Ed - You were asking about output power quality standards for UPS, and while I don't know the current correct answer (maybe someone from a UPS company can help us), here are 3 standards that all cover UPS performance:
1. EN50091-3 2. IEC62040-3 3. IEC 146-4 I suspect all 3 are the same document in different stages of life, or at least have the same basis. Hope this helps, Jim Eichner, P.Eng. Compliance Engineering Manager Xantrex Technology Inc. phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. From: David Heald [mailto:hea...@symbol.com] Sent: Monday, June 02, 2003 11:52 AM To: ed.pr...@cubic.com; emc-p...@majordomo.ieee.org Subject: Re: Surge Suppressors on a UPS Most UPS's use a stepped approximation of a sine wave when in battery mode. While most switching supplies don't care (and are the intended loads for these UPS's), surge suppressors can cause real issues - It has something to do with capacitive overload of the output circuits. And for the second question - there are huge variances in the output wave quality. The brand I am familiar with has both stepped approximation and true sine wave output models - the sine models being the expensive ones. The stepped approximation models are ideal for switching supplies, while the sine output models can handle all kinds of loads including motors (but a quick check says that they still can't use surge supressors - this one has me puzzled!) The UPS EMC standard is 50091-2 (or was it 92-1?), but I'm not sure how much help it may offer. Best Regards, Dave Heald >>> "Price, Ed" <ed.pr...@cubic.com> 06/02/03 11:18AM >>> Hi Group! Last Friday, I got ambushed in a meeting. I hate it when that happens! A question was asked about whether it's OK to put a surge suppressor on the output of a UPS that is supplying power to some expensive equipment. I opined that I didn't think it should be necessary, but that it also shouldn't hurt anything either. So then somebody asks me why all the UPS manufacturer's sites say not to use a surge suppressor. I expertly reply that gosh, I don't know, but I'll take a look. The next question nails me again. "Are there any standards for UPS output power quality?" Uh, well, I'll look into that too. Now, the market is light industrial, USA, but are there any applicable EN standards also? Just for some background, here's a typical entry from Tripp-Lite's FAQ list for UPS's (not to pick on Tripp-Lite; they just said it most succinctly of several sites I looked at): http://www.tripplite.com/support/faq/tech_ups.cfm Can I plug a surge suppressor or extension cord into my UPS? No. Using an extension cord will void your equipment coverage warranty, as all equipment must be plugged directly into the UPS. Tripp Lite does not recommend plugging a surge protector into a battery backup outlet of a UPS either as this can overload it. Also, when some UPS systems switch to battery power they will output a waveform that a surge suppressor may see as a surge and short-circuit the UPS. Again, this setup will void the equipment coverage warranty. Now this is getting to be a big can of worms! What do they mean by "some UPS"? Is there one kind that does, and another kind that doesn't; and how do you know which is which? And if some UPS will create a voltage transient (is that what they mean?) sufficient to trigger a surge suppressor, then why is it OK to let the UPS apply that transient to my "protected" equipment? All this talk about uninterrupted power isn't worth anything if the UPS kills my equipment when it switches to battery power mode. And who's fault is this? I mean, a surge suppressor is pretty dumb; it just sits there waiting for the voltage to go over a certain level and then it conducts. What's this about the surge suppressor "may see" something as a surge? That's saying the surge suppressor could mis-interpret the waveform it sees. If the surge suppressor is conducting, then I think the UPS has just done something very naughty. I also don't understand the prohibition of an extension cord. Maybe this is a legal issue, as I can't see any valid safety or regulation issues here. We regularly put a UPS in the bottom of a rack system, and then wire a stripline outlet set for the height of the rack. Isn't that the electrical equivalent of an extension cord? What am I missing? Thanks in advance! Ed Ed Price ed.pr...@cubic.com NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty ________________________________________________________________________ This email has been scanned for computer viruses. ________________________________________________________________________ This email has been scanned for computer viruses. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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