# Why does Induction Motor has Poor Power Factor at No Load

Induction Motor when started at no load has very poor power factor in the range of 0.1 to 0.3. For understanding the effect of loading on the power factor of Induction Motor, we will consider three components of current flowing in an Induction Motor namely Magnetizing Current, Stator Loss Component of Current and Load Component of Current one by one.

### Magnetizing Current Im:

As Induction Motor is an electro-mechanical device, therefore it will draw current to set up magnetic flux in the air-gap which is called Magnetizing Current. This Magnetizing Current lags the Stator Voltage V1 by 90°.

### Stator Loss Component of Current:

Stator Loss Component of Current provides the Stator Iron as well as Copper Loss just like in a Transformer.

The purpose of Load Component of Current is to balance the Rotor mmf which is demagnetizing in nature. Thus due to Load Component of Current a constant flux is set up in the air-gap of Induction Motor.

At no load, the power taken by the Induction Motor will be just enough to meet the no load losses like Friction and Windage Loss. Thus Induction Motor takes very less current from the supply main. Refer the phasor diagram below.

As shown in the phasor, Stator current at no load is I0 while I2 is load component of current. Mind that Load component of current is taken just to meet the rotor inertia and no load losses. It is quite clear that at no load component of current is very low as compared to the magnetizing current. This is because Induction Motor needs to set up rotating magnetic flux in the air gap and as because the reluctance of air is more, the magnetizing current taken from the supply main will be more. If we add magnetizing current and load component of current vectorically then I = I0+I2 will be much lagging and the angle Ɵ2 made by the resultant current I will be in the range of 75° to 85°, and therefore the Power factor will be much low in the range of 0.1-0.3.