DC MOTORS QUIZ

In a D.C. generator, the iron losses mainly take place in

Commutator

Armature conductors

Yoke

Armature rotor

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The armature torque of the D.C. shunt motor is proportional to

field flux only

None of these

both (A) and (B)

armature current only

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In D.C. shunt motors as load is reduced

The speed will increase in proportion to reduction in load

The speed will remain almost/constant

The speed will reduce

The speed will increase abruptly

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The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is

8.85%

4.76%

6.77%

2.22%

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The back emf in a dc motor ______

Aids the applied voltage

Aids the armature current

None of the listed here

Opposes the applied voltage

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By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?

Stator

Frame

Shaft

Commutator

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Ward-Leonard control is basically a

Armature resistance control method

Field control method

Field divertor method

Voltage control method

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The running speed of a dc series motor is basically determined by

None of the listed here

Armature reaction

Field excitation

Load

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Which of the following losses are significantly reduced by laminating the core of a D.C. generator?

Windage losses

Eddy current losses

Copper losses

Hysteresis losses

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By putting controller resistance in series with the armature of a dc motor, we can obtain speeds

None of the listed here

Below the normal speed only

Above as well as below the normal speed

Above the normal speed only

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