Have you tried the RCD test with all the circuits OFF (i.e. no loads connected)

A 1A RCD is pretty deaf, but quite sensible for something big and 3 phase.

I presume the load is not something known to inject DC into the L-E loop as part of normal operation ?

How many RCDs of this type have you tested with this meter ? Normally I'd say 'try a known good one' but that may not be so easy, as it would be for 30mA  say.

So, while a 5A test is out, can your meter extend to a test at higher current say 2A?, and also does it matter which combination of phase and earth are selected for the test ? I'm wondering if swapping the phases would reveal that really one phase is slightly less sensitive.  For that matter are the supply voltages for all 3 phases present and correct ?

Is it actually doing a ramp test?

Not familiar with the tester, but after crooking my neck looking at the pic, it seems that it does indeed trip on the half cycle [29.6 mS], but at a test current >1.5 amps?


Again unfamiliar with the equipment, but as Sparkingchip asks...is this a ramp  test? I suppose, given the In recorded on the positive test it could be a ramp test, but smack on 1 amp for that is a bit flukey and probably unlikely.


A Metral user's input is required I think.

looking at  the manual  for the Autotest, pages 108-111 of the PDF, it does a hard trip at 1 times,  plus and minus 5 times and fineshes with two ramp tests (+/-). You have to reset the RCD at each step and as it steps through the tests it fills out that  table of results.

I see in the notes that if you call up type A it uses a pulsed waveform, and if yo call up AC it uses sine waves, and then either upto 1.5 times the nominal rating or 2.2 times for lower rated.


It would be interesting to know if it passes the tests for an AC type  device on both polarities.

I use a collection of separate testers, my first tester which I still have was a Robin KTS1620 multifunction which is as basic as you can get.


Currently my first choice meters are all Megger the insulation tester is a MIT420/2, loop tester a LTW320 and the RCD tester a RCDT320, however there are several other testers that don’t get regular use.


Over the last weekend I read through various websites and was considering if I should buy a new multifunction tester and put everything I already have on EBay which could potentially cover the cost of a new MFT.

I read this review of the Megger MFT1741 and it backed up some of the thoughts I already have in my head about testers and why I use the testers I do. Metrel owners have said to me in the past that if you get a duff test result on the automatic sequences you have to rerun the whole test sequence to confirm that what you tweaked you tweaked correctly and you have to scroll through lots of menus to get where you want to be.


Having just looked at the Metrel tester manual that Mike linked to I don’t think my current testers will be on EBay anytime soon, it all seems a bit over the top.


It looks like I► is the RCD test current that trips the RCD as Alcomax said being bang on 1000 mA seems unlikely.


 Andy 


Excuse the ► for delta, the choice of special characters  isn’t  much use.

Yes, all loads are disconnected by turning off Q1/Q2 (see attached image: "Schematics.PNG")


The RCD tester is also show in this image together with the "F3" RCD

yes that is a "ramp test" to the older hands among us.


If you can please re-test, lying to the meter that it is an AC type, and also verify that all phase to phase voltages are similar.

how is the meter connected - how are you choosing the phases to test - your diagram may imply live no1 and earth ,

does it work if you shuffle them  and use say L3 and earth ?


Is this the only RCD of its type you have tested with this meter, or has another one tested OK?


What is the NE voltage, and where is the NE bond ?