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brenfox

I was conducting a zs test on a 3 phase isolator and the terminals were sparking and snarling when i placed my probes onto them. This has never happened before and i am struggling to understand why it happened on this occasion. It was a 3 lead test: live,neutral, earth etc. It happened across all 3 phases but it gave me results of 0.85ish ohms which seemed correct.
 
This dos not sound at all good.
I would initially think that all the terminals were loose on the cores, but this sounds extreme for every termination.
Are you also sure that you were not testing phase to phase and earth, which could well be straining the meter if it is not designed for 400V.
Generally it is a good idea to find a fault before continuing with a potentially hazardous operation.
 
If you get a dirty terminal or poor conection of the test probe to the terminal you are testing you could get a spark i have seen this on the earth terminal when it was corodid
 
I was replacing a TPN board for a new TPN board then conducting an NIC report. My company had given me 4 hours to complete the job (ridiculous i know). You are right in thinking loose terminations create sparks etc. Terminations were tight, the isolator had a neutral, earth and 3 phase. 3 lead test with my trusted tester and sparks were flowing. I got the ZS reading I was hoping for. Been doing this a while now and was hoping someone was going to explain the science behind it!Phase to phase and my tester would definitely let me know!
 
I was replacing a TPN board for a new TPN board then conducting an NIC report. My company had given me 4 hours to complete the job (ridiculous i know). You are right in thinking loose terminations create sparks etc. Terminations were tight, the isolator had a neutral, earth and 3 phase. 3 lead test with my trusted tester and sparks were flowing. I got the ZS reading I was hoping for. Been doing this a while now and was hoping someone was going to explain the science behind it!Phase to phase and my tester would definitely let me know!
What, 4 hours to replace a TPN DB and test?? How many circuits?
 
What, 4 hours to replace a TPN DB and test?? How many circuits?
Yep. 4 of 3 phase circuits and 7 single phase circuits. Pinewood studios in Cardiff. Massive place with restricted areas. I am currently seeking other opportunites!
 
Crazy wanting it done in 4 hours that!

It happens on my old AVO earth fault meter, it doesn't have a test button, as soon as power is on the leads it starts. So it used to spark as you put the leads on but if you put the leads on in a certain way it wouldn't do it.

That's on old meter though...what meter are you using?.



Sent from my E5823 using Tapatalk
 
Crazy wanting it done in 4 hours that!

It happens on my old AVO earth fault meter, it doesn't have a test button, as soon as power is on the leads it starts. So it used to spark as you put the leads on but if you put the leads on in a certain way it wouldn't do it.

That's on old meter though...what meter are you using?.



Sent from my E5823 using Tapatalk
I mainly use my Kewtek 17th edition testers. I like using dedicated testers rather than the multi function kind. Still unsure why it happened, only logical explanation for sparks is loose terminals.
 

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