Kewtech kt63 no trip function

[Paddington]

hi whilst testing ELI on lighting circuits, using kewtech kt63 on loop no trip function, test keeps tripping rcd once polarity and voltage is confirmed. I know the kt63 tests at 250v in this mode, but it shouldn’t trip the rcd, anyone else experienced this? Is it calibration time? Is it me? Is it the rcd? Anyone’s thoughts, and I know the calculation is Zs =(Ze + r1r2), a bit frustrated the damn things keep tripping, upstairs and downstairs, separate circuits, separate rcds, both trip.

 

[Paddington]

If you're into the CU, perhaps dis the RCD outputs and test separately?

That’s a possible, rcds tested well though, highest 34ms at 1x lowest 14ms at 5x not overly quick or sensitive. No trips at 1/2. Whole installation is good and tests as you would hope to expect!

 

[Martyn Fletcher]

My 63 has been a great buy, this one is strange. No doesn’t have ramp the 65 is a step up from the 63.

Um! The KT63 DOES have ramp test. It's on the little button top left with the x1/2, x1 and x5.
See picture...

 

[Paddington]

If you're into the CU, perhaps dis the RCD outputs and test separately?

That’s a possible, rcds tested well though, highest 34ms at 1x lowest 14ms at 5x not overly quick or sensitive. No trips at 1/2. Whole installation is good and tests as you would hope to expect!

Um! The KT63 DOES have ramp test. It's on the little button top left with the x1/2, x1 and x5.
See picture...

doh yes of course it does! Deliberate mistake, honest.

 

[Pete999]

Yeah that’s the formulae I used, I was to lazy to type plus signs and brackets in right places!

Right "to lazy" doesn't bode goodfor the future.

 

[happysteve]

I've never had a problem where my KT63 trips an RCD on no-trip loop (so far - not saying it'll never happen), though I have had issues where it refuses to take a test. This has usually turned out to be a problem with the neutral... for instance, this socket-outlet had a decent R1+R2 value, but would not do a no-trip Zs

You can see the degradation on the neutral terminal.

If you're having trouble measuring Zs on an RCD circuit, you can always use "The Alternative Method for Measuring Zs," using "high current loop" setting.

 

[happysteve]

Interestingly, I've found that the KT63 will do a 2 lead "high current Zs" test on a circuit protected by a 100mA time delayed (type S) RCD without tripping it.