http://www.ieee-pses.org/symposium http://www.emc2004.org/ -------------------------------------------------- David, Breakdown is the sudden and uncontrolled increase in current through an insulation system. I am not familiar with the brand of testers you mention below, but I do know of some make of dielectric withstand test equipment that incorporates a detector that looks for the r.f. current that flows just BEFORE insulation breakdown occurs. While the presence of such a current may be of interest for diagnostic purposes, it is of no interest when performing a regular dielectric withstand test since it does not detect breakdown as defined above. Since you say the disparity occurs after abnormals, you are presumably speaking of a type test? Personally, I would never select a r.f. detect mode when performing a type test for the reason given above. If you know what the correct setting is, perhaps this methodology has use in routine testing since it has the possibility for spotting dielectric weaknesses. You test currents are also different. Remember, what you are looking for is a rapid increase in current. My preferred way of checking this is to place an ammeter (preferably analogue) (and definitely located in the 'earthy' side of the supply) in series with the insulation under test. By increasing the test voltage slowly you can see if the current is rising proportionally to the voltage until it hits some arbitrary trip point set on the dielectric tester and cuts off: if this is the case, you may not have a breakdown and you will need to select a higher trip point and repeat the test. For example, you would naturally expect the ac current through the Y capacitors to follow this behaviour (which is why a dc test voltage for such applications is generally preferred). Your test current of tens of mA sounds like you are using an ac source. Perhaps one or both of the reasons above are why you and your NRTL are getting different results? Regards, Richard Hughes In a message dated 08/17/2004 21:34:41 GMT Standard Time, [email protected] writes:
Hello Group, I am currently in discussion with our NRTL regarding dielectric testing and the dielectric test analyzers settings and would like to have your input on the following: We both have the same analyzer (Vitrek 944i), EUT set-up, and are conducting dielectrics (reinforced and basic insulation) per IEC 60065. Only difference is that I have my analyzers ARC detect setting set to slow and test current set to 30 mA. The NRTL have their analyzer set to the defaults (fast ARC detect / 10 mA). When the test is conducted (after abnormals) our DUT passes and theirs fail. Just to double check when I input the same setting into the analyzer and re-conduct the test our EUT fails. This standard nor others that I've used make any reference to ARC detect settings, however I do recall coming across a standard that called out the current limits as being 35 or 40 mA (don't quite remember which one). How does ARC detect function (detailed) and is there a process that keeps such settings consistent between NRTL's? Any explanation and/or ideas on this would be greatly appreciated Thank you for your time, David Cereceres ------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
