3 phase Zs test!!!!

[eskimo39]

Hi guys does anyone know if is possible to do a 3 phase Zs test on a fluke 1653b? I am currently halfway through s PIR at a factory and most boards I have tested have either being single phase or 3 phase with no RCD. However I have 2 outside motor/ pump sockets to test but neither have a neutral and both are on RCD. I have tried combining my earth and neutral wires but it still trips. Any ids?

 

[telectrix]

measure R1 +R2 on each phase. use highest reading and calculate Zs. ( R1+R2+Ze)

 

[WayneL]

Link out 'Line' to 'Earth' at motor/pump (after safe isolation), and test at the CU

 

[Mr Mark Sparks]

r1 and r2 seems the only safe option

you could bypass the rcd but not really recomended

 

[WayneL]

r1 and r2 seems the only safe option

you could bypass the rcd but not really recomended

What I suggested is no less-safe than performing an RCD test, a Ze test or a PFC test at the board.

 

[MFHEng]

If the equipment can be shut down and you or the customer have spare mcb's, remove the rcbo from circuit and replace with a spare mcb to do the test (provided your meter will do a 2 lead impeadance test).(this method introduces extra risk to you in altering circuit make up and should be considered carefully)

If the rcd is not an rcbo and seperate from the DB, bypass it/link it out and carry out the two lead impeadance test. (less risk to your self and the norm)

If your meter does not carry out 2 lead impeadance tests the option would be as telectrix's post. (the safest and most sensible option)

 

[Mr Mark Sparks]

What I suggested is no less-safe than performing an RCD test, a Ze test or a PFC test at the board.

sorry wayne bad choice of words on my part should of said r1 r2 is what i would do

 

[RETIREDSPARKY]

Check out GN3 page 76 on how to test Zs on motor circuits.

 

[MarkieSparkie]

Live testing (but particularly in an industrial installation) contravenes EAWR. If you require Zs this MUST be achived in the safest way possible, therefore R1+R2 dead + Ze Live but Installation dead. Only if isolation cannot be achieved or the test can only be done live (eg RCD test) is live testing of the installation valid under EAWR.

 

[brizospark]

Live testing (but particularly in an industrial installation) contravenes EAWR. If you require Zs this MUST be achived in the safest way possible, therefore R1+R2 dead + Ze Live but Installation dead. Only if isolation cannot be achieved or the test can only be done live (eg RCD test) is live testing of the installation valid under EAWR.

What a load of old horsedung in the real world if a spark can't safely carry out a Zs test live then they shouldn't be doing it. I'd like to see you use that method when you have 100 plus circuits to check. Anyway you say R1+R2+Ze how the hell can you justify taking Ze if you are contravening EAWR. Anyway what's wrong with doing it the easy way and taking 3 tests, each phase to cpc and recording the highest?

 

[telectrix]

What a load of old horsedung in the real world if a spark can't safely carry out a Zs test live then they shouldn't be doing it. I'd like to see you use that method when you have 100 plus circuits to check. Anyway you say R1+R2+Ze how the hell can you justify taking Ze if you are contravening EAWR. Anyway what's wrong with doing it the easy way and taking 3 tests, each phase to cpc and recording the highest?

his problem is that he can't carry out a Hi current Zs as the circuit is RCD. he can't carry out a no trip test as he hasn't got a neutral.