Good day all, A while back I wrote about an electrically powered hydraulic pump that had horrible radiated emissions. This is a brief update on what was found:
First, all motors of the same type exhibited similar noise. Second, loading had some, but small effect on the noise. Temperature had little or no effect on the noise. The hydraulic pump was systematically inhibited until there were no moving parts: no effect. A second CE motor was used with similar results. In desperation the motor was bolted to the bench horizontally to begin looking into what could be happening and all noise ceased. It was rotated vertically and all noise returned. The motors, ALL motors including CE marked showed this effect. I don't have the paperwork on the motor, but I'm sure there was no EMC testing done since this was an induction motor. So, I'd like to make folks aware that INDUCTION motors are NOT necessarily noise free, and some evaluation should be made if you use them in anything other than horizontal. <http://o.aolcdn.com/cdn.webmail.aol.com/31844/images/common/space.gif> If anyone wants some of the graphs please let me know. If anyone has a cure for this, I'd be very interested. Sincerely, Derek Walton L F Research. - 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 <emc-p...@ieee.org> 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 <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
