ELECTRICIAN 2nd YEAR MODULE – Synchronous Motor and MG Set

Question 1 of 18

1. What is the purpose of damper winding in a synchronous motor at starting?

Produce a high magnetic-field to maintain a constant speed

Produces torque and runs near in synchronous speed

Produce high current to start rotate the motor

Produce high voltage to initiate the rotation

Question 1 of 18

Question 2 of 18

2. What is the function of inverter?

Convert A.C to D.C

Convert D.C to A.C

Convert pulsating DC into pure D.C

Smoothening A.C sine wave

Question 2 of 18

Question 3 of 18

3. Which converter is having high efficiency?

SCR converter

Motor generator set

Mercury arc rectifier

Rotary converter

Question 3 of 18

Question 4 of 18

4. Why D.C supply is necessary for synchronous motor operation?

Run the motor at synchronous speed

Reduce the losses

Start the motor initially

Run the motor with over load

Question 4 of 18

Question 5 of 18

5. Why the synchronous motor fails to run at synchronous speed?

Short in damper winding

Open in damper winding

Defective pony motor

Insufficient excitation

Question 5 of 18

Question 6 of 18

6. Why exciter is essential to run a synchronous motor?

Reduce the losses in motor

Carry more load in motor

Run the motor at synchronous speed

Improve the power factor

Question 6 of 18

Question 7 of 18

7. Which application requires only DC?

Electroplating

Operating induction motor

Operating repulsion motor

Stepping up of voltage

Question 7 of 18

Question 8 of 18

8. Which converting device can be over loaded?

Mercury arc rectifier

Rectifier unit

Motor generator set

Rotary converter

Question 8 of 18

Question 9 of 18

9. What is the advantage of motor generator set?

Noiseless

DC output voltage can be easily controlled

High efficiency

Low maintenance required

Question 9 of 18

Question 10 of 18

10. Which is the main application of synchronous motor?

AC to DC converter

Power factor correction device

Elevators

Paper rolling mills

Question 10 of 18

Question 11 of 18

11. How the synchronous motor is used as a synchronous condenser?

Varying stator current in motor

Varying the motor load

Varying the rotor excitation

Varying stator voltage in motor

Question 11 of 18

Question 12 of 18

12. Why the LED's are avoided as converters in rectifier diodes?

Very sensitive to temperature

Designed for light emitting

Very low power device

Heavily doped device

Question 12 of 18

Question 13 of 18

13. What is the function of the part marked as 'X' of the rotary converter?

Converts AC to DC

Reduces voltage drop

Helps to deliver without noise

Collects the delivered direct current

Question 13 of 18

Question 14 of 18

14. Which acts as both inverter and converter?

Mercury arc rectifier

Metal rectifier

Synchronous converter

Semi conductor diode

Question 14 of 18

Question 15 of 18

15. What is the function of damper windings in synchronous motor?

Maintain power factor

Maintain constant speed

Start the synchronous motor

Excite the field winding

Question 15 of 18

Question 16 of 18

16. What is the name of the converter?

Silicon controlled rectifier

Rotary converter

Metal rectifier

Mercury arc rectifier

Question 16 of 18

Question 17 of 18

17. What is the name of the converter?

Metal rectifier

Rotary converter

Mercury arc rectifier

Motor-Generator set

Question 17 of 18

Question 18 of 18

18. How synchronous motor works as a power factor corrector?

Varying the field excitation

Increasing the speed of motor

Decreasing the speed of motor

Varying the line voltage

Question 18 of 18