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Topic Title: 3 Phase Earth Loop Testing
Topic Summary: Fluke 1653
Created On: 07 March 2006 10:09 PM
Status: Read Only
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 07 March 2006 10:13 PM
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Posts: 38
Joined: 04 May 2005

Hi All

I need to do a PIR for an industrial unit. No probs at all except for what do I put down on the cert for Earth Loop if I test a 3 phase circuit and no neutral. I've done the I & T but never come across this one before. I can test line impedance between any 2 phases, but does anyone know how to earth loop a motor cicuit for example, i.e. with no neutral? Any help would be appreciated.

Thanks in advance

Edited: 07 March 2006 at 11:01 PM by kbro6
 07 March 2006 11:12 PM
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Joined: 17 March 2005

Measurement of PEFC on 3 phase motor at remote end
Check your instrument instruction book
Live testing safety checks
Remove loads
Remove star delta links on motor. (disable running mode).
Set instrument to PSCC or 20 ohms
Place red lead on incoming L1 in motor term chamber. Black on earth point
If instrument has earth lead as well put this on earthing point.
Switch on circuit
Repeat for L2 and L3
Do not test between phases. Damage to meter.
If your instrument reads PSCC and loop impedance then record as required
If not do the calcs with voltage = L-E.
Reinstate motor terminations and box up.
 08 March 2006 12:12 AM
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Joined: 18 January 2003

The question was how to do a earth loop and the answer was how to do prospective short circuit?

I would say two wire tester phase to earth, with my old Robin KTS1620 three wire tester phase to earth with the neutral connection onto the earth as well,
test each phase and record the highest of the three results.

I've just got a new Megger LT320, but I haven't read the relevant part of the CD yet, apparently I can go Phase/ Phase/ Earth, to late to look tonight I'm off to Bed!

 09 March 2006 11:11 PM
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Joined: 04 May 2005

Thanks both

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