APFC stands for ‘automatic power factor correction’. An APFC panel consists of multiple capacitors of different ratings whose switching can be controlled as per requirement. An APFC is effective as a single-point installation which can be used to control the power factor for a large number of loads,
instead of installing capacitors at the individual locations of each load. Depending on the loads in operation, various levels of kVAR compensation are required to maintain proper power factor. The APFC panel contains a multi-step relay which is connected to multiple capacitors and a microprocessor controller which is programmed to control the switching operation of the relay. The voltage and current are measured on the feeder which is providing supply to the entire group of loads to determine the uncompensated power factor. Then, as per the ratings of the different capacitors used in the APFC and the measured uncompensated power factor, the controller determines which capacitors are to be switched on/off to achieve optimal power factor.