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A voltage source inverter is used to control the speed of a three-phase, 50 Hz, squirrel cage induction motor. Its slip for rated torque is 4%. The flux is maintained at rated value. If the stator resistance and rotational losses are neglected, then the frequency of the impressed voltage to obtain twice the rated torque at starting should be
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- 10 Hz
- 5 Hz
- 4 Hz
- 2 Hz
Correct Option: C
| T = | × | |||
| [R2 + (sn2)2] | 2 π Ns |
Trated ∝ s
| f2 = sf1 ⇒ s = | ||
| f1 |
In first case, f2 = 2Hz
For twice rated torque f2 will be twice, so f2 = 4 Hz.
