Surge Arrestor vs. Surge Suppressor, What's the difference?

[cjones09]

Can someone explain the difference between a surge suppressor and surge arrestor? I am trying to hipot a 29MCOV arrestor, should it short to ground at 29kV? I was able to take it to 35kV and got 2mA leakage. Didn't want to go any higher.

[ullahasgar]

You probably already figured out by now. Surge arrestors (in now times) are NON Linear metal oxide assemblies put together with Gaps to absorb any power system transient over voltage - for a certain amount of time - diverting the surge to ground (However still maintaining reference voltage to keep System shortcircuits for happening) thereby protecting the equipment.

Coming back to hipoting the SA. I dont advice hipoting SAs. MCOV stands for Maximum Continuous Operating Voltage. The analysis of the leakage current will reveal mostly capacitive current with very little resistive component. It is, in theory also designed to withstand a number called Rated Voltage which it will withstand for 10sec. in theory. I'd recomment DOble power factor test where the capacitive number can be compared with identical model SAs.

Let me know if any questions.

[alexlounsbury]

I'd second the above advice, there's no point in performing an AC Overpotential test on a surge arrestor. A bit higher and you would see current draw increase drastically, and quickly kick the test set off. I'd just perform a DC Insulation Resistance (Megger) test, and move on. If you wanted to do a more thorough test, you could perform a power factor as recommended.

For your title question, I think a Surge Arrestor is a dumb device designed to short to ground in a overvoltage condition. When I picture a Surge Suppressor, I think of a re-settable device with an alarm contact and a brain (processor) of some kind, possibly with a resistor between ground and the connection to limit fault current. Generally what you'd see on new 480V switchgear.