Relay Response - RMS or Peak

[coloradog1]

Hello guys. I have some old ABB Circuit Shield and Ground Shield Relays. I was curious if anyone had an idea of whether they would respond to RMS or Peak current.

Thanks for the thoughts.

 

[jghrist]

Most microprocessor relays use a digital filter to extract the rms value of the fundamental component of the current. You should check with ABB about the particular relay. Certainly, the current values used in the TCC characteristics are rms, not peak.

 

[cranky108]

Some microprocessor relays will respond to asymmetrical current values, and not symmetrical values.
This can cause a problem if you use a symmetrical fault study program.