How to improve power factor?

To improve the power factor for a given load, the reactive load component (kvar) must be reduced.

This component of reactive power lags the power component (kW input) by 90 electrical degrees, so that one way to reduce the effect of this component is to introduce a reactive power component that leads the power component by 90 electrical degrees.

Several methods are used to improve the power factor in a system installation. One method that can be employed in large systems is to use synchronous motors to drive low-speed loads that require continuous operation.

A typical application for a synchronous motor is driving a low-speed air compressor, which provides process compressed air for the plant.

The synchronous motor is adjusted to operate at a leading power factor and thus provide leading kilovars to offset the lagging kilovar of inductive-type loads such as induction motors.

Synchronous motors are usually designed to operate at an 80% leading power factor and to draw current that leads the line voltage rather than lags it, as is the case with induction motors and transformers.