Hi Derek,
I would contact the engineering departments of both manufacturers and obtain information re. switchover times. Generally, switches optimized for ac only use have a "soft", or slower switch time. Switches for dc use have a fast "snap" action to reduce the chance of contact welding. Switches with both ac and dc ratings are a compromise. Contact spacing and switchover time will affect emi, so a case could be made that switches with similar geometry should have similar emi generation characteristics. Scott B. Lacey On 5 Jun 2008 at 10:40, Derek Walton wrote: > Hi All, > > I have been asked if there was a way to prevent testing a mechanical > switch for EMI. The background is that the exact aircraft switch was not > available at the time of the system EMI test, so a substitute was used. > The suitability of the correct switch is now being questioned since it > was not present during the EMI test. > > This is a mechanical switch with just electrical contacts. For immunity, > it should be blatantly obvious, but not so at our final customer. For > emissions, there is potentially a noise source during the few > microseconds as the contacts touch or open. However, this is a low level > signal, and similar contacts on the substitute device would have > exhibited similar noise had it been an issue. > > If anyone has suggestions on building a case why not to test this > mechanical switch I'd appreciate it. > > Thanks, > > Derek Walton > L F Research > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > 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] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
