Group, I am currently surge testing a handheld product with a Class II (ungrounded) "wall-wart" power supply. I have surge tested many class I (grounded) products here (in-house) before. This is my first Class II product.
Most standards, including EN 61326-1, specify different Surge voltages for line-line and line-ground tests. In my case, the minimum for immunity is 0.5KV line-line and 1.0KV line-ground My question is: What do I do about line-ground testing in my case? My DUT has no ground line. I can think of two opposing lines of reasoning. Conservative: The Surge generator is simulating a lightning surge. Lightning has no regard for whether a product has a ground line or not. I assume that lightning can and will make a line-ground surge potential present at outlets into which Class II products are plugged. As such, I should set the Surge generator for Line-Ground coupling, perform the test, and see what happens to the DUT. Even though the DUT has no ground connection for the surge return path, it is still valid to see what a "common mode" surge would do to the DUT. I assume that some of the surge current will flow through the DUT and return to ground via line-ground capacitance of the coupling/decoupling network of my Surge generator. This is the safe approach when considering compliance, but am I risking damage to the coupling/decoupling network by forcing Surge current through it? Literal: The test spec says line to ground coupling, my DUT has no ground connection. I don't perform line to ground surge tests. I have read my copy of IEC 1000-4-5:1995 and found nothing that specifically addresses this. I am left to use one of the two above lines of reasoning. What line of reasoning do you use? Chris Maxwell, Design Engineer GN Nettest Optical Division 6 Rhoads Drive, Building 4 Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
