With V/F ratio keeping constant, if the frequency is decreased below the base value and the voltage is decreased proportionally, is fed to an Induction motor, its starting torque and the peak torque for variable frequency & voltages will be
- A. both starting torque and peak torque will remain constant
- B. Starting torque will increase and the peak torque remains constant
- C. starting torque will remain constant and peak torque will vary and the
- D. both starting torque and peak torque will decrease
Answer: B. Starting torque will increase and the peak torque remains constant
Explanation: With constant V/f ratio, the maximum (breakdown) torque remains constant, while the starting torque is inversely proportional to supply frequency (Tst ∝ 1/f); hence starting torque increases as frequency decreases.