Single Phase Motors Part 2 ONLINE MCQ

Single Phase Motors Part 2

Single Phase Motors Part 2

Instructions: Click the answer button to see the correct answer.

1. Which of the following applications would need the smallest size of motor ?

1. Table fan
2. Domestic motor
3. Electric clock
4. Sewing machine.

Answer: c

2. All single phase ac motors are designed to operate usually on

1. 220 V only
2. 220 ± 0 V
3. 220V + 10V
4. 220 ± 10% volts.

Answer: d

3. All single phase ac motors are designed usually to operate on the frequency

1. 50. ± 5 Hz.
2. 50 ± 0.5 Hz
3. 50 ±1 Hz
4. 50 Hz

Answer: a

Single Phase Motors Part 2

4. When a dc series motor is connected to ac supply, it will

1. all of these
2. run on poor power factor
3. spark excessively
4. give poor efficiency

Answer: a

5. The torque-speed characteristic of a repulsion motor resembles that of which of the following dc motor ?

1. separately excited motor
2. shunt motor
3. series is motor
4. compound motor.

Answer: d

6. In a single phase capacitor motor the direction of rotation will be in the opposite direction to the original when

1. two capacitors of equal value are used
2. capacitor is replaced by a resistance
3. capacitor is replaced by an inductor.
4. electrolytic capacitor is replaced by paper capacitor

Answer: c

7. In a hysteresis motor, the position of shaded pole with respect to main pole determines

1. hysteresis loss
2. speed of motor
3. no load rpm.
4. direction of rotation

Answer: d

Single Phase Motors Part 2

8. In a shaded pole motor, the direction of rotation is from

1. shaded pole to main pole
2. main pole to shaded pole
3. none of these
4. depends on supply line polarity.

Answer: b

9 . In a shaded pole motor, shading coils are used to

1. produce rotating magnetic field
2. reduce friction losses
3. reduce windage losses
4. to protect against sparking.

Answer: a

10. In a shaded pole motor, the locked rotor current is

1. less than the full load current.
2. slightly more than the full load current
3. 10 times the full load current
4. 4 to 5 times the full load current

Answer: b

11. Shaded pole motors are not provided with

1. commutator
2. centrifugal switch
3. capacitor
4. all of these

Answer: d

Single Phase Motors Part 2

12. In a universal motor, normally the ratio of width of brush to the width of commutator segments is

1. 1:1
2. 1:2
3. 2:1
4. 4:1.

Answer: c

13. For a given output and speed, a universal motor as compared to 220 V, 50 Hz supply will require

1. high voltage at high frequency
2. less voltage at high frequency
3. less voltage at low frequency
4. high voltage at low frequency.

Answer: c

14. The rotor of which motor does not have winding on it ?

1. Universal motor
2. Reluctance motor
3. Hysteresis motor
4. Repulsion motor.

Answer: c

15. Which motor has unsymmetrical rotor ?

1. Shaded pole motor
2. Reluctance motor.
3. Split-phase motor
4. Universal motor

Answer: b

16. If a single phase motor runs slow, the probable case may be

1. low voltage
2. low frequency
3. overload
4. any of these

Answer: d

17. A single phase capacitor start motor will take starting current nearly

1. three times the full load current
2. same as full load current
3. twice the full load current
4. four the six times the full load current.

Answer: c

18. Which motor will make least noise ?

1. Hysteresis motor.
2. Capacitor motor
3. Shaded pole motor
4. Universal motor

Answer: a

19. If a single phase motor runs hot the probable cause cannot be

1. blown fuses
2. high voltage
3. low voltage.
4. shorted stator coils

Answer: a

20. A single phase capacitor run motor will have starting torque as

1. 1/2 of full load torque
2. 1 1/2 times full load torque
3. 2 times full load torque.
4. same as full load torque

Answer: b

Single Phase Motors Part 2