Single Phase Induction Motors

61. The electric motor used in portable drills is

1. capacitor run motor
2. hysteresis motor
3. universal motor
4. repulsion motor

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62. The motor used for the compressors is

1. d.c. series motor
2. shaded pole motor
3. capacitor-start capacitor-run motor
4. reluctance motor

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63. The motor used on small lathes is usually

1. universal motor
2. D.C. shunt motor
3. single-phase capacitor run motor
4. 3-phase synchronous motor

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64. The power factor of a single-phase induction motor is usually

1. lagging
2. always leading
3. unity
4. unity to 0.8 leading

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65. The purpose of stator winding in the compensated repulsion motor is to

1. provide mechanical balance
2. improve power factor and provide better speed regulation
3. prevent hunting in the motor
4. eliminate armature reaction

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66. The range of efficiency for shaded pole motors is

1. 95% to 99%
2. 80% to 90%
3. 50% to 75%
4. 5% to 35%

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67. The repulsion-start induction-run motor is used because of

1. good power factor
2. high efficiency
3. minimum cost
4. high starting torque

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68. The rotor developed by a single-phase motor at starting is

1. more than i.he rated torque
2. rated torque
3. less than the rated torque
4. zero

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69. The rotor of a hysteresis motor is made of

1. aluminium
2. cast iron
3. chrome steel
4. copper

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70. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it

1. improves the efficiency
2. helps the rotor teeth to remain under the stator teeth
3. helps in reducing the tendency of the rotor teeth to remain under the stator teeth
4. improves the power factor

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