TT system scenario - Thoughts please ?

[malcolmsanford]

Agree Gooner but some sparks still test the RCD at X5 .

Just going over the OP again, I wonder if he as a high Ra value and the meter is detecting a +50V touch voltage.

 

[gooner1984]

Agree Gooner but some sparks still test the RCD at X5 .

Just going over the OP again, I wonder if he as a high Ra value and the meter is detecting a +50V touch voltage.

maybe, but he said, 5x wont trip in 40ms, but it wont. again not sure but is there a time for when 5x100ma will trip, as your not suppose to test 5x 100ma. again correct me if im wrong :shades_smile:

 

[malcolmsanford]

Didn't he say that it won't operate as it is just displaying 40mS not that he was expecting it to trip within that time.

The regs want it to trip between 40mS and 150mS on 5x, and between 130mS and 500mS for the 1x

If you look at Chris Kitcher book he gives you his take on it as to be the rating current plus 200mS so for your 100mA on X1, so the 100mA RCD it should be 100+200, making it trip at 300mS, which is well within the 500mS in the Regs.

I know popular testing on any RCD exceeding 30mA is that you just do the x1/2 and the x1 but the regs do in fact give you the expected readings for the x5 on these RCD and there is no reason not to do it if you wish.

 

[gooner1984]

Didn't he say that it won't operate as it is just displaying 40mS not that he was expecting it to trip within that time.

The regs want it to trip between 40mS and 150mS on 5x, and between 130mS and 500mS for the 1x

If you look at Chris Kitcher book he gives you his take on it as to be the rating current plus 200mS so for your 100mA on X1, so the 100mA RCD it should be 100+200, making it trip at 300mS, which is well within the 500mS in the Regs.

I know popular testing on any RCD exceeding 30mA is that you just do the x1/2 and the x1 but the regs do in fact give you the expected readings for the x5 on these RCD and there is no reason not to do it if you wish.

just had a quick flick through the chris kitcher book p109 in the green and yellow square it says "the 5 times test MUST only be carried out on RCDs with trip ratings up to 30ma.
thats what confusing me, :stuart:

 

[Richard Burns]

There are no references that I can find to ever testing an RCD with a rating >30mA at 5x its rated current.

100mA time delayed RCDs should be tested on positive and negative half cycles at both 0.5x and 1x rated current.
The RCD should trip in a time from 130ms to 500ms at 1x and should not trip at 0.5x.

 

[malcolmsanford]

just had a quick flick through the chris kitcher book p109 in the green and yellow square it says "the 5 times test MUST only be carried out on RCDs with trip ratings up to 30ma.
thats what confusing me, :stuart:

Sorry gooner it is John Whitfield's book and not Chris' that give you his take on things. I think it is also still on the Tender Loving Care website in their technical section.

Sorry mate all these guides blur into one after a while

 

[AA410]

Hi Thanks for all your reply i have a megger RCD tester the 100ma rcd trips at 25.4ms at 1x but will not trip a 5x my tester displayes 40ms and does not trip ?

 

[gooner1984]

Hi Thanks for all your reply i have a megger RCD tester the 100ma rcd trips at 25.4ms at 1x but will not trip a 5x my tester displayes 40ms and does not trip ?

again anything above 30ma. must not be tested at 5x so don't worry, it trips at 1x within the limits :crazy:

 

[malcolmsanford]

As all the other lads have said there is no need to test a 100mA at x5, not being a megger man, but could the megger be set up that once you select 100mA it over rides the x5 test?

Have you had success of testing any 100mA RCDs on the x5 with it?

If not it could be a faulty RCD.

 

[gooner1984]

and remember to test at both halfs of the cycle

 

[AA410]

Thanks again not had much to do with 100ma RCDs it will trip on both cycles on 1x if there is nothing to worry about its one of them thing that you like to understand why

 

[gooner1984]

Thanks again not had much to do with 100ma RCDs it will trip on both cycles on 1x if there is nothing to worry about its one of them thing that you like to understand why

because you don't have to do the test that's why you dont worry about it. upto 30ma its 0.5x 1x and then 5x and 100ma and above is 0.5x and 1x

 

[AA410]

Thanks good people great advice

 

[Engineer54]

There's a very good chance this 100mA S type RCD is faulty, if it's tripping at 25 mS!! As far as i remember it should be tripping at around 120 or 130 mS. There won't be any discrimination with any downstream 30mA RCD devices, it there is a fault at anywhere near 100mA... Any chance of checking your RCD tester against another RCD tester??

 

[i=p/u]

NEED A SPARK, CALL TODAY FOR NO DELAY. HOPE THIS HELPS values at Uo of 230v
BSEN 61008
BSEN 61009
≤ 300mS
( 0.3 s )
≤ 40mS
0.4S
BSEN 61008 delay S
BSEN 61009 delay S
130-500mS
(0.13 – 0.5s)
40-150mS
(0.04 – 0.15s)