For controlling the speed of an induction motor the frequency of supply is increased by 10%. For magnetizing current to remain the same, the supply voltage must
- A. Be reduced by 10%
- B. Remain constant
- C. Be increased by 10%
- D. Be reduced or increased by 20%
Answer: C. Be increased by 10%
Explanation: Keeping flux (V/f) constant requires voltage to rise 10 % with a 10 % frequency rise.