Rich, Ok. That makes sense. Thanks for the follow-up.
This is scary stuff! Jack Cook Xerox EMC Engineering -----Original Message----- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 2:11 PM To: jack.c...@cax.usa.xerox.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jack: > I'm having a problem with Rich's explanation in this particular case (I know > it's often true, though). How did resisitive heating occur *without* > current flow? It was clearly stated that the heater was switched OFF. I believe that the process I described takes a lot of time. It starts when the heater is first used, i.e., a heavy current through the plug and socket. The heating due to the contact resistance degrades the material between the blades of the plug due to pyrolysis, the decomposition of a material by heat alone. The decomposition results in unknown materials between the blades. Plastics are carbon-based. Decomposition of carbon-based materials tends to reduce the size of the molecule, and the material approaches pure carbon, a resistor. So, we can assume that these unknown materials are resistive. We will have a leakage current through the resistance. Once the leakage path is established, the heater does not need to be on for the process to continue. Since this isn't a "good" resistance, some elements will open, and micro-arcs will occur. These micro- arcs create new resistances, and the leakage current will continue to increase. And the arcs get bigger. Etc. I could be wrong... Best regards, Rich ------------------------------------------- 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: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
