Electric Drives (3160919) MCQs
MCQs of DC motor characteristics
| 61. |
The greatest percentage of power loss in a d.c. motor is due to ______________
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Answer:
Option (b) |
| 62. |
A motor takes a large current at starting because
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Answer:
Option (c) |
| 63. |
A DC shunt motor is running at 1200 RPM when excited with 220 V dc. Neglecting the losses and voltage dropped of the motor when connected to a 175 V supply is:
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Answer:
Option (d) |
| 64. |
A 240v dc shunt motor with an armature resistance of 0.5 has a full load current of 40A. Find out the ratio of the stalling torque to the full load torque when a resistance of 1 ohm is connected in series with the armature
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Answer:
Option (c) |
| 65. |
If the applied voltage of a DC motor is 230 V, then back emf, for maximum power developed is
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Answer:
Option (d) |
| 66. |
A DC Motor is driving a constant load torque having armature resistance of 0.15 Ω and armature current of 0.25 A having connected to a voltage of 230 V. Now a resistance of 1 ohm is added into the armature circuit. The ratio of their speed will be
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Answer:
Option (d) |
| 67. |
A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 Ω and the field winding resistance is 80 Ω. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is
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Answer:
Option (b) |
| 68. |
The basic elements of a electric drive are
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Answer:
Option (c) |
| 69. |
Speed control by variation of field flux results in
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Answer:
Option (a) |
| 70. |
Which of the following drive is used for metal-cutting machines tools, rolling mills etc
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Answer:
Option (c) |
