluctance motor at the same speed
C. it runs as a reluctance motor at a lower speed
D. none of the above

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