Electrical Machines If the excitation is critical, the power factor of the alternator is unity power factor. None of these leading power factor. lagging power factor. unity power factor. None of these leading power factor. lagging power factor. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A smaller air gap in a induction motor helps to increase the starting torque. reduce the magnetizing current. reduce the chance of cogging. reduce the chance of crawling. increase the starting torque. reduce the magnetizing current. reduce the chance of cogging. reduce the chance of crawling. 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 2, 3, 6 1, 2, 5 3, 4, 5 2, 4, 5, 6 2, 3, 6 1, 2, 5 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 82.5% 72.5% 67.5% 78.5% 82.5% 72.5% 67.5% 78.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When applied rated voltage per phase is reduce to one half, the starting torque of three phase squirrel cage induction motor becomes 1/4 of the intial value 1/2 of the initial value 4 time the initial value twice the initial value 1/4 of the intial value 1/2 of the initial value 4 time the initial value twice the initial value ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In which of the following generators negative voltage regulation can occur? both B and C over compound generator series generators shunt generator both B and C over compound generator series generators shunt generator ANSWER DOWNLOAD EXAMIANS APP
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