Practice Test: Question Set - 07
1. A synchronous motor will always stop when
- (A) Supply voltage fluctuates
- (B) Load in motor varies
- (C) Excitation winding gets disconnected
- (D) Supply voltage frequency changes
2. To limit the operating temperature an electrical machine should have proper
- (A) Voltage rating
- (B) Current rating
- (C) Power factor
- (D) Speed
3. While starting a synchronous motor by induction motor action, field winding is usually
- (A) Connected to D.C. supply
- (B) Short-circuited by low resistance
- (C) Kept open-circuited
- (D) None of the above
4. The speed of a synchronous motor
- (A) Increases as the load increases
- (B) Decreases as the load decreases
- (C) Always remains constant
- (D) None of the above
5. The magnitude of field flux in a 3 phase synchronous motor
- (A) Remains constant at all loads
- (B) Varies with speed
- (C) Varies with the load
- (D) Varies with power factor
6. The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as
- (A) Slip torque
- (B) Pullout torque
- (C) Breaking torque
- (D) Synchronizing torque
7. The armature current of the synchronous motor
- (A) Has large values for low excitation only
- (B) Has large values for high excitation only
- (C) Has large values for low and high excitation
- (D) Any of the above
8. A synchronous motor can develop synchronous torque
- (A) When under loaded
- (B) While overexcited
- (C) Only at synchronous speed
- (D) Below or above synchronous speed
9. In a synchronous motor, the magnitude of stator back e.m.f. depends on
- (A) D.C. excitation only
- (B) Speed of the motor
- (C) Load on the motor
- (D) Both the speed and rotor flux
10. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor
- (A) Remains same as the original value
- (B) Decreases to half the original value
- (C) Tends to becomes zero
- (D) Increases to two times the original value
0 blogger:
Post a Comment