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Hi John: > Could it be that the authors assumed that the layers could separate, > locally and perhaps minutely, since there is no (?) practicable way > (maybe ultrasound?) to determine for sure that they don't. If they do, > the atmosphere in the gap may contain all sorts of stuff that could > impair the surface resistivity of the layers, and even promote tracking. > > Just conjecture: someone who knows should explain for certain. Your point is taken. IEC 60664-3 specifies peel strength testing for coatings as well as other conditioning tests to determine adherence. IEC 60664-3 also specifies partial discharge testing for such constructions. I mentioned both cement and amalgam as a means for a strong joint as well as an air-exclusion joint. The dimensions for distance through insulation start at 0.01 mm for 330 volts peak. Another point is 1.2 mm at 4 kV peak. This second point will indeed break down if there is any air whatsoever (unless the field is exactly homogeneous). See IEC 60664-1, Table A1. Best regards, Rich 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
