DC MOTORS QUIZ

Compensating winding in a dc machine is placed

On yoke in the interpolar gap

None of the listed here

On yoke in the pole faces

On armature

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YOUR ANSWER : ?

In D.C. machines the residual magnetism is of the order of

20 to 25 percent

50 to 75 percent

10 to 15 percent

2 to 3 percent

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For a D.C. shunt motor if the excitation is changed

Torque will remain constant

Torque and power both will change

Torque will change but power will remain constant

Torque, power and speed, all will change

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The speed of a _____ motor is practically constant.

Differentially compounded

Shunt

Cumulatively compounded

Series

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For constant torque drive which speed control method is preferred?

Mechanical loading system

Field control

Armature voltage control

Shunt armature control

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If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking

None of these

Regenerative

Plugging

Dynamic braking

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The resistance of shunt field winding as compared to series field winding is

More

The same

None of the listed here

Less

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What will happen if the back emf of a dc motor vanishes suddenly?

The motor will run noisy

The motor will stop

The armature may burn

The motor will continue to run

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Which method of braking is generally used in elevators?

Regenerative braking

Plugging

None of these

Rheostat braking

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Armature reaction in dc motor is increased

When the armature current increases

By interpoles

When the field current increases

When the armature current decreases

TRUE ANSWER : ?
YOUR ANSWER : ?

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