A 3-phase induction motor is driving full-load torque which is independent of speed. If line voltage drops to 90% of the rated value, percentage increase in motor copper losses
- A. 23%
- B. -18%
- C. 123%
- D. 25%
Answer: A. 23%
Explanation: Constant torque with V = 0.9 gives I ∝ 1/0.9 = 1.111; copper loss ∝ I² = 1.235, i.e. about +23 %.