1. The ratio of starting torque to running torque in a synchronous motor is ?

zero

one

two

infinity

Answer: zero

Explanation:


2. In a synchronous motor, the maximum power developed depends on all of the following except ?

rotor excitation

maximum value of coupling angle

direction of rotation

supply voltage

Answer: direction of rotation

Explanation:


3. Change of D.C. excitation of a synchronous motor changes ?

applied voltage of the motor

motor speed

power factor of power drawn by the motor

any of the above

Answer: any of the above

Explanation:


4. Synchroning power of a synchronous machine is ?

directly proportional to the synchronous reactance

inversely proportional to the synchronous reactance

equal to the synchronous reactance

none of the above

Answer: inversely proportional to the synchronous reactance

Explanation:


5. The percentage slip in case of a synchronous motor is ?

1%

100%

0.5%

zero

Answer: zero

Explanation:


6. Synchronous motor always runs at ?

the synchronous speed

less than synchronous speed

more than synchronous speed

none of the above

Answer: the synchronous speed

Explanation:


7. Power factor of a synchronous motor is unity when ?

the armature current is maximum

the armature current is minimum

the armature current is zero

none of the above

Answer: the armature current is minimum

Explanation:


8. The net armature voltage of a synchronous motor is equal to the ?

vector sum of Eb and V

arithmetic sum of Eb and V

arithmetic difference of Eb and V

vector difference of Eb and V

Answer: vector difference of Eb and V

Explanation:


9. The percentage slip in case of a synchronous motor is ?

1%

100%

0.5%

zero

Answer: zero

Explanation:


10. Synchronous motor always runs at ?

the synchronous speed

less than synchronous speed

more than synchronous speed

none of the above

Answer: the synchronous speed

Explanation: