Capacitor Protection Relays - An Overview

Capacitors Protection Relays are dedicated relays which are designed to provide a range of protection functions for capacitors.

Capacitors are widely used in power systems for VAr regulation and PF control.  They are also used for filtering harmonics.  

Capacitor banks need to be protected against overload by harmonic currents. They also need to be protected against system overvoltages. 

Capacitor Protection Relays consist of a number of different protection elements such as overcurrent, overvoltage, differential protection, etc.    They also have protective interlocks such as preventing an energised capacitor from being connected to the network.