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 3 only 1, 3 1, 2, 3 and 4 1, 2 and 3 3 only 1, 3 1, 2, 3 and 4 1, 2 and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following motor has negative speed regulation? Cumulative compound motors Series motor Shunt motor Differential compound motor Cumulative compound motors Series motor Shunt motor Differential compound motor ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If Pi and Pc represent core and full load copper loss respectively, the maximum KVA delivered to load corresponding to maximum efficiency is equal to rated KVA is (Pi/Pc)2 Pi/Pc √(Pi/Pc) Pc/Pi (Pi/Pc)2 Pi/Pc √(Pi/Pc) Pc/Pi ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 220 V DC machine has an armature resistance 1 Ω. If the full load current is 20 A, the difference of induced voltage between generator and motor is 60 V. 0 V. 40 V. 20 V. 60 V. 0 V. 40 V. 20 V. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the applied voltage of a certain transformer is increased by 50% and the frequency is reduced by 50%, the maximum flux density will (assuming that the magnetic circuit remains unsaturated) changes to three times the original value changes to 0.5 times the original value changes to 1.5 times the original value remain the same as the original changes to three times the original value changes to 0.5 times the original value changes to 1.5 times the original value remain the same as the original ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The shaft of induction motor may be unbalanced due to uneven air gap. overload. poor lubrication. overheating of winding. uneven air gap. overload. poor lubrication. overheating of winding. ANSWER DOWNLOAD EXAMIANS APP
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