A three - phase, 120 kW, 2300 V, 50 Hz, 1000 RPM salient pole synchronous motor develops total power of 100 kW. Neglecting losses, calculate the gross torque developed.

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Question

This question was previously asked in

PGCIL DT Electrical 5 May 2023 Official Paper

Answer 1

Concept:

Power - Torque equation for the rotating machine is: P = T × ω

And \(\omega = \frac{{2\pi N}}{{60}}\)

Therefore, \(P = T \times \frac{{2\pi N}}{{60}}\)

Where,

P is power-developed

T is torque-developed

ω is the angular speed of the machine

N is the speed of the motor in rpm

Calculation:

Power = 120 kW

Total power developed, P = 100 kW

Speed, N = 1000 RPM

Voltage, V = 2300 V

Putting the value in Power - Torque equation

\(100 ~kW = T \times \frac{{2\pi \times 1000}}{{60}}\)

T = 955 Nm