Run Test on PSU's....

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Run Test on PSU's....

Postby remedy234 » Fri Sep 14, 2012 10:17 am

Hi

We are currently working on a site where the customer has asked us to retest every power supply unit as we didnt do a run test, just tested the insulation.

Ive been doing this job 15 years and never done a run test, just an insulation test, am i doing this wrong now or doesnt the customer know what he's talking about?
remedy234
 
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Re: Run Test on PSU's....

Postby remedy234 » Mon Sep 24, 2012 8:53 pm

Anybody know if a run test is required on psu's?
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Re: Run Test on PSU's....

Postby Patnik » Tue Sep 25, 2012 9:51 am

Hi remedy234,

I always do a run test where possible as, in addition to maybe showing an abnormal current draw, it may expose a problem with excess earth leakage current. You don't say what sort of PSUs. Leakage problems are pretty rare but I have had problems with old, imported, high current PSUs coming over the 3.5mA max. Some rack mount PSUs and UPSs also come in high as they are designed for use in earthed racks not free standing. I've had a couple of PC PSUs (out of 1,000s) go high leakage when they fail but they could still be regarded as potentially dangerous if the PC is left plugged-in despite not working.

The pseudo-leakage tests on some of the newer testers don't seem to be accurate and sometimes don't register at all despite a differential run test showing leakage.

I work in an institution with it's own rules but if I paid someone to PAT a load of PSUs and they omitted all the run tests without consulting me then yes I'd ask them to come back and do it again. (An exception being genuine class 2 IT PSUs in an office environment.)

Nik
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Re: Run Test on PSU's....

Postby remedy234 » Tue Sep 25, 2012 11:06 am

Hi thanks for your reply

These are low voltage psu's, the chunky big plug type :)
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Re: Run Test on PSU's....

Postby Patnik » Tue Sep 25, 2012 11:14 am

Oh 'wall warts' with class 2 mark and CE mark? If that's the case then I agree that a run test is a bit over the top and HSE advice suggests just a formal visual check is needed if in an office environment.

Of course there are thousands of dodgy, sub-standard, imports about but a run test isn't likely to expose one.
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Re: Run Test on PSU's....

Postby remedy234 » Tue Sep 25, 2012 2:21 pm

Ha yeah wall warts :)

The thing is we have tested them all once but now been told its not to their specification as they want run tests on them all,

Think we'll be charging again
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