Scenario: You are doing an inspection and test and you there is ELV wiring. The transformer is labelled SELV. Can you tell me the correct way to IR test. Is it 250 or 500 applied between the conductors of both circuits with the transformer disconnected, OR is it just 250 between the terminals of the transformer especially with respect to earth? Would this damage the ELV side?
SELV testing
- Thread starter pompeygit
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You must use some common sense any diodes will likely be damaged by 500 volt.
Due to inductance etc. there is likely on many circuits to be some current flow.
Inspection is main thing and if by inspection you can't be sure as to if a 250 volt insulation will do damage or not you can either use multi-meter and be satisfied with that or give a code 3.
One has the same problem with PAT testing and most testers only give Class III a visual inspection.
Some times you can see it is a simple bell and no problem with insulation test and sometimes where SELV cable is running with LV cables it may be prudent to disconnect both ends and test cable.
I often wonder if it is worth it as next inspection and test 90% of faults are still there.
Eric
Due to inductance etc. there is likely on many circuits to be some current flow.
Inspection is main thing and if by inspection you can't be sure as to if a 250 volt insulation will do damage or not you can either use multi-meter and be satisfied with that or give a code 3.
One has the same problem with PAT testing and most testers only give Class III a visual inspection.
Some times you can see it is a simple bell and no problem with insulation test and sometimes where SELV cable is running with LV cables it may be prudent to disconnect both ends and test cable.
I often wonder if it is worth it as next inspection and test 90% of faults are still there.
Eric
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