RCD tripping time (in factory)

[Bradley6969]

Hi, bit confused, have an RCD Main Switch 250A with variable settings for mA and mS, now this is set at 1000mA, 1s time delay, I’m getting 99ms with set on 1000mA and no time delay my tester does not do 1s delay, now this board feeds another, so will I put 1099ms for tripping time?
I was just confused as I see max tripping time 500ms for a time delayed RCD somewhere could be wrong? It’s only a distribution circuit
Thanks

 

[Lucien Nunes]

I don't think you want to add the tested tripping time to the delay set on the dial. If the tester will not provide a 1 second test, you cannot show that the RCD trips correctly as set, so you cannot complete that test as such.

The maximum permissible delay setting depends on what protection it is providing. For a distribution circuit on a TT installation I believe 1s is the norm.

 

[davesparks]

So is the RCD tripping in 99mS? Or is it not tripping and the tester is showing >99mS as they often do to indicate that it has not tripped.

If it has tripped in 99mS then the delay isn't working.
If it has not tripped then you can't record any time for it because it hasn't operated.

You could adjust the time delay for the test so that it falls within the abilities of the tester, this will at least prove that the RCD works, but it won't prove what it does at its cirrect settings.