Having diagnosed & fixed numerous problem sites that no one was able to fix, all I will is this, if you setup a dranetz unit and do an extended test you will quite often find 70V DC intermittent injection to earth, this most of the time is caused by leaky startup caps on a squirrel cage electric motor i.e. a compressor or the Air Conditioning unit.

I have diagnosed two sites where replacing the rectifier unit solved the problem, how it was doing it I have no idea, just that isolating the various earth circuits identified where the fault was, and replacing the rectifier solved the problem.


>Can you please explain how a defect rectifier can cause extensive DC to flow? A defect rectifier almost always means a short circuited diode, which will increase the AC current, and not cause any DC leakage.
>
>NB! I am an electronic engineer with more than 35 years of experience, I do know what I am talking about.
>
>>A faulty rectifier can give you a DC earth fault.
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>>>>>Earth faults are very hard to find, they come and go, so you have to monitor over an extended period.
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>>>>Will do. Thanks.
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>>>An earth failure will not create the errors in the pictures that you see. The power lines carry AC, which in the event of an earth failure will result in a alternating magnetic field. You will need DC to create a stable magnetic field which may cause the errors you reported.