Automatic Power Factor Controller (APFC)
Q. State the working principle and operation of automatic power factor controller used in transmission distribution system.
- In this case the capacitor bank is connected across the line for controlling power factor it is controlled through micro controller and contactor arrangement.
- On the basis of kVAR demand pf of the load is sensed and capacitors are connected disconnected.
- See the relation Real power =Apparent power X p.f. Thus maintaining the p.f. at unity results in reduction in current through the lines.
- The apparent power(i.e. kVA) decides the maximum demand (MD) for which the consumer is billed See the above block diagram of the controller
Equipments connected are AC power source capacitor bank voltage and current sensors contactor and capacitor switched and power measurement IC.
Action of APFC : A.C. supply mains are connected to the panel of “APFC’. In line sides the CT and PT are placed which senses P.F.
- Capacitor banks are operated as per requirements to get the calculated p.f. For this microprocessor-based APFC relay is used.
- The approximate capacitor bank operates with respect to KVAR required to get targeted p.f. by APFC panel.
- Then CT and PT check the feedback from switching capacitors.
- In this way, finally, required set p.f. is achieved.