I seem to recall that one of the earliest EMI problems was one that came from solenoids (well a version of one that held the core stationary and used the coil discharge). Resistor wire and resistor plugs reduced the problems to acceptable levels in cars. If you can find any of these parts without the resistance, substitute them into your car and listen to what happens.
- Bill --- On Tue, 9/22/09, Scott Douglas <[email protected]> wrote: From: Scott Douglas <[email protected]> Subject: Re: EMC Directive and solenoid valves To: "Price, Edward" <[email protected]> Cc: [email protected] Date: Tuesday, September 22, 2009, 1:13 AM In a past life I had a real problem with a solenoid causing serious EMC, primarily from the coil discharge. Diodes across the coil helped some, but we ended up having to create a soft drive and a discharge circuit in order to tame the unruly beast. So how anyone can say solenoids are benign from an EMC standpoint is beyond me. Scott Douglas Price, Edward wrote: -----Original Message----- From: [email protected] <http://us.m 396.mail.yahoo.com/mc/[email protected]> [mailto:[email protected] <http://us.mc396.mail.yahoo.com/mc/[email protected]> ] On Behalf Of Gordon,Ian Sent: Monday, September 21, 2009 12:32 AM To: White, Ian Cc: IEEE EMC & SAFETY PSTC Subject: RE: EMC Directive and solenoid valves Ian et al We manufacture solenoid operated vacuum valves (amongst other things) and obtained a statement from ERA to the effect that they were benign as far as the EMC directive is concerned. Ian Gordon When the solenoid is de-energized, isn't there a large and fast voltage generated? When a solenoid manufacturer puts a diode across the coil to limit the voltage, doesn't the large current flowing through the diode and coil create a spectral distribution of energy? Perhaps the Directive ignores the short duration burst, but I don't think you can call a solenoid coil completely benign. Ed Price [email protected] <http://us.mc396.m il.yahoo.com/mc/[email protected]> WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty - ---------------------------------------------------------------- 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]> <http://us.mc396.ma l.yahoo.com/mc/[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]> http://us.mc396.mail.yahoo.com/mc/[email protected]> Mike Cantwell <[email protected]> <h tp://us.mc396.mail.yahoo.com/mc/[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> <htt ://us.mc396.mail.yahoo.com/mc/[email protected]> David Heald: <[email protected]> <http //us.mc396.mail.yahoo.com/mc/[email protected]> - ---------------------------------------------------------------- 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]> - 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
