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Why a single-phase induction motor not an inherently
self-starting machine?

Answer Posted / raghav mishra

Single phase motor needs different method to start and run. The single phase line itself will not produce rotating field in stator because of only one sinusoidal not three like three phase supply. To create the rotating field, we must split the phase into two different sinusoidal wave that lagged for some degree each other. There are two method that commonly in used;
1. Use smaller diameter of winding wire in starting winding, so the current will flow faster compare to Running Winding.
2. Use of capacitor in starting winding- capacitor fast charge and discharge action makes the current leading.

When the supply is applied, the current in starting winding will lead the current in running winding hence we have rotating field that will induced emf in rotor. So the push pull action will began immediately.The Rotor turns and started.

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