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On Tue, 15 Jun 2004 09:15:34 +0800, "Johnny" <johnny_le...@idvweb.com> wrote: > 1. Many books state that sometimes happening in ESD tests is that it failed > at lower level i.e. 4kV but passed at higher level , i.e.6k. Why does it > occur? One of the possible situation I can imagine - if there are some kind of spark gaps which can cause break-down at higher level, the effective impact of the ESD can be lowered at higher level. > 3. During the direct contact discharge test, do I need to use a grounded > probe to contact the EUT after the 10 discharge on each test point, or > contact it between each discharge? IEC 61000-4-2:1995/A2:2000 clause 7.1.3 says: "To simulate a single ESD event (either by air or by contact discharge), the charge on the EUT shall be removed prior to each applied ESD pulse." If you want to avoid the problem which can be caused when you tried to remove the charge, you can probably use grounding wire with higher resistance or iconizer to remove the charge, or simply wait for natural decay of the charge. Anyway, I guess I should recommend to revise the design to improve the immunity. Regards, Tom Tomonori Sato <vef00...@nifty.ne.jp> URL: http://homepage3.nifty.com/tsato/ 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 emc-p...@ieee.org 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: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
