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A 230 V, 50 Hz, 4-pole, single-phase induction motor is rotating in the clockwise (forward) direction at a speed of 1425 -rpm. If the rotor resistance at standstill is 7.8 Ω. then the effective rotor resistance in the backward branch of the equivalent circuit will be
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- 2 Ω
- 4 Ω
- 78 Ω
- 156 Ω
Correct Option: B
Synchronous speed,
| Ns = | = | = 1500 rpm | ||
| P | 4 |
| ∴ Slip , s = | = 0.05 | |
| 1500 |
∴ Resistance of backward branch,
| rb = | = | = 4 Ω | ||
| 2 - s | 2 - 0.05 |
