GATE 2020 EE – Question 56
A cylindrical rotor synchronous generator with constant real power output and constant terminal voltage is supplying 100 A current to a 0.9 lagging power factor load. An ideal reactor is now connected in parallel with the load, as a result of which the total lagging reactive power requirement of the load is twice the previous value while the real power remains unchanged. The armature current is now ________ A (rounded off to 2 decimal places).
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Show answer and explanation
Correct answer: 123.00 to 127.00
Explanation
With the terminal voltage fixed, currents are proportional to apparent power. The original load has $P=0.9$ and $Q=0.436$ per 100 A. Doubling $Q$ gives $Q=0.872$, so $I=100\sqrt{0.9^2+0.872^2}=125.3$ A.