Why is the power factor of a 3-phase induction motor low at no-toad?

Because of air-gap, the reluctance of the magnetic circuit of 3-phase induction motor is very high. Consequently, the current drawn by the motor on no load is largely magnetizing cur­rent; the no load current lagging the applied voltage by a large angle. For this reason, the p.f. of a lightly loaded 3-phase induction motor is very low.