Hi Folks I completely agree with CC.
In order to avoid rating plate non-compliance with the marking requirements of safety standards, and to allow for unit variations and product upgrades everyone (well - almost everyone!) allows a good margin for error on the rated current/watts/VA markings. Thus a unit with a 0.6A actual consumption can easily carry a 1A marking. This can lead to horrendous over-estimates of the power consumption of a system if all the marked ratings are added up, especially if then used for other purposes, e.g. air conditioning cooling requirements (have you ever wondered/realised why many air-conditioned computer equipment rooms are so cold? - The designers guestimated, based on the total marked ratings, and then added a further margin "just in case"!) Real world measurements are the only way to get true answers - and use a good digital power analyser to measure V, A, VA, W & PF individually and collectively at the same time. John Allen Thales Defence Ltd (was Thompson Racal Defence Ltd) Bracknell, UK -----Original Message----- From: Colgan, Chris [mailto:[email protected]] Sent: 10 January 2001 09:28 To: Newsgroup (E-mail) Subject: RE: power factor Ratings plates can be terribly ambiguous. Although you can be sure that the VDU does not draw more than 1,5A (maybe plus 10% depending on which standard it was approved to) it may draw considerably less. Current ratings can range from slightly pessimistic to completely misleading. The only sure way to find out its power consumption is to measure it. Regards Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:[email protected] * http://www.tagmclarenaudio.com > -----Original Message----- > From: Fee John [SMTP:[email protected]] > Sent: 09 January 2001 16:58 > To: Newsgroup (E-mail) > Subject: FW: power factor > > > > > John Fee > NETC, Enterprise Ireland > Glasnevin, Dublin 9 > Ireland > Phone +353 1 8082214 > Fax +353 1 8370705 > E-mail [email protected] > > -----Original Message----- > From: Fee John > Sent: 09 January 2001 14:49 > To: '[email protected]' > Subject: power factor > > > Hi everyone. > > Would anyone be able to help with the following question I received from a > friend? > > I have a question : > Can you tell me the typical power consumption of a desktop > VDU. For example a Sun workstation VDU rating plate indicates > 220-230 V 1.5A. Rather than assume or guess a power factor > value, what would the power reading (Watts) be approximately > at 220V for nornal operation ? What power factor value > would you attribute to a modern desktop VDU ? > > > Regards, > > Jonathan. > > John Fee > NETC, Enterprise Ireland > Glasnevin, Dublin 9 > Ireland > Phone +353 1 8082214 > Fax +353 1 8370705 > E-mail [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] > ************************************************************** Please visit us at www.tagmclarenaudio.com ************************************************************** The contents of this E-mail are confidential and for the exclusive use of the intended recipient. If you receive this E-mail in error, please delete it from your system immediately and notify us either by E-mail, telephone or fax. You should not copy, forward or otherwise disclose the content of the E-mail. TAG McLaren Audio Ltd The Summit, 11 Latham Road Huntingdon, Cambs, PE29 6ZU Telephone : 01480 415600 (+44 1480 415600) Facsimile : 01480 52159 (+44 1480 52159) ************************************************************** Please visit us at www.tagmclarenaudio.com ************************************************************** ------------------------------------------- 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]
