Electrical Machines A 230 V, 50 Hz, 4 pole single phase induction motor is rotating in the clockwise ( forward ) direction at a speed of 1425 rpm. If the rotor resistance at standstill is 7.8 Ω. Then the effective rotor resistance in the backward branch of the equivalent circuit will be 8 Ω. 4 Ω. 2 Ω. 10 Ω. 8 Ω. 4 Ω. 2 Ω. 10 Ω. 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%. 72.5% 82.5% 67.5% 78.5% 72.5% 82.5% 67.5% 78.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Torque angle of a synchorous machine operating from a constant voltage bus is usually defined as the space angle between Stator mmf wave and resultant mmf wave. Rotor mmf wave and stator mmf wave. Stator mmf wave and resultant flux density. Rotor mmf wave and resultant flux density wave. Stator mmf wave and resultant mmf wave. Rotor mmf wave and stator mmf wave. Stator mmf wave and resultant flux density. Rotor mmf wave and resultant flux density wave. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3-phase, 2 pole, 12 slot synchronous machine is operating at synchronous speed. Find the slot angle? 18° 60° 20° 30° 18° 60° 20° 30° ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Resistance commutation is used generally in case of DC machines bellow 5 kW. None of these DC machines above 10 kW. fractional kW DC machines. DC machines bellow 5 kW. None of these DC machines above 10 kW. fractional kW DC machines. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When excitation is increased (over excitation), the synchronous generator operates at unity power factor. leading power factor. lagging power factor. any of the above. unity power factor. leading power factor. lagging power factor. any of the above. ANSWER DOWNLOAD EXAMIANS APP
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