Dear Bob I thought very large numbers of commercial computers these days went into 'server farms' (sometimes called 'Internet Hotels' or 'Cisco Hotels') and these will almost certainly have a non-public LV supply.
I don't know enough about the process of creating IEC 61000-3-2 to comment on whether it is skewed, but I am led to believe that the convener of the WG that created it was for many years a senior person in the computer industry. Regards, Keith Armstrong In a message dated 25/01/02 12:16:15 GMT Standard Time, rehel...@mmm.com writes: > Subj:Re: EN 61000-3-2 applicability and let-outs > Date:25/01/02 12:16:15 GMT Standard Time > From: rehel...@mmm.com > Sender: owner-emc-p...@majordomo.ieee.org > Reply-to: <A HREF="mailto:rehel...@mmm.com";>rehel...@mmm.com</A> > To: cherryclo...@aol.com, emc-p...@majordomo.ieee.org > > > >I realise that none of the above give much comfort to manufacturers of > >domestic or consumer products, but maybe a computer manufacturer could > offer > >a version without PFC only for use in installations that have a dedicated > LV > >supply. > > No, the big problem is for manufacturers who make commercial and light > industrial equipment that are under > 16A and are connected to the public power mains. This is the majority of > commercial equipment. > > As was mentioned previously, the harmonic and flicker standards are > considered by many to be "skewed" > standards because they were heavily influenced by the power industry > virtually to the exclusion of all other > data and input. > > The issue is not whether harmonics and line votage variations are a > problem. The issue is to what extent they > are a problem. And until these standards become "unskewed" and all data is > weighed, these two "tainted" > standards will not be believeable. > > Bob Heller > 3M Product Safety, 76-1-01 > St. Paul, MN 55107-1208 > Tel: 651- 778-6336 > Fax: 651-778-6252 > > > > > ================================================================================ > > > CherryClough@ao > > l.com To: j...@jmwa.demon.co.uk > > cc: > emc-p...@majordomo.ieee.org > 01/24/2002 (bcc: Robert E. > Heller/US-Corporate/3M/US) > 11:58 AM Subject: EN 61000-3-2 > applicability and let-outs > Please respond to CherryClough > > > Dear John > I understand the following statements to be true. > Please make corrections / comments where necessary. > > 1) EN 61000-3-2 only applies to equipment consuming up to 16A/phase, and > there are no mandatory harmonic limits in the EU (yet) for higher-powered > equipment, other than what the power supplier might impose. > > So EN 61000-3-2 is optional for equipment consuming >16A/phase. > > 2) EN 61000-3-2 currently has a let-out for "professional equipment" that > consumes more than 1kW, so its application is optional for that category of > equipment too. > > This could exclude many of the larger products sold solely for commercial > and/or industrial use from EN 61000-3-2. > > (Maybe the combined air-conditioner / personal computer may not be such a > bad > idea if it gets consumption up above 1kW!). > > 3) The 'public low voltage supply' is a 4156/230V supply with more than one > consumer connected. Large plants or office building often take their power > at > MV (11kV or more) and transform their own LV supply with their own > distribution transformer - creating a 'private' low voltage supply > dedicated > for their own use. > > EN 61000-3-2 is optional for any equipment sold solely for use on such > dedicated low voltage supplies. > > Privately-generated LV supplies ditto. > > 4) My copy of EN 61000-3-2 has a paragraph at the end of its Scope section > that says: > "Special equipment, which is not widely used and is designed in such a way > that it is unable to comply with the requirements (limits), may be subject > to > installation restrictions. The supply authorities shall be notified as > authorization may be required before connection." > > So custom-made or low-volume manufactured equipment (even if under > 16A/phase) > does not have to comply with EN 61000-3-2, as long as their users check > with > their power suppliers that they are OK to be connected. > > Maybe they could agree to deal with any harmonic issues at site-level, by > installing an active harmonic cancellation unit. > > > Regards, Keith Armstrong > >
