Pete: Your example looks correct. I was aware of these sorts of situations, which is why my gut feeling was that the "no test" entries in table 5b were wrong, which prompted my question to the forum. I then allowed myself to be perhaps too quickly satisfied by Sylvia's response, which quite correctly pointed out that the 500V test for Functional is optional.
I agree that first principles tell us the hipot test (EST) in your point 7 should be required, but where is that stated in the standard? Table 5b) seems to be the only place where it says which insulation needs to tested. Jim Eichner, P.Eng. Compliance Engineering Manager Xantrex Technology Inc. e-mail: [email protected] web: www.xantrex.com Any opinions expressed are purely accidental. Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. From: Peter L. Tarver [mailto:[email protected]] Sent: Friday, December 05, 2003 3:26 PM To: EMC-PSTC - forum Cc: Sylvia Toma; Jim Eichner Subject: RE: UL60950-1 update Sylvia is right, at first glance. But all is not necessarily revealed by reading Table 5B and assuming ยง5.3.4 applies. The referenced column in Table 5B, Part 1, is for secondaries within ELV/SELV voltage limits to chassis and between independent secondary circuits of 'similar' circuit types. BUT ... one must be careful and read all of the applicable kibbles and bits. For instance, in reviewing Table 2G, Figure 2F with Table 5B: 1) an ELV Circuit and an unearthed SELV Circuit are within the same voltage limits where the referenced column of Table 5B seems to apply 2) assume the ELV Circuit has Basic Insulation to a Primary Circuit 3) also assume the SELV Circuit is unearthed 4) Figure 2F indicates ELV to unearthed SELV requires Supplementary Insulation (S1), but there's no Supplementary EST value in Table 5B 5) Table 2G, for S1, refers to Condition 2 of that table 6) Table 2G, Condition 2 states that the worst-case voltage involved for the Basic Insulation is used to determine the insulation requirements, in this example, between the ELV Circuit and the Primary Circuit 7) the ELV Circuit to unearthed to the SELV Circuit requires an EST based on Supplementary Insulation in one of the five columns (two through six) of table 5B If this example is faulty, someone let me know. Regards, Peter L. Tarver, PE [email protected] > From: Sylvia Toma > Sent: Friday, December 05, 2003 11:00 AM > > There is no test for Basic, Supplemental, or > Reinforced insulation since > for those three categories; you need to meet the > spacing requirements. > > For Functional insulation, you can conduct hipot > test in lieu of spacing per sub-clause 5.3.4. > > > From: Jim Eichner > Sent: Friday, December 05, 2003 10:15 AM > > I have a question about 60950-1 based on what I > suspect might be an error. > > In Table 5B listing voltages for hipot tests, the > second last column from > the right shows a 500V test for Functional > insulation but no test for Basic, > Supplemental, or Reinforced insulation. Is this > an error or am I missing > something? It seems to me that this should be reversed. > > Thanks, > > Jim This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ 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://www.ieeecommunities.org/emc-pstc
