A 480 V, 60 Hz, three-phase induction motor has a rated speed at full load of 1720 rpm, stator resistance of 1 ?, rotor resistance of 1 ?, and equivalent winding reactance of 4 ?. Compute the starting time of the motor at no load and at full voltage and frequency. The inertia of the motor is 3 Nm sec2

What will be an ideal response?


Since the frequency is 60 Hz and the rated speed is 1720 rpm, the synchronous

speed must be 1800 rpm; hence the machine has 4 poles.

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