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GATE 2019 EE – Question 21

Electrical Machines · Synchronous machines: cylindrical and salient pole machines, performance and characteristics, regulation and parallel operation of generators, starting of synchronous motors · 1 mark · Multiple choice

A three-phase synchronous motor draws 200 A from the line at unity power factor at rated load. Considering the same line voltage and load, the line current at a power factor of 0.5 leading is

  1. 100 A
  2. 200 A
  3. 300 A
  4. 400 A

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Correct answer: (D) 400 A

Explanation

The real power is fixed, so $I\cos\phi$ is constant: $200\times1=I\times0.5$, giving $I=400$ A.