Question 1

If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 6 
A) 2 
B) 3 
C) 4 
D) 6

Question 2

Under which of the following conditions hunting of synchronous motor is likely to occur ?

Accepted Answer

A) Periodic variation of load 
B) Over-excitation 
C) Over-loading for long periods 
D) Small and constant load 
A) Periodic variation of load 
B) Over-excitation 
C) Over-loading for long periods 
D) Small and constant load

Question 3

The minimum armature current of the synchronous motor corresponds to operation at

Accepted Answer

A) zero power factor leading 
B) unity power factor 
C) 0.707 power factor lagging 
D) 0.707 power factor leading 
A) zero power factor leading 
B) unity power factor 
C) 0.707 power factor lagging 
D) 0.707 power factor leading

Question 4

A three-phase synchronous motor will have

Accepted Answer

A) no slip-rings 
B) one slip-ring 
C) two slip-rings 
D) three slip-rings 
A) no slip-rings 
B) one slip-ring 
C) two slip-rings 
D) three slip-rings

Question 5

The synchronous motor is not inherently self-starting because

Accepted Answer

A) the force required to accelerate the rotor to the synchronous speed in an instant is absent 
B) the starting device to accelerate the rotor to near synchronous speed is absent 
C) a rotating magnetic field does not have enough poles 
D) the rotating magnetic field is produced by only 50 Hz frequency currents 
A) the force required to accelerate the rotor to the synchronous speed in an instant is absent 
B) the starting device to accelerate the rotor to near synchronous speed is absent 
C) a rotating magnetic field does not have enough poles 
D) the rotating magnetic field is produced by only 50 Hz frequency currents

If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is

Under which of the following conditions hunting of synchronous motor is likely to occur ?

The minimum armature current of the synchronous motor corresponds to operation at

A three-phase synchronous motor will have

The synchronous motor is not inherently self-starting because

Synchronous Motor: Part B

Synchronous Motors and Their Operation

Synchronous Motor Characteristics and Applications

Synchronous Motor: Power Factor, Back EMF, Torque, Losses

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Exam 1: Synchronous Motors: Part A

If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is

Under which of the following conditions hunting of synchronous motor is likely to occur ?

The minimum armature current of the synchronous motor corresponds to operation at

A three-phase synchronous motor will have

The synchronous motor is not inherently self-starting because

Synchronous Motor: Part B

Synchronous Motors and Their Operation

Synchronous Motor Characteristics and Applications

Synchronous Motor: Power Factor, Back EMF, Torque, Losses

Filters