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Topic Title: Earth Leakage testing rack with UPS
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Created On: 16 April 2014 11:16 AM
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 16 April 2014 11:16 AM
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cblackha

Posts: 79
Joined: 21 January 2003

I'm trying to perform an earth leakage test on a rack of equipment containing a UPS.
The UPS is connected between the input socket and the rest of the equipment (essentially a PC and a mains-dc PSU powering everything else)

When I connect my Metrel OmegaPAT tester to the device I get the message: VOLTAGE CONNECT TO SOCKET FROM APPLIANCE

A quick Google has suggested that some PAT testers get confused because UPS input filtering is normally asymmetric.

Have others seen this problem?

Charlie
 16 April 2014 11:21 AM
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AJJewsbury

Posts: 11461
Joined: 13 August 2003

Is the UPS perhaps an older American origin design? They had a habit of not isolating the supply N/PE when running off batteries (in an attempt to keep a N-PE link) which can give the impression of it back-feeding voltage towards the mains. I believe the latest standards now require proper isolation of both live conductors.
- Andy.
 16 April 2014 11:44 AM
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cblackha

Posts: 79
Joined: 21 January 2003

UPS is made by Eaton, and I have a CE DoC citing EN 62040-1 which is a current standard.
I don't know if 62040 uses a specific measuring circuit, but I have no problem if I unplug the UPS or if I bypass it

Charlie
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