Electrical Machines When a transformer is loaded, the secondary terminal voltage drops. That means power factor is lagging. leading. zero. unity. lagging. leading. zero. unity. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 4 pole DC generator rotates at 1500 rpm. How many times in a second, will the emf induced in each armature conductor changes its direction? 500. 750. 100. 200. 500. 750. 100. 200. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Two 3-phase AC generators are such that one has twice the linear dimensions of the other. The field windings of each are excited to give identical sinusoidal air-gap flux density waveform. Both have the same number of stator slots and identical winding patterns. The conductor/slot in a big generator is K times that of the smaller one. The value of K to get equal no load voltage at same frequency is 4. 1/4. 1/2. 8. 4. 1/4. 1/2. 8. 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%. 67.5% 82.5% 72.5% 78.5% 67.5% 82.5% 72.5% 78.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following motors has low ratings only? Capacitor run Capacitor start Resistance split phase Shaded pole Capacitor run Capacitor start Resistance split phase Shaded pole ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3- phase synchronous motor can operate over a wide range of power factors i.e. from lagging to leading power factor. This is achieved by changing the field excitation. changing the load. varying the applied voltage. varying the speed. changing the field excitation. changing the load. varying the applied voltage. varying the speed. ANSWER DOWNLOAD EXAMIANS APP
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