Electrical Machines The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is 2, 4 1, 3 1, 4 2, 3 2, 4 1, 3 1, 4 2, 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To eliminate the 5th harmonic in the induced voltages their respective pitch factor angle should be 72° 36° 30° 18° 72° 36° 30° 18° ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which method is less recommendable for induction motor starting in the industries? Rotor resistance starting. Direct online starting. Stator resistance starting. Auto transformer starting. Rotor resistance starting. Direct online starting. Stator resistance starting. Auto transformer starting. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When excitation is increased (over excitation), the synchronous generator operates at lagging power factor. leading power factor. unity power factor. any of the above. lagging power factor. leading power factor. unity power factor. any of the above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The shaft of induction motor may be unbalanced due to uneven air gap. poor lubrication. overload. overheating of winding. uneven air gap. poor lubrication. overload. overheating of winding. ANSWER DOWNLOAD EXAMIANS APP
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