Hi Ralph: "My understanding that “clearance” is distance through air (the insulating medium for clearance), not through solid or liquid insulation." True.
"Clearance distance is a function of peak voltage and air pressure." True. "The testing of solid insulation is generally done using an impulse withstand voltage test." Depends on the standard. Its the first option in IEC 60664-1. "Clearance is tested using steady-state d.c. or the rms equivalent of an a.c. test voltage." In IEC 60664-1, the first option is an impulse withstand test, followed by peak sinusoid and DC. IEC 60664-1, 6.1.2.1, Note 1 says "The electric testing of clearances will also stress the associated solid insulation." Solid, air (clearance), and surface (creepage) distance are always in parallel. They cannot be tested separately. See attached illustration. Best regards, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to EMC-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
