Hi group, Let's take a Class II product with a telecom (TNV-3) and USB interface (SELV). There is a surge suppressor (GDT of 500V) from each of the 2 telecom wires to an internal reference ground that is also connected to the shield of the USB connector.
TO PROTECT THE USER FROM OVERVOLTAGES, a test to IEC60950, Cl. 6.2.2 is required, the impulse test of 6.2.2.1 is chosen. In Cl. 6.2.2.3, I notice that the GDT may operate as long as there is no damage to other insulation. This test will pass AND in real life, the user can be exposed to real surges with levels 1500V, 4kV, ... when touching the USB interface or any metallic part of the product. Question: Is this really the intention of the standard or am I missing something? Note: I make the assumption that TNV-3 to SELV Basic insulation is met and Clause 6.1.2.1 is not applicable. Best regards, Kris Carpentier Regulatory & Approvals - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
