Electrical Machine MCQs

If the primary line voltage rating is 3.3 kV(Υ side) of a 25kVA, Υ-Δ transformer ( the per phase turns ration is 5:1), then the line current rating of the secondary side is

A 25 kVA,400V, Δ- connected, 3-phase, cylindrical rortor synchronous generator requires a field current of 5A to maintain the rated armature current under short- circuit condition. For the same field current, the open-circuit voltage is 360V. Neglecting the armature resistance and magnetic saturation, its voltage regulation, when the generator delivers the rated load at 0.8 pf leading, at rated terminal voltage is 

A 120V DC shunt motor takes 2A at no load.It takes &a on full load while running at 1200 rpm. The armature resistance is 0.8 Ω, and the shunt field resistance is 240Ω. The no-load speed, in rpm, is 

A star-connected0.3, 12.5 kW, 208V(line), 3-phase, 60 Hz squirrel cage induction motor has the following equivalent circuit parameters per phase referred to the stator: R₁ = 0.3Ω, R₂= 0.3Ω, X₁=0.41Ω , X₂=041Ω. Neglect shunt branch in the equivalent circuit. The starting current for this motor when connected to an 80V, 20Hz, 3-phase AC source is 

A 220v, 10kW,900 rpm separately excited DC motor has an armature resistance Ra = 0.02Ω. When the motor operates at rated speed and with rated terminal voltage, the electromagnetic torque developed by the motor is 70 Nm. Neglecting the rotational losses of the machine,the current drawn by the motor from the 220 V supply is