Happy Thanksgiving to one and all, Mr. Schlentz provides an informative analysis, but my reason for posting the question was purely the EMC aspects. How can such noisy devices be marketed while holding ITE to much more stringent limits? And if the FCC/broadcast industry were so concerned about rfi from office equipment in the '70s, why are they not much more concerned about what could be a significantly more widespread usage, lighting? In my particular case, I bought some reflector type bulbs that mount in recessed ceiling lighting fixtures. These are not movable. Therefore the standard FCC warning about moving the offender in the case of rfi is not applicable. Not to mention the much more important point, that the power line feeding the light runs across the ceiling and down the wall to the light switch, making the radiating source too large to get away from.
I made some AM band measurements, peak detection: Freq Ampl. MHz dBuV 0.45 98 0.55 94 0.63 92 0.75 90 0.83 86 0.88 83 0.94 82 1 78 1.2 73 1.4 72 1.54 70 1.61 68 1.68 67 1.73 69 These were rectification harmonics. If I turned on video averaging, they went away and left a nice spectrum of some cw switching activity at a much lower level. It is the rectification harmonics, not the switcher, that causes the problem. BTW, the noise was pure differential mode - there was no common mode component, which is to be expected for this two wire topology. Ken Javor > From: [email protected] > Date: Thu, 25 Nov 2004 10:07:38 -0600 > To: Ken Javor <[email protected]> > Cc: [email protected] > Subject: Re: fluorescent lamp rfi > > Perhaps you should reconsider using screw-in fluorescent lamps. I have > compared them with incandescent lamps that they are advertised to > replace, for example, a 27 watt fluorescent lamp with a 100 watt > incandescent lamp. The price was $7 versus $0.45. The observed > screw-in fluorescent lamp lifetimes were consistently less than 400 > hours (the claimed lifetime is about 9000 hours) and the measured > incandescent lamp lifetime is about 400 hours. I have also measured the > light output from screw-in fluorescent lamps and found the output after > the first 40 hours to be about 40 % of that of the incandescent lamp > (screw-in fluorescent lamp light output usually drops after a few hours > of use). It also may cost $0.50 to dispose of each fluorescent lamp in > your community.. > > Using $0.12 per kilowatt hour as the cost of electricity, the cost of > using a 27 watt fluorescent lamp is $7 + $0.12 * 27 * 400 = $8.30 and > the cost of using a 100 watt incandescent lamp is $0.45 +$0.12 * 100 * > 400 = $5.25 . To reduce the rf emissions may require a metal luminare, > metal conduit, and a filter. > > An incandescent lamp has a lower cost of ownership without considering > the reduced light output, the disposal cost, and the mitigation of rf > emissions. I think using incandescent lamps cost less than screw-in > fluorescent lamps. > > Best regards > Bob Schlentz > [email protected] > > > Ken Javor wrote: > >> General question for the group. >> >> I have recently purchased several different types of fluorescent >> replacements for incandescent bulbs. These would all appear to have >> electronic ballasts, because of size. They claim to meet FCC part 18, but >> there are disclaimers about moving the things if they cause rfi in the AM >> band. Well, they cause terrible rfi in the AM band, and in many cases they >> cannot be moved, because the radiation arises not just from the bulb itself, >> but from the power wiring. Just a few bulbs pollute a large home. And by >> pollution I don't just mean CE, but also RE from the power wires, so it >> isn't just a matter of plugging into a different branch. What is going on >> here? What is the point of enforcing conducted emissions on a power supply >> when lamps are allowed to emit? I understand that the cost of a filter >> compared to that of a power supply is a small fraction compared to the cost >> of a filter relative to one of these bulbs ($5- $10) but on the other hand >> these bulbs dissipate 5-15 Watts - it ought to be easier to filter these >> than a 200 Watt power supply. >> >> Comments? >> >> Ken Javor >> >> >> >> > > ---------------------------------------------------------------- > 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/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Ron Pickard: [email protected] > Scott Douglas [email protected] > > For policy questions, send mail to: > > Richard Nute: [email protected] > Jim Bacher: [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/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
