Power Factor

Created On: 23-01-2015 Updated On: 25-03-2022

Power Factor

Typical inductive loads like electrical motors, lighting etc. require two kinds of powers i.e. active power (to perform the work) and reactive power (to create Electro-magnetic field). The vector sum of active and reactive power makes up the total power used. The total power is measured in KVA (Kilo Volt Ampere). The active power is measured in kW.

The ratio of KW to KVA is called power factor (cosØ), which is always less than or equal to unity.


CosØ = -------


Closer the CosØ to unity, less reactive power is drawn from the supply. A power factor less than unity results in increasing reactive energy consumption.

Capacitors are most commonly used to generate reactive energy and to maintain Power Factor near unity in electrical network.

Benefits of Good Power Factor   

  • Total current in the system from source end reduces due to reduction in reactive power component.
  • I2R power losses reduces due to reduction in current.
  • Voltage level at the load end is increased.
  • Better voltage at motor terminals improves performance of motor.
  • Saving can be achieved in electricity bills by lowering KVA demand.
  • Elimination of penalties in electricity bills due to low power factor.
  • Reduction in distribution losses.