Electrical Machines A large series motor is never started without some mechanical load on it because otherwise it will open fuse or circuit breaker. develop excessive speed and damage itself. produce sparking at brushes. draw too much current. open fuse or circuit breaker. develop excessive speed and damage itself. produce sparking at brushes. draw too much current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Unbalanced supply voltage given to a 3 - φ, delta connected induction motor will cause all of these. less heating of the rotor. negative sequence current. less heating of the rotor. all of these. less heating of the rotor. negative sequence current. less heating of the rotor. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The counter (or back) emf in a dc machine is 1. the same as generated emf in a dc motor 2. proportional to field flux and armature speed 3. not the same as generated emf in a dc motor 4.inversely proportional to field flux 5. proportional to number of armature conductors 6. constant from no load to full load From these, the correct answer is 2, 4, 5, 6 1, 2, 5 3, 4, 5 2, 3, 6 2, 4, 5, 6 1, 2, 5 3, 4, 5 2, 3, 6 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The material used for commutator brushes is mostly carbon. copper. cast iron. mica. carbon. copper. cast iron. mica. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Fufuraldehyde analysis is done to determine the condition of cork gaskets used in transformer. condition of lamination on CRGO steel sheet. condition of paper insulation in transformer. condition of oil in transformer. condition of cork gaskets used in transformer. condition of lamination on CRGO steel sheet. condition of paper insulation in transformer. condition of oil in transformer. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC generator sparking between brushes and commutator surface may be due to under commutation. too rapid reversal of current. over commutation. any of the above. under commutation. too rapid reversal of current. over commutation. any of the above. ANSWER DOWNLOAD EXAMIANS APP
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