GATE 2014 EE (EE2) – Question 24
A single-phase induction motor draws 12 MW at 0.6 lagging power factor. A parallel capacitor improves combined power factor to 0.8 lagging. Motor real and reactive powers remain unchanged. Find capacitor reactive power delivered (MVAr).
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Show answer and explanation
Correct answer: 6.97 to 7.03
Explanation
The motor real power remains12MW. Initially tanφ1=√(1−0.6²)/0.6=4/3,so Q1=16MVAr. At0.8power factor,tanφ2=0.6/0.8=0.75,so the combined Q2=9MVAr. The capacitor supplies their difference, **7MVAr**,while leaving real power unchanged.