Ted Eckert's comments ring true. Something interesting happened this A.M. while HALT chamber running, my tech accidently opened the 100A breakers to the chamber, while intending to open a breaker to another machine. The resultant arcing propagated to a temperature sensor circuit external to the chamber that was added as a fail-safe to protect the UUT. No other damage found to any other downstream circuits. Power removed from panel and breakers removed to verify - it looks ok, but will probably replace by end of year. As for the temp sense stuff - that was my bust as design did not include surge immunity (cobbler's children have the worst shoes).
In another case, a molex connector to machine-shop equipment (rated for 16A) was disconnected while under 5A load. The connector pins were damaged and assembly had to be replaced. In factory, a particular connector was being re-inserted 3x or 4x, not powered, if the unit required troubleshooting. These same units were later traced to a hi field-failure rate (approximately 15% connectors failed after 1 year), so the factory tracking was downloaded and recall for these particular units implemented. The immoral of these stories is that a connector, unless specifically rated for a certain insertion duty cycle, should not be subject to multiple re-insertion cycles. Components intended to interrupt load current and/or are rated for multiple insertion cycles should be ok and will serve the Empire well if used per the mfr's conditions of acceptability. Brian From: Crane, Lauren [mailto:[email protected]] Sent: Friday, May 23, 2014 12:50 PM To: [email protected] Subject: [PSES] "exercising" connections for health? I am puzzling over a notion that it is prudent to exercise connectors in power circuits "every once in while" (e.g., disconnect and reconnect them). I suppose the underlying idea is to scrape the touching surfaces and potentially disrupt forming oxides or accumulated pollution. I saw the other day an article suggesting circuit breakers should be cycled every so often (~ once a year) for possibly similar reasons. Does anyone know of a code of electrical maintenance, or similar, that might support or refute this notion? Regards, Lauren Crane KLA-Tencor - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
