Lou Aiken wrote >> ... what practical reasons there are for using PC traces to provide earth fault circuits. <<
One practical reason is, to cut costs and simplify construction. Some years ago a former employer designed and made a computer power supply with the safety ground on the board, and UL allowed it. It was necessary to make the board rugged enough at the grounding point to accept a standard, threaded stud, nut and washer combination; they would not budge on THAT. It survived fault current tests just fine. What we got from this was the ability to put everything, including an IEC power connector, on one board, and eliminate flying wires. I've also seen current requirements which could not be reasonably met using a PWB trace, and in that case, a heavy bus strap was soldered onto the board. This is a viable replacement where space or fabrication constraints don't allow for the heavy, wide traces high current incurs. This construction may be a reasonable answer to some of the issues here. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
