Some very useful replies from all. What I've always wondered about, at least for class 1 construction, is just what is really being tested by the pri/sec hi-pot, when the customer chooses to ground the power supply's return.
Also,as some of our output-to-chassis "Y" caps are just 100V decouple caps, and because SELV to P.E. spacing and insulation requirements would never withstand reinforced test levels, how does the end-use installation ever get pri/sec hi-pot to pass without removing the unit from the chassis? R/S, Brian -----Original Message----- From: Tyra, John [mailto:[email protected]] Sent: Thursday, August 22, 2002 12:02 PM To: 'Peter Merguerian'; 'Brian O'Connell'; [email protected] Subject: RE: electric strength test I agree with Peter, per the standard, and most IEC product standards, you need two levels of protection from electric shock. In your case the y-caps provide one level (basic insulation) and the earth connection provides the second. As long as your earth path, between primary and secondary (I am assuming your secondary is connected or coupled to earth), will pass the Earth continuity test then it is unreasonable for the agency engineer to enforce reinforced dielectric requirements on the basic insulation Y-caps and you should be allowed to lift them during the test. You need to politely ask him to check with his superior on this one! I have not worked with 950 in many years now but I do remember that the Nordic agencies were requiring reinforced spacing and insulation between primary and earth for the reasons Peter cited. If you plan on selling in this region you should check all of the National deviations and maybe contact DEMKO (part of UL now) to see if this is still required for the Nordic countries................ -----Original Message----- From: Peter Merguerian [mailto:[email protected]] Sent: Thursday, August 22, 2002 1:09 PM To: 'Brian O'Connell'; [email protected] Subject: RE: electric strength test Brian, Your interpretation of the standard and application of the test between pri-sec is acceptable. You need to speak to a higher level person in the agency who is an expert! Please be advised that some countries do not have a reliable earthing system. Many end-product manufacturers design their equipment such that the power supply has double insulation or reinforced insulation between pri-earth. Norway is a good example. You may come across some distributors in Norway asking for DI or RI between pri-sec, even for Class 1 power supplies. Good luck at the agency! This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 http://www.itl.co.il http://www.i-spec.com -----Original Message----- From: Brian O'Connell [mailto:[email protected]] Sent: Thursday, August 22, 2002 3:57 PM To: [email protected] Subject: electric strength test ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc 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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
