Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Helpful Answer
  • Replies 1 reply
  • Subscribers 31 subscribers
  • Views 711 views
  • Users 0 members are here
Options
You may also be interested in

voltage withstand testing

Udtwmc

I've been asked to test an industrial machinery control panel assembly to BS EN 61439-1. One of the tests is voltage withstand. The control panel will be at 'distribution level', category III so needs to pass at 4kV.

I have a Chroma HIPOT tester (designed for withstand testing) which is capable of delivering upto 5kV RMS with a short circuit current (cut-off) upto 20mA. The 61439 standard, however, asks for the test equipment to be capable of delivering a short circuit current of 100mA ('test leads shorted together'). From what I can tell, most widely available hipot testers also cut-off at 20mA, I did eventually find one tester capable of delivering 120mA but it is eye-wateringly expensive!

Question is, if my HIPOT equipment passes or fails a circuit under test at 20mA would you say this a more stringent test result than at 100mA so therefore meets/exceeds the standard? I'm possibly missing the point? I realise it's not as powerful as the 100mA equipment but in my mind if the test fails at 20mA then I'd be on the more cautious side  i.e. the insulation resistance is poorer, no?

I'd just add that I would buy a tester that goes to 100mA if they were readily available.

Parents
  • +1

    Assuming that nothing breaks down or flashes over, the short circuit current of the hipot tester you choose is not relevant to the usefulness of the test result - you expect only micro-amps to flow, and the voltage to stay at the full 4000V or whatever for the required time.

    A pass is a pass.

    Clearly of something does let go, then a machine with higher current limit will make a bigger bang and perhaps be more dangerous to the operator, and the point of failure will be that much more easy to locate by nose eyes and and ears ;=)

    But a small flash-over is still a fail.

    Also, at the risk of telling granny how to prepare eggs, please do be really careful - such equipment is lethal if the test voltage escapes and ends up across the person  and note that any normal SPD will operate and probably be destroyed by such a test - think very hard about what exactly is included in the  test.

    Beware that a few kV will both track over any surface, but more so (can be a few cm) if damp or vvery dusty, and will also jump an air gap of a few mm.

    Mike.

Reply
  • +1

    Assuming that nothing breaks down or flashes over, the short circuit current of the hipot tester you choose is not relevant to the usefulness of the test result - you expect only micro-amps to flow, and the voltage to stay at the full 4000V or whatever for the required time.

    A pass is a pass.

    Clearly of something does let go, then a machine with higher current limit will make a bigger bang and perhaps be more dangerous to the operator, and the point of failure will be that much more easy to locate by nose eyes and and ears ;=)

    But a small flash-over is still a fail.

    Also, at the risk of telling granny how to prepare eggs, please do be really careful - such equipment is lethal if the test voltage escapes and ends up across the person  and note that any normal SPD will operate and probably be destroyed by such a test - think very hard about what exactly is included in the  test.

    Beware that a few kV will both track over any surface, but more so (can be a few cm) if damp or vvery dusty, and will also jump an air gap of a few mm.

    Mike.

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines