RCD tripping times at 1x and 5x

[atm84]

I understand that when carrying out RCD testing an RCD should trip within 300ms at 1x and 40ms at 5x but is it common that on occasions for the RCD to trip quicker at 1x than 5x. I never had it occur personally.

I am just looking at some old certs and on some circuits the RCD is tripping marginally quicker at 1x than 5x.

Any thoughts?

 

[Pete999]

Do you have a copy of the OSG? all the info regarding trip times of the different types of RCDs are contained within.

 

[Richard Burns]

Usually 5x is quicker than 1x, however the older RCDs are very close in trip time and the meter variance and supply condition could change the value slightly.
The recorder may have swapped them around by mistake.
If the 5x was done first and the RCD had not tripped for a while then it may be initially slow to respond.

 

[atm84]

Do you have a copy of the OSG? all the info regarding trip times of the different types of RCDs are contained within.

Yes I do but the OSG does not tell you the results if tripping times for every install in the country does it?

I am fully aware of the max permitted times. My query is: is it unlikely that the 1x results can be quicker than the 5x.

 

[atm84]

Usually 5x is quicker than 1x, however the older RCDs are very close in trip time and the meter variance and supply condition could change the value slightly.
The recorder may have swapped them around by mistake.
If the 5x was done first and the RCD had not tripped for a while then it may be initially slow to respond.

Thanks. I had first thought that they may have swapped them round by mistake however on some results the 5x is marginally quicker (which is what I would expect)

 

[Guest77]

Yes I do but the OSG does not tell you the results if tripping times for every install in the country does it?

I am fully aware of the max permitted times. My query is: is it unlikely that the 1x results can be quicker than the 5x.

It will be rare but not impossible for this to happen. X5 readings are usually a for example around 10-15 to X1s 22-29 on a standard RCBO, these times are totally made up, just giving examples.

 

[telectrix]

you may have a female RCD.. totally unpredictable and unstable.

 

[atm84]

They are all approx 27 ms. I'm wondering if they have read the results in correct as it can differ at 180 degree of cycle.

 

[Flanders]

I've had them trip at the same times but very rarley normally around 19ms but at different cycles , on the report you enter the highest value for 5s and the higher value for 1s so thie would not show up on the report