Page 721 - Basic Electrical Engineering

No-load power input = 300 W

Core loss + Frictional and Windage loss = 300 – 43.2
= 256.8 W

Output = 10 hp = 10 × 735.5 = 7355 W

Efficiency,

Example 8.13 A three-phase, 20-pole slip-ring induction motor runs at 291

rpm when connected to a 50 Hz supply. Calculate slip for full-load torque if
the total rotor-circuit resistance is doubled. Assume R >> SX .
2
2

Solution:

slip,

Full-load torque equation is,