Electrical Machines The speed of stator rotating magnetic field (RMF) with respect to rotor is Ns Zero S.Ns Nr Ns Zero S.Ns Nr ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following methods are used to control the speed of DC motors is armature circuit resistance control All of these supply voltage control field current control armature circuit resistance control All of these supply voltage control field current control ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In induction motor when the length of the air gap is increased, the magnetizing current of the motor increases while the short circuit current __________________. remains unchanged. kept constant to certain value. increased. decreased. remains unchanged. kept constant to certain value. increased. decreased. 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%. 78.5% 82.5% 67.5% 72.5% 78.5% 82.5% 67.5% 72.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the temperature of armature resistance is increased, the speed of a series motor would None of above. decrease. increase. not change. None of above. decrease. increase. not change. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For a 3-phase, 4 pole, 50 Hz synchronous motor the frequency, pole number and the frequency are halved. The motor speed will be 75 rpm 375 rpm 1500 rpm 3000 rpm 75 rpm 375 rpm 1500 rpm 3000 rpm ANSWER DOWNLOAD EXAMIANS APP
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