Question

A 6 pole, 3-phase induction motor runs at a speed of 960 rpm with an input power of 40 kW. The stator copper loss at this operating conditions is 2 kW while rotational losses are 400 W. The electromagnetic torque developed is ______N-m.

• A. 362.87

Answer 1

The correct option is A 362.87
$\text{Electrical power input = 40 kW}$

$\text{Stator copper loss = 2.0 kW}$

$\text{Power across air gap = 38 kW}$

$\text{Synchronous speed,}$

$N_s=\frac{120\times 50}{6}=1000rpm$


${\omega }_s=\frac{2\pi \times N_s}{60}$

${\omega }_s=\frac{2\pi \times 1000}{60}=104.72rad/sec.$

$T_{ns}=\frac{P_{ag}}{{\omega }_s}=\frac{38\times {10}^3}{104.72}=362.87Nm$