Power factor is the ratio of average power to apparent power of AC circuit. Power Factor is related to the load nature of the circuit. For example, the power factor of resistance load such as incandescent bulb and resistance furnace is 1. Generally, the power factor of circuit with inductance load is less than 
1. Power factor is an important technical data of power system. Power factor is a coefficient to measure the efficiency of electrical equipment. The low power factor indicates that the reactive power of the circuit used for alternating magnetic field conversion is high, which reduces the utilization ratio of the equipment and increases the loss of power supply. In AC circuit, the cosine of phase difference (Φ) between voltage and current is called power factor, which is expressed by symbol cosΦ. In numerical value, power factor is the ratio of active power to apparent power, that is cosΦ=P/S.

Increasing power factor can save power capacity, reduce line losses and improve the utilization of power equipment. At present, shunt capacitor compensation is widely used in power factor artificial compensation.
 
Increasing power factor will certainly promote the energy utilization of the country and the economic benefits of enterprises. It is an indispensable condition for ensuring the power quality, voltage quality, reducing network loss and safe operation of power system. Corresponding measures should be taken to improve power factor and reduce reactive power loss according to different situations, so as to improve economic benefits.