Electrical Machines
In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is

 maximum
 infinite value
 any of the above
 zero

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Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

 there was no residual magnetism in the field circuit
 there was a break in the armature circuit
 field resistance was higher than critical resistance
 field winding was wrongly connected

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Electrical Machines
In a dc generator operating on load with its brushes on the geometrical neutral axis (GNA), the magnetic neutral axis (MNA) is shifted in the direction of rotation. Now, if the brushes are given a lead of 90° (electrical), then the MNA will

 shift forward by less than 90°
 shift forward by 90°
 coincide with the GNA
 shift forward by more than 90°

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