DGVCL Exam Paper (11-12-2011)
Which of the following correctly represents the sequence of operations of isolator, circiut breaker and earthing switch while opening a circuit?

Close circuit breaker-close isolator - open earthing switch
Close earthing switch - open ciruit- breaker-open islotor
Open isolator close circuit breaker-open earthing switch
Open circuit breaker-open isolator-close earthing switch

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DGVCL Exam Paper (11-12-2011)
The purpose of embedding the damper winding in the pole face of a synchronous motor is to

Reduce bearing friction
Eliminate losses on account of fair friction
Reduce winding losses
Eliminate hunting and provide adequate starting torque

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DGVCL Exam Paper (11-12-2011)
The purpose of interpoles in DC machines is to nullify

The reactance voltage
The cross-magnetizing effect of armature mmf
The demagnetizing effect of armature mmf
Both the cross-magnetizing mmf and the reactance voltage

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