why induction motor having low power factor at starting time
and high at full load.

Answer Posted / sree

At the starting condition, the induction motor draws higher magnetisation component of current in order to overcome the reluctance offered by air gap between stator and rotor. Then the total current increases.  In the phasor representation, the angle between coreloss component and net current increases. As the power factor is the cos of angle between net current and core loss component, therefore the power factor decreases.

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