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Sorry what? So if it trips 350ms for example it’s 50ms?
If set at zero and when tested it trips at 1x in 50mS then you set the delay to 300mS then the tripping time would be 350mS.

Your test meter will see this as a fail and not test past 300mS unless you have the option to set a time delay on it.

If your trying to discriminate against 30mA RCDs then you need to take into account the 5x test time and set the upfront accordingly.
 
Which setting or are you on about both? It’s for some lodges so hence the upfront RCD as earthing is TT
The ma is the current needed to make it trip. The ms is the delay so if you set at 300ma with a 300ms delay the device will allow 300ma of fault to flow for up to 300ms before it trips.
 
Thanks I understand better now, so I’ll set to 300mA and test with no ms and see trip time and then set ms accordingly? But thanks for your help
 
The ma is the current needed to make it trip. The ms is the delay so if you set at 300ma with a 300ms delay the device will allow 300ma of fault to flow for up to 300ms before it trips.
Hi my settings I can choose from are
Ms is
0 is 0 ms
0.1 is 100 ms
0.2 is 200 ms
0.3 is 300 ms
0.5 is 500 ms
1 is 1000 ms
2 is 2000 ms
3 is 3000 ms
mA is
0.03 is 30mA
0.05 is 50mA
0.1 is 100mA
0.3 is 300mA
0.5 is 500mA
1 is 1000mA
3 is 3000mA
5 is 5000mA
10 is 10000mA
Is that right?
 
So how would I work out my ms?

My mA would be 300mA

So i would test with no time delay eg it trips at 100ms then I can delay that with 0.3 ms making my overal 400ms which would be within my trip time for x1 as time delayed RCD should trip within 130ms to 500ms?
 
As far as I can tell you are installing an RCD at the origin of the installation to ensure that on an earth fault the supply will be disconnected within the required time stated in table 41.1.
Since this is a TT installation and assumed to be at nominal 230V the disconnection times would be 0.2s (200ms) for final circuits and 1s (1000ms) for distribution and >32A final circuits (63A if sockets present).
Your tester should be able to measure a time of up to 500ms on a 1 x I∆n test for a type S RCD, or 300ms if not time delayed).

If all your final circuits have 30mA RCD protection then a 300ms time delay would be acceptable, if any final circuits <=32A (<=63A with sockets) are not protected by a 30mA RCD then you would need to reduce the total trip time for the upstream RCD to less than 200ms.
However in order to ensure that 30mA RCDs tripped in preference to the main RCD the time delay should not be reduced below 40ms (100ms is a good compromise)

The RCD tester should be correctly set up so the test parameters are for a type S RCD, (there will be a 30s delay in testing when set to type S) the RCD should ideally not be connected to any outgoing loads at the time of testing and there should be no other circuits running on the same supply that may introduce mains transients (motors and switching power supplies,etc.).
 

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