Sounds more like a “ground loop” issue to me. Ideally, shielded rooms should be isolated from earth and then single-point grounded to earth using a ground rod. It sounds to me as if there may be multiple grounds, possibly via multiple AC line circuits. Are the AC line circuits to the monitors different from the circuit supplying the chamber, but using the same earth connection to the chamber wall? I suspect there’s appreciable current running through the chamber walls (common-impedance coupling).
Ken _______________________ I'm here to help you succeed! Feel free to call or email with any questions related to EMC or EMI troubleshooting - at no obligation. I'm always happy to help! Kenneth Wyatt Wyatt Technical Services LLC 56 Aspen Dr. Woodland Park, CO 80863 Phone: (719) 310-5418 Email Me! <mailto:[email protected]> | Web Site <http://www.emc-seminars.com/> | Blog <http://design-4-emc.com/> The EMC Blog (EDN) <http://www.edn.com/blog/The-EMC-Blog> Subscribe to Newsletter <http://www.emc-seminars.com/Newsletter/Newsletter.html> Connect with me on LinkedIn <http://www.linkedin.com/in/kennethwyatt> > On Sep 28, 2015, at 6:45 AM, Robert Dunkerley <[email protected]> > wrote: > > Hi, > > Has anyone ever had problems with EMI filters supplying EMC chambers before? > > When mains is applied to the filter for the chamber lights, there is > interference seen on the computer monitors outside the chamber. This happens > even if the lights are turned off in the chamber, but power supplied to the > filter. Looks like the noise is going down the mains cable into the > computers/monitors. > > The filter may have degraded, but I though they tend to just go completely? > > Thanks, > > Rob. > > > > > > > > This email has been scanned for email related threats and delivered safely by > Mimecast. > For more information please visit http://www.mimecast.com > <http://www.mimecast.com/> > - > ---------------------------------------------------------------- > 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] <mailto:[email protected]>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > <http://www.ieee-pses.org/emc-pstc.html> > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <http://product-compliance.oc.ieee.org/> can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > <http://www.ieee-pses.org/listrules.html> > For help, send mail to the list administrators: > Scott Douglas <[email protected] <mailto:[email protected]>> > Mike Cantwell <[email protected] <mailto:[email protected]>> > > For policy questions, send mail to: > Jim Bacher <[email protected] <mailto:[email protected]>> > David Heald <[email protected] <mailto:[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.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
