Dear Ghery There is plenty of evidence, for harmonic problems, especially in large cities and large office buildings.
For example, an electricity supply engineer told me that in the financial district in London there are buildings where they cannot fit any power factor correction capacitors to the fluorescent luminaires - because they fail within days due to the waveform distortion caused by harmonic currents. So they have buildings drawing 100's of kA of lighting current at a low power factor (< 0.6 I understand). I also understand they have overheating problems with cables under the Thames connecting the two halves of London, due to harmonic currents. In the early 90's I spoke with a USA-based consultant who told me about a number of problems (e.g. completely burnt-out neutral cables) he had seen in buildings in the US where they had installed lots of single-phase equipment. 'Banana Skin' No. 102 in the EMC + Compliance journal, Oct 2000 (read it in the archives at www.compliance-club.com) describes harmonic overheating problems with low-voltage lighting installations in hotels and public buildings that has Fane Murray, a lighting consultant in the UK, very concerned indeed. I understand that the power distribution in the USA is generally less susceptible to waveform distortion than in Europe, nevertheless I understand that the US has its own harmonics problems – Mathieu van den Bergh, of Computer and Networking Services Inc., California said in August 2000: a) for many years the US has had IEEE-Std-519 which has recommendations for harmonic limits which are not much different from IEC 61000-3-2; b) the US lighting industry has voluntarily implemented ANSI harmonics standards for fluorescent lamp ballasts that are more stringent than IEC 61000-3-2, as the direct result of serious harmonics problems in large office buildings; c) the US Government has issued several large scale procurement requisitions for Information Technology that included far more stringent harmonics requirements than those in IEC 61000-3-2. Time does not permit me to go through my files to provide a longer list of real-life problems with harmonics. Regards, Keith Armstrong In a message dated 21/01/02 23:54:36 GMT Standard Time, ghery.pet...@intel.com writes: > Subj:RE: EN 61000-3-3 compliant heater controller > Date:21/01/02 23:54:36 GMT Standard Time > From: ghery.pet...@intel.com (Pettit, Ghery) > Sender: owner-emc-p...@majordomo.ieee.org > Reply-to: <A HREF="mailto:ghery.pet...@intel.com";>ghery.pet...@intel.com</A> > (Pettit, Ghery) > To: j...@jmwa.demon.co.uk ('John Woodgate'), emc-p...@majordomo.ieee.org > > So rather than educating the public on the cause of flicker, we get saddled > with a useless design requirement. Typical bureaucracy - don't fix the > problem, make it LOOK like you're doing something, at someone else's > expense. Just like the harmonics standard - fix a problem that doesn't > exist. > > Ghery Pettit
