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A 1,000 kW synchronous motor at 0.9 power factor leading supplies reactive power of about

  • A.1,111 kVAr
  • B.484 kVAr
  • C.900 kVAr
  • D.100 kVAr

Answer: B

Correct answer: 484 kVAr

The apparent power is

\[ S = \frac{P}{\cos\phi} = \frac{1000}{0.9} = 1111 \text{ kVA} \]

and with \( \sin\phi = \sqrt{1 - 0.81} = 0.436 \),

\[ Q = S\sin\phi = 1111 \times 0.436 \approx 484 \text{ kVAr} \]

Because the power factor is leading, that 484 kVAr is supplied to the network, offsetting the lagging demand of induction motors elsewhere in the plant.

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