It's also useful to know what your product does under non operating conditions. A common fault is open neutral and can happen anywhere from the power cord to across town. This leaves your equipment in series with other unknown loads from phase to phase. This is not something you should expect to use as an operating point. Planning operation under such conditions would appropriately require a UPS. However knowing what your equipment does is good safety practice. It may trip overcurrent protection or just sit and malfunction, but you don't want it to catch fire. Running it at a few operating points between 0 and 416 V gives you an idea of how it will fail. This is not a failure mode tested by the product standards.
Bob Johnson ITE Safety <http://www.itesafety.com> David Cuthbert wrote: Brian, When I worked for a well-known instrumentation company our universal power line requirement was, if I remember correctly, 80 to 270 VAC. If one could achieve more it was good. I designed one that would reliably operate from 75 to 280 VAC. This covered 100 V Japan on up with margin. Our products were sometimes used in the field with generators and I believe the extra margin built in helped us avoid field complaints. Our off-line bulk capacitance, as well as the DC output capacitance was unusually large to allow for long line dropouts. Of course building in extra margin can raise the cost of design and manufacturing. In our case it was reflected in higher capacitor cost and lower power density. The upside was a slow but steady improvement in our reputation and the ability to continue to command a price premium for our products. Dave Cuthbert Senior Test Engineer NARTE Certified EMC Engineer Linear Technology Corporation *******************Internet e-mail Confidentiality Footer******************* This e-mail transmission, and any documents, files or previous e-mail messages attached to it may contain confidential information that is legally privileged. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are hereby notified that any disclosure, copying, distribution or use of any of the information contained in or attached to this transmission is STRICTLY PROHIBITED. If you have received this transmission in error, please immediately notify me by reply e-mail, or by telephone at (719) 593-1579, extension 261 and destroy the original transmission and its attachments without reading or saving in any manner. Thank you. ======================================================= From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Kunde, Brian Sent: Wednesday, November 08, 2006 7:15 AM To: emc-p...@ieee.org Subject: Worst Case AC Power Conditions Greetings, 1. Can anyone provide specifications for a "worst case" real world AC power line condition in which an apparatus is expected to operate properly in (pass/criteria A)? This would encompass a combination of harmonics, voltage variations, frequency variations, etc.. 2. Also, if anyone has a program for a California Instrument CTS system with a 5000ix power supply that could test for a "worst case" AC line condition, that would be helpful. I have heard that some companies have developed such a custom program to simulate poor power conditions >from different parts of the world. Such a program would operate with the the provided CIgui32 program. 3. Can anyone recommend an AC Power Line analyzer that we can just plug-in and it will analyze the AC power conditions at different customer locations? Then we could take the results and program our 5000ix power supply to simulate those conditions in our lab. The reason I'm asking is that from time to time we have experienced problems in the field due to with poor AC power line conditions at some customer locations even though we test and comply with the standard tests that are required for CE (surge, burst, dips, etc). We want to develop an internal test standard that will minimize problems in the field. Thank for any help or advice you can offer. The Other Brian. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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