DC MOTORS QUIZ

The back emf in a dc motor ______

Aids the applied voltage

None of the listed here

Aids the armature current

Opposes the applied voltage

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In D.C. motor which of the following can sustain the maximum temperature rise?

Slip rings

Armature winding

Commutator

Field winding

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For starting a dc motor a starter is required because

It limits the speed of the motor

It limits the starting current to a safe value

It starts the motor

None of the listed here

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The friction and windage losses in a dc motor depends upon

Armature current

Field and armature resistance

Flux

Speed

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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

4.76%

8.85%

6.77%

2.22%

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A dc motor can be easily identified by

Commutator

Yoke

Winding

Size of conductor

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Small dc motors up to 5 HP usually have

8 poles

6 poles

2 poles

4 poles

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If a dc motor is to be selected for conveyors, which motor would be preferred?

Cummulative compound motor

Differentially compound motor

Shunt motor

Series motor

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At the instant of starting when a D.C. motor is put on supply, it behaves like

A capacitive circuit

None of these

A highly resistive circuit

A low resistance circuit

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In a dc compound machine,

Both play equally dominant role

Shunt field winding plays dominant role

Either can play dominant role

Series field winding plays dominant role

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