For a single phase, 50 Hz transformer, if the open circuit test is conducted at 40 Hz. What is the variation in the no-load power factor of the transformer?(a) Decreases(b) Increases(c) Remains constant(d) None of the mentionedI had been asked this question during an online exam.I want to ask this question from Machine Ratings topic in chapter Rating and Loss Dissipation of Electrical Machines

For a single phase, 50 Hz transformer, if the open circuit test is con

1.	For a single phase, 50 Hz transformer, if the open circuit test is conducted at 40 Hz. What is the variation in the no-load power factor of the transformer?(a) Decreases(b) Increases(c) Remains constant(d) None of the mentionedI had been asked this question during an online exam.I want to ask this question from Machine Ratings topic in chapter Rating and Loss Dissipation of Electrical Machines
Answer» Correct answer is (a) Decreases Best explanation: If the frequency reduces then FLUX density INCREASES, so the flux and then the MAGNETIZING current. When magnetizing current increases power factor angle increases so the power factor decreases.

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