Application of Electromechanical Contactors for Power Factor Correction

Contactors for Power Factor Correction New capacitors place additional demands on contactors to keep power circuits balanced. Ind. Control Div., Eaton Corp. • Electrical power sources supply two types of power to inductive loads: real power in kW and reactive power in VAR. • Power-factor correction circuits can be either an individual style or of the bank/group style. • Banked or group PFCs are typically controlled with a VAR controller Most loads applied to modern electrical-distribution systems are inductive. Electric motors, transformers, and high-intensity discharge lighting make up a large portion of the power consumed in an industrial setting and all contribute to the inductive load. An inherent problem with inductive loads is that they lead to poor PFs that degrade overall system-operating efficiency. When applied correctly, power-factor-correction (PFC) systems can eliminate the negative effects of a poor PF. Readers will probably recall that inductive loads need two types of power: Working or real power, measured in kilowatts (kW), performs the actual work of creating heat, light, motion, and so forth. But inductive loads also need a second type of power known as reactive power, measured in kilovolt-Amps reactive (kVAR), to sustain the magnetic field inherent to inductive loads. When combined, working and reactive power form apparent power measured in kilovolt-Amps (kVA): the total power supplied to the system by the power source. The power factor (PF) of a circuit is the measure of electrical distribution efficiency. In simple terms, it is the ratio between the amount of real power used to perform actual work (kW) and the apparent power (kVA) supplied by the power source. For example, if the apparent power of a circuit was 200 kVA, but only 190 kW of actual work is done, then the PF is said to be 0.95 or 95%. Low PFs can lead