thanks ...that could indeed be it.ESD?
I'd expect at least 1500 VAC/5 secs for 230/400 V CAT II mains input.Surely a 500V isolation test is all thats needed?
Thanks, its a megger FT4 flash tester. Its AC. It can go up to 4kv.What kind of test according to safety standards is actually performed? AC or DC?
...thanks, if i play the "ESD card" on them, their eyes will roll....because they handle FETs on other of their products and dont get failures. And in fact, they have a similar product to the one described, and it uses thyristors instead of FETs to do the switching, and they dont see failures on that one...and dont see the described control card failures.ESD may cause late / long term faliure.
Thanks, but all the usual mains clearances and creepages have been adhered to. Nothing is "exposed" so to speak.Might be that the test is inappropriate. You didn't yet explain what kind of isolation is implemented in the instrument, if parts of the the circuit are exposed (external LV interfaces or control elements).
Thanks, thats a great point, of course, in this case, we are just doing flash testing and not surge testing.I fear however that mains connected MOSFET can't resist surge tests without overvoltage protection, e.g. MOV or TVS diodes.
Typically no because the voltage can't propagate to SMPS switches. But post #1 and post #2 don't talk about normal SMPS (e.g. flyback) switches but a kind of dimmer. Would need to see circuit and test procedure to be sure that a fraction of test voltage doesn't appear between drain and source.I guess the main question here is....Is it possible for an NFET in a normal offline SMPS to fail due to doing a flash (hipot) test?
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