... > The 240V countires agreed, but never changed their nominals, as this > would have involved serious changes to their power generation equipment. > ...
Hi George and All! The statement quoted above raises some doubts in me. Since 1983 the nominal voltage of existing 220/380V and 240/415V systems (should) have been evolving towards the value of 230/400V recommended by IEC (600)38 "IEC standard voltages". The transition period will (should?) end by the year 2003. During this period, as a first step, the electricity supply authorities of countries with 220/380V systems (e.g., Germany, Italy, etc.) (should) have been bringing their voltages within the range 230/400V +6%, -10% and those of countries with 240/415V systems (e.g., UK) (should) have been bringing the voltage within the range 230/400V +10%,-6%. At the end of the transition period (2003), the tolerance of 230/400V ±10% (i.e., a range from 207V to 253V for the 230V value) should be achieved. A reduction of this range to 230/400V ±6% (i.e., a range from 216V to 243V for the 230V value) was (is?) under consideration. AFAIK the distribution transformers in countries with nominal voltage 380/220 VAC used to have 400 V as no-load secondary voltage. Analogously 433 VAC used to be the no-load secondary voltage of the distribution transformers in countries with nominal voltage 415/240 VAC. (Am I right?) The new nominal voltage of 400 VAC may be achieved by means of distribution transformers with a no-load secondary voltage of 410 VAC. (A distribution transformer with 410 VAC no-load secondary voltage provides about 400 VAC at full load with a lagging power factor between 0.85 and 0.90.) No-load 410 VAC may be well approximated also by "old" distribution transformers provided that they be provided with voltage taps +/- 2 x 2.5%. By adopting the +2.5% tap, the no-load secondary voltage of a "continental" transformer would increase from 400 VAC to 410 V. Analogously, by adopting the -2 x 2.5% (= -5%) tap, the no-load secondary voltage of a "UK" transformer would decrease from 433 VAC to about 411 V. Not by chance, CENELEC HD 538.1 S1/A1 - issued in March 1995 - states that "For the low-voltage winding" the "Rated voltage 410 V is suitable for new transformers in the intermediary steps of bringing low-voltage systems, originally at 380 V, within the range 400 V +6%/-10%". All this should have allowed all the European utilities to switch to the nominal 400 VAC standardized by IEC (600)38 either by adopting new distribution transformers conforming to CENELEC HD 538.1 S1/A1 or by adopting the above-mentioned voltage taps of their "old" transformers (provided the "old" transformers were provided with such taps). My doubts: 1. Why should the power generation equipment be affected by the adoption of 400 VAC? The change affects only the distribution transformers. Conversely the alternators are electrically very distant from the low-voltage customers and many voltage levels exist in between (generation, transmission, primary distribution, secondary distribution). 2. However why are the European utilities still so late in adopting 400 VAC? Who has any replies or comments? TIA Canio Dichirico European Southern Observatory Technical Division - Electronic Systems Department Karl-Schwarzschild-Str. 2 D-85748 Garching bei München Tel./Fax +49-89-3200 6500 Fax +49-89-3200 6694 email: [email protected] website: www.eso.org ----- Original Message ----- From: <[email protected]> To: <[email protected]> Cc: <[email protected]> Sent: Friday, February 02, 2001 20:30 Subject: Re: 230 Vac or 240 Vac? > > David, > > Here is my understanding based on an earlier discussion on this forum > and some of our business experiences. The agreement amongst many high > volt countries was on a 220-240V range. This implies a 230V nominal. > The 240V countires agreed, but never changed their nominals, as this > would have involved serious changes to their power generation equipment. > > Their reasoning was that a product rated at 220-240V is required under > IEC 60950 and like standards to be tested up to 6% over rated voltage, > i.e. a max of 254V. They assumed they could deliver power to the end > users within this range without changing their nominals. > > I'm beginning to doubt this assumption as we have had numerous reports > of our direct plug-in external power supplies running "hot" in two > geographies only, viz. the U.K. and Australia/New Zealand. Since we > have specified and tested up to 254V without problems, it is my belief > that the end users may be seeing over 254V on low periods of the day. > High usage periods result in more IR drop along the transmission paths, > and reduce the end voltage. > > This is just my opinion based on my experiences. > > George Alspaugh > Lexmark International Inc. > > > > > gelfand%[email protected] on 02/02/2001 10:56:22 AM > > Please respond to gelfand%[email protected] > > To: emc-pstc%[email protected] > cc: (bcc: George Alspaugh/Lex/Lexmark) > Subject: 230 Vac or 240 Vac? > > > > > Group, > > I seem to remember that Australia was changing their nominal voltage from 240 to > 230 V. Is this true? Are there other countries that have nominal voltages of > 240 V? I want to determine the maximum voltage for leakage current tests. > > Best regards, > > David. > > David Gelfand > Regulatory Approvals > Memotec Communications Inc. > Montreal Canada > > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: [email protected] > Michael Garretson: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
