rcd ups zs

[tom1]

hi guy, did a cu change both rcd up the zs by 0.6,

what i did was loop test at incoming side of the rcd result 0.10, then on the out going side of the rcd 0.70.

any idear why, tighted all connection

thanks

 

[sellers]

deffinate problem there!

Did you catch the busbar properly with the clamp (see my bad connection thread)

I'd try switching the rcd on and off a few times see if it might be some dust or some bad connection inside, failing that return it! 0.6 is a lot!

 

[tom1]

both rcd, they are clamped on but i test on the screw anyway,

flicking on and off might work i remeber it working for a cooker switch now you mention it

thanks

 

[sellers]

aye I'd give it a try mate, could have been stored in a damp place and suffered some surface oxidisation on the contacts

 

[tom1]

will in a bit but i have tested the rcd so been off and on a few times will flick its another ten

---------- Post Auto-Merged at 21:50 ---------- Previous post was made at 21:28 ----------

tried it still the same

 

[sellers]

Take them back mate, something not right there!

 

[fletchflash]

could be something to do with your tester?

are you using low current test on both tests?

i had a problem like this with my fluke, it would add about .5 or so ohms on when using the low current soft test.

 

[tom1]

same test but one one incoming side the other on out going. the results are in with max zs but they dont add up

 

[steptoe]

Are you sure you are doing both tests using the no.trip.method,?

 

[tom1]

yes mate both done on non trip , my tester dose add about 0.2 on the non trip setting.

 

[fletchflash]

bit of a coincidence for both RCD's to be playing up, unless the boards been stored badly or bad batch etc

what brand are the RCD's?

 

[tom1]

bg nexus:coat

 

[fletchflash]

do you have any spare RCD's in your van you could fit and see if you still have problem?

 

[tom1]

yes mate got some wylex which i could changer tomorrow

 

[Doc Hudson]

Have you tried measuring the continuity across each pair of contacts in turn? in theory you will be getting a high reading across each contact if they are indeed faulty. If they both read out negligible <0.01ohm then it will point toward your Zs testing method.

Doc H.

 

[springcrocus]

Is it possible that the no-trip method of measuring Zs with your instrument is picking up some inductance-related discrepancy?

The principle of an RCD is two coils on a ferrite ring, one in each pole, balancing a magnetic field and a sense-coil picking up any imbalance. It may be that different manufacturing methods of RCDs cause problems of varying degree with different makes of testers.

And keep in mind that if you test at the incomers to the RCD using no-trip, the RCD is effectively out of circuit so whatever your tester normally does to "quieten" the RCD may now be interfering with the result. Just a thought...

 

[Nicky Tesla]

I dont know why exactly, but I have had this a lot lately myself.........is this another symptom of global warmingWet Fish

 

[tom1]

dont now whats causing it but i tried what doc said and it was about 0.6