DC Hi-Pot testing a Transformer & Cables
DC Hi-Pot testing a Transformer & Cables
(OP)
I need to test the insulation resistance of a 3-Core cable, but one end is still attatched a 3.3kV/400V 1.5MVA oil filled trandsformer.
I'm planning to connecct 5kV to all three cables and the earth to the Cable Armour, which is connected in turn to the Transfomer frame.
That will check the insulation of all three cores to the steel armour.
I can't check from a single core to the other two cores earting one of the cores would mean path from the live cable through the transformer windings to earth, but is ther any other tests availible to me?
I'm planning to connecct 5kV to all three cables and the earth to the Cable Armour, which is connected in turn to the Transfomer frame.
That will check the insulation of all three cores to the steel armour.
I can't check from a single core to the other two cores earting one of the cores would mean path from the live cable through the transformer windings to earth, but is ther any other tests availible to me?






RE: DC Hi-Pot testing a Transformer & Cables
This has been discussed here many times in depth, you can catch up on the discussions by searching the forum for previous threads on the subject.
RE: DC Hi-Pot testing a Transformer & Cables
Regards
Marmite
RE: DC Hi-Pot testing a Transformer & Cables
The cable terminations are in a compound filled cable box.
and it is a Utility customer. WE discussed removing the compound but a concern was raised that heating the compound may result in damage to the Transformer bushings.
It is exactly a go/no go test that is wanted prior to energising.
it's a 3.3kV Transfomer. Is testing at 5KV too high for an existing cable & transformer. Normally each cable or winding would only see a voltage of 1.9kV above earth. Voltage of 3kV to ewarth be more appropiate>
RE: DC Hi-Pot testing a Transformer & Cables
Regards
Kyle
RE: DC Hi-Pot testing a Transformer & Cables
RE: DC Hi-Pot testing a Transformer & Cables
http://www.eng-tips.com/viewthread.cfm?qid=248906
RE: DC Hi-Pot testing a Transformer & Cables
And you get the added bonus of using a Megger test set at 1000VDC instead of a DC hipot at 1000VDC which will prevent the DC Hipot Police from coming to your house late one night.