I recently designed a piece of in-house gear that uses the PCB as part of the protective earth GND return. At first I thought I would be forced to use a wire(s) only (which was awkward given the mechanics of the unit) but then was convinced that EN61010 did not require it. To get around the via issue we kept the path on one PCB layer. We designed for well over 20 amps continuous. The bare metal rear panel is connected to the power connector GND with the standard YELLOW/GREEN wire. The cabinet and front panel are connected through the PCB with either metal spacers or a metal bracket. When testing this do I return the current through the rear panel only, or do two more tests using the cabinet and the front panel? The cabinet and the front panel do not have dedicated GND connections or any unpainted metal.
Dave Cuthbert Micron Technology From: Chris Maxwell [mailto:[email protected]] Sent: Tuesday, February 04, 2003 11:25 AM To: Lou Aiken; Peter L. Tarver; [email protected] Subject: RE: EN60950 protective conductor test (was Re: Circuit Breaker Tripping Dring Fault Tests) PC traces are easier to assemble and the assembly can be done in a tighter space. I think (just an opinion) that proper design could make this type of system more reliable as well with less chances of wires coming loose... > -----Original Message----- > From: Lou Aiken [SMTP:[email protected]] > Sent: Tuesday, February 04, 2003 11:36 AM > To: Peter L. Tarver; [email protected] > Subject: Re: EN60950 protective conductor test (was Re: Circuit Breaker Tripping Dring Fault Tests) > > > Why not provide a fuse to prevent deterioration of the PE trace on a PCB? > > Joking of course, but now that I have your attention, I would like to see > this thread move away from the physics and discuss what practical reasons > there are for using PC traces to provide earth fault circuits. > > > Lou Aiken, LaMer LLC > 27109 Palmetto Drive > Orange Beach, AL > 36561 USA > > tel ++ 1 251 981 6786 > fax ++ 1 251 981 3054 > Cell ++ 1 251 979 4648 > ----- Original Message ----- > From: Peter L. Tarver <[email protected]> > To: <[email protected]> > Sent: Tuesday, February 04, 2003 9:53 AM > Subject: RE: EN60950 protective conductor test (was Re: Circuit Breaker > Tripping Dring Fault Tests) > > > > Not quite. I^2·t will tell you the let through current of > the copper trace, but will not necessarily tell you if the > construction will be compliant. The compliance criteria for > this test include: > > * no damage to the trace (no lifting, probably no > discoloration) > * no damage to the PWB (no delamination, burning; I don't > know if this includes burning off of solder mask) > * before and after earthing impedance must comply with the > 0.1 Ohm maximum impedance > * no change in earthing impedance greater than 10% of the > before and after earthing impedance results > > There is also the much more variable solder in the earthing > path. While manufacturing techniques have come a long way > in terms of consistency, the amount of solder in a joint and > the quality of the joint itself can play a significant role. > It should be expected that a lower melting point solder will > perform less well than a higher melting point solder. > Appropriate process controls will have a positive effect. > > These are some of the reasons some form of safety agency > factory auditing of this type of construction is normal. > > > Regards, > > Peter L. Tarver, PE > Product Safety Manager > Sanmina-SCI Homologation Services > San Jose, CA > [email protected] > > > > -----Original Message----- > > From: Chris Maxwell > > Sent: Tuesday, February 04, 2003 5:32 AM > > > > > > Exactly! > > > > Chris Maxwell > > > > > > > -----Original Message----- > > > From: drcuthbert [SMTP:[email protected]] > > > Sent: Monday, February 03, 2003 7:50 PM > > > > > > What is needed is the I squared t rating of the > > breaker. Then the (I^2)(t) > > > rating of the PCB. Then you know if the PCB can > > take it. > > > > > > Dave Cuthbert > > > ------------------------------------------- > 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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 > > > > > ------------------------------------------- > 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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
