We use four florescent screw-in lights in our 3-metre chamber and detect some emission 3dB or so above the "noise floor".
Ralph McDiarmid, AScT Member Technical Staff Engineering Services Xantrex Technology Inc. -----Original Message----- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Thursday, October 31, 2002 9:49 AM To: EMC-PSTC (E-mail) Subject: Shield Room Lighting Greetings all, I wanted to share an experience and I hope benefits someone else. My past experience with shield room lighting is that incandescent bulbs frequently burn out, about once every 2-3 months. I tried ruggedized lamps of various sorts, still with the same results. Obviously, I wanted to avoid florescent lighting because of the huge fields they radiate. After some investigation and discussions with co-workers, it became apparent that the problem is the line filter for service power in the room and the tungsten filament in the bulb. These line filters are typically have a really large line to neutral capacitance which significantly lowers the source impedance of the line. Coupled with this, tungsten experiences a fairly high in-rush current owing to it's very dynamic negative temperature coefficient. I toyed with idea of using inrush limiters but I thought there had to be a reliable low-tech solution. And at all costs, whatever solution I used, I wanted to avoid injecting unwanted RF noise into the room. I discovered traffic light signal bulbs. Available from a few sources, these bulbs have at least 5 filament supports, heat dissipaters and reflectors and are designed for continuous on/off operation in all sorts of weather conditions. They even keep working when the hanging fixtures bang into each other in wind storms. I also learned that these bulbs have about a 1 to 2 year life expectancy in these conditions, so I tried it out in my room. So far, I've logged a full year of use on 4 x 150W bulbs with no burn out. And no, I don't just leave them turned on. If you want to try this, do it soon because it appears that these bulbs may become a thing of the past and prices may be driven up. Over the last few years, many cities and counties are replacing their incandescent bulbs with the new LED bulbs and with great success. As soon as a white LED light becomes available I may try it out, although I guess I could use red LED lamps since I used to be in the navy. Best regards, -doug Douglas E. Powell Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, CO 80535 USA _______________________________________________________________ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. ------------------------------------------- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com 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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com 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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
