Yes I am in the US so clearly I must have been mistaken. Seriously, when that business started in 1989 there were relatively few PCs in use there. "PC cubes" were scattered throughout the building that people could use on an as-needed basis. By 1995, every engineer's cube had a PC running all day long. It would have been interesting, in retrospect, to have taken line voltage oscillographs at representative locations as the PC density increased.
>From: John Woodgate <j...@jmwa.demon.co.uk> >To: emc-p...@majordomo.ieee.org >Subject: Re: Unity Power Factor >Date: Wed, Jan 29, 2003, 4:01 PM > > > I read in !emc-pstc that Ken Javor <ken.ja...@emccompliance.com> wrote > (in <0h9h00l4ovp...@mtaout02.icomcast.net>) about 'Unity Power Factor' > on Wed, 29 Jan 2003: > >>I noticed this several years ago at >>the office building I worked in at the time. My cube moved from one end of >>the building to another, and my computer wouldn't always start - it took >>several tries. I brought in a scope, and saw that the ac voltage waveform >>was flattened. It was more flattened at my new cube than at my old one. >>Clearly this is related to power supplies recharging filter caps at the peak >>of the ac waveform, and the relative distance from the building main breaker >>at the two different cubes. This is a power/crest factor issue, not >>directly a harmonic issue, although drawing current only near the peak of >>the waveform will definitely generate harmonics. > > Aren't you in the USA? If so, you must have imagined the peak- > flattening. I am assured by the US experts on SC77A/WG1 that this > phenomenon is unknown in USA, and the only effect of IEC/EN 61000-3-2 is > that it increases the prices of PCs dramatically and keeps US products > out of Europe. To which my answer is 'McEnroe!' (YCNBS!) > > At least, they argued that way for about 10 years. The present US chums > are far more sensible. Even so, 'peak flattening' rarely figures in > their vocabulary. > -- > Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk > Interested in professional sound reinforcement and distribution? Then go to > http://www.isce.org.uk > PLEASE do NOT copy news posts to me by E-MAIL! > > ------------------------------------------- > 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 > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
