Grading Capacitors

[FernandoCFE]

Hello,

Could somebody send me information about the application of "Grading Capacitors" in power breakers?
This type of capacitors can be used to increase the switching capacity of the breaker.

Thanks in advance,
FernandoCFE

 

[scottf]

Grading capacitors are used to control the transient recover voltage, resulting from close in faults. The capacitance helps to "smooth" the transient, thus making it easier for the breaker to open.

Typically, breaker manufacturers will state that X amount of pico-farads are needed within X distance of the breaker to increase the switching capacity of the breaker to a higher level (versus that without capacitors).

Some breaker designs have grading capacitors built internal and others use external capacitors. The external capacitors can be purchased with the breaker are direct from TRV capacitor manufactures, which are typically the same companies that make capacitor voltage transformers, like Ritz or Trench.