Trip times.

[Spark123]

I take it they must say on the BS4293 time delay devices what the time delay is.

 

[securespark]

Not the one I'm looking at now.

How do you work it out??

 

[Spark123]

I dunno, what does it say on it?

 

[securespark]

Just the usual guff.

BS EN 61008, 100A/ 100mA S type.

But no time delay info.

Have you got one to hand?

 

[Spark123]

BS EN 61008 type S should trip within 130ms - 500ms.
I don't have any of these to hand

 

[securespark]

Sorry 123, I'm all muxed ip tonight. I meant 4293, not 61008....

 

[Spark123]

Nothing hidden on the side of it? I suppose it may be a case of asking the manufacturer, GN3 just gives it for a BS4293 as 50% to 100% rated time + 200ms

 

[securespark]

So is that what you do? Ask the manufacturer? Surely these things are variable?

 

[Spark123]

If all else fails, that is probably your only port of call. I was blissfully unaware BS4293 called their time delayed devices type S. I suppose you learn something new every day . I don't know if they are variable, does it have a selector screw or something on it?

 

[securespark]

So you've never tested a TD RCD built to 4293? I've only done 2 but they were well within normal range so didn't do any calculations.

They're not user adjustable, AFAIK.

But, as you know, a 30mA device may trip out at less than 30mA. In the same way, I guess the delay time can be variable from unit to unit. So I suppose you must take the figure from the company as read.

It's not as if you can measure the time delay, can you?

 

[Adam_151]

Mk at least quote 350ms - 500ms for their devices, I suspect this is what the relevant standard calls for (as opposed to just what the mk devices are capacble of) as they also quote the 300/40 figures for normal devices as well, when as we all know an rcd will go a lot faster than 300 IRL

This seems to fit with the 1/2 delay + 200ms ----> delay + 200ms rule assuming a delay of 200ms, curiously the 200ms doesn't seem to become 300ms looking at these figures

 

[JohnD]

I thought the time delay was 100mS added on to the usual trip time. Don't know if I imagined it...

If you pull one apart you find a delay circuit inside it on a little PCB, I imagine these can be manufactured to a much tighter tolerance than the BS calls for.

 

[securespark]

Rang Electrium today & Wylex told me that their 100mA S types have a TD of 500ms.

But that's not right surely?

That would make the trip time between 450 and 700ms......

 

[securespark]

The OSG says "between X & Y..."

Does that mean if the trip time is lower than X it fails??

 

[Spark123]

I suppose so, not that it would matter too much providing it discriminates with any other RCDs in the system.
I have never come across any of these in my line of work, all our stuff afaik is TN-S.