Power factor correction system is the process of adjusting the phase and magnitude of the voltage in an AC electrical power system so that the load current drawn by the system matches the supply current. The power factor is the ratio of the real power to the apparent power, and is a measure of how efficiently the system is using the available power. A power factor of 1.0 indicates that the system is using the power supplied to it perfectly, while a power factor of 0.5 indicates that only half of the power supplied to the system is being used.