DC GENERATORS QUIZ

In a four-pole D.C. machine

All the four poles are north poles

All the four poles are south poles

Two north poles follow two south poles

Alternate poles are north and south

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The coupling field between electrical and mechanical systems of a dc machine is ______

Magnetic field

None of the listed here

Both electrical and magnetic fields

Electric field

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The yoke of a dc machine carries ______ pole flux.

None of the listed here

Three times

Two times the

One-half of

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In a D.C. generator the critical resistance refers to the resistance of

Brushes

Armature

Load

Field

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The field coil of dc generator are usually made of

Cast iron

Mica

Carbon

Copper

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The nature of armature winding of a dc machine is decided by

None of the listed here

Back pitch

Front pitch

Commutator pitch

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In D.C. generators the polarity of the interpoles

Is the same as that of the immediately preceding pole

Is opposite to that of the main pole ahead

Is neutral as these poles do not play part in generating e.m.f.

Is the same as that of the main pole ahead

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When two D.C. series generators are running in parallel, an equalizer bar is used

To reduce the combined effect of armature reaction of both machines

To increase the series flux

To increase the speed and hence generated e.m.f.

So that two similar machines will pass approximately equal currents to the load

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The efficiency of a dc generator means its

Mechanical efficiency

Overall efficiency

Electrical efficiency

None of the listed here

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A shunt generator gives its greatest voltage at

None of the listed here

No load

Half full load

Full load

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