GATE 2016 EE (EE2) – Question 32

Electrical Machines · Operating principle of single-phase induction motors · 1 mark · Multiple choice

The direction of a single-phase capacitor-run induction motor is reversed by

interchanging AC supply terminals
interchanging capacitor terminals
interchanging auxiliary-winding terminals
interchanging both winding terminals

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Show answer and explanation

Correct answer: (C) interchanging auxiliary-winding terminals

Explanation

Rotation depends on the relative spatial polarity and phase relationship of the main and auxiliary winding fields. Reversing only one winding reverses the rotating field.

Interchanging the auxiliary-winding terminals achieves this. Reversing both windings, or simply reversing the AC supply to the complete motor, preserves their relative relationship; swapping a nonpolar capacitor's terminals does not reverse its phase effect. Thus **C**.

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