RE: Surge Suppressors on a UPS
From: Price, Ed Sent: Monday, June 02, 2003 8:19 AM To: 'EMC-PSTC List' Subject: Surge Suppressors on a UPS 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 I'm replying to my own post because, so far, my question has not really been answered. It HAS generated a really large volume of private emails expressing concern about things like what happens when you use a UPS to power equipment with built-in surge suppression. Or questions about just what are these switching event waveforms that a surge suppressor might want to suppress, and why should they be allowed to be applied to equipment without surge suppressors (equipment designed with the assumption that the UPS is protecting it from the public mains). It looks like racking and stacking a UPS, with a power distribution strip (the moral equivalent of an extension cord?) feeding a group of discrete electronics boxes (most of which have built-in filters and suppressors) is quite common. Yet UPS manufacturers seem to be saying that this bad practice and will even void the UPS warranty. So far, all comments have been from USERS of a UPS. I would like to hear from the other side, the UPS designers. (Privately if you must, but I would like to be able to later post unattributed answers.) Thanks again! Ed Ed Price ed.pr...@cubic.com WB6WSN 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
Re: Surge Suppressors on a UPS
David Heald hea...@symbol.com wrote on 06/02/2003 11:51:50 AM: 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. If the capacitance of MOVs is a problem, then the capacitance of the X caps and Y caps found in most power supplies would be an even bigger problem. Don Borowski Schweitzer Engineering Labs Pullman, WA This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
This is a multi-part message in MIME format. So much for extension cords. I assume the UPS manufacturer claims his product is unsuitable for use with all computer products containing surge suppressors. Bob Johnson ITE Safety Title: RE: Surge Suppressors on a UPS So much for extension cords. I assume the UPS manufacturer claims his product is unsuitable for use with all computer products containing surge suppressors. Bob Johnson ITE Safety attachment: Robert_Johnson.vcf
Re: Surge Suppressors on a UPS
Dear EMC-PSTC colleagues; I mentioned off-list to Ed Price that almost all of the UPS from Tripplite are in fact back up rather than uninterruptible; they perform a switch from conditioned line power to inverter power in the event of an AC main failure. This means that they may produce unknown phase/voltage transitions at the switch point, and could cause some big trouble if they are driving inductive loads or inductive/capacitive suppressors. If the inverters have a sufficiently non-sine output waveform, they could experience significant load effects from suppressors or line conditioners. I think they would be OK with passive MOV suppressors, but harmonics and spike voltages from inductive loads may cause more current flow than normal in the MOV's. They may also not be FCC EMC approved when the load is plugged in to an extension cord, which might be considered a rather large antenna! Barry Rowland Vancouver BC On Monday, June 2, 2003, at 01:45 PM, Cortland Richmond wrote: I don't believe there are any power quality requirements imposed on inverters except those specified by buyers (in the USA, anyway). You can still buy square-wave inverters, after all, and the modified sine wave could be called Chock Fulla Harmonic power. Harmful interference is a limitation, but not one I'd expect manufacturers to be eager to fix, except, perhaps, to refund the purchase price. (Who's fixing the zillion SP's plugged into our toys?) And that warranty opens a whole _barrel_ of worms. Does user equipment with an integral surge suppressor void the warranty? The consumer doesn't know it's there, either. I'd imagine state attorneys general would have things to say about implied warranty of serviceability, if this came to their attention in a sufficiently egregious way. Passengers would sure hesitate to get on a liner whose lifeboats were described so unconfidently. As for plugging all equipment directly onto the inverter, that's unrealistic. I install an inverter in or on the battery compartment, in accordance with manufacturer recommendations, to minimize DC voltage drop. The inverter is connected to an AC distribution panel (which includes surge suppressors and filters). Then equipment I want to run, analyzer, receivers, signal generators, whatever., plugs into that. An IEC line cord won't even _reach_ the battery compartment where the inverter is installed. And a UPS that generates transients enough to fire suppressors, transients from which users ARE FORBIDDEN TO PROTECT EQUIPMENT, seems to me one to avoid. Could be, such warranties will end up costing vendors more than they'd expected. Then too, a good corporate counsel would point to the hundreds of warranties honored in spite of extension cords and surge suppressors, and convince a trial judge that state implied warranty, and vendor's existing warranty performance, had voided those restrictions historically, and presently. Cortland --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Surge Suppressors on a UPS
Chris Maxwell wrote: Fred, Maybe you're right. Do UPSs protect against lightning surge? Your question resolves into two issues: 1) Marketing Hype 2) Reality 1) I have seen some marketing hype that says their UPS will do everything to protect your system and wash the windows while it is at it. I think we know BS when we read it. 2) The reality is lightning is called an Act of God for good reason. Many of the things that determine whether you are protected from a lightning strike depend on circumstances beyond your control like how far are you from the strike, how far are you from the mains, and how conductive is the ground you walk on. I think one of the better UPSs out there recognizes no one can guarantee protection from Act of God but they do offer a free insurance policy to replace your equipment if it fails due to a lightning strike when connected to their UPS. Now that's putting your money where your mouth is. Fred Townsend I know that they protect against low frequency, low magnitude voltage dips and surges. However, I'm unsure of their ability to protect against lightning surge. If the UPS is specified by its manufacturer to protect against lightning surge; then my question is moot. Even so, I would still wonder, does the UPS guarantee that the UPS and the equipment attached to it would survive the surge? Or does the UPS sacrifice itself in order to protect its load? If there is any question, I would seriously consider putting the surge protector in front of the UPS and protect the whole system. We must also consider the power availability angle. If the surge protector is in front of the UPS; then even if the surge protector sacrifices itself; or blows a fuse to protect the UPS from the surge; the UPS will still power all of the equipment attached to it from its battery. If the surge suppressor were after the UPS; then blowing a fuse or tripping the surge suppressor would prevent the UPS from powering its outputs. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
Chris Maxwell wrote: To me, this whole thread begs the question: Why not put the surge supressor in front of the UPS? A lot of us have relied on full-time UPS's to stop transients. But the bit about a UPS itself producing large enough ones to trigger suppressors, that is worrisome. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
Fred, Maybe you're right. Do UPSs protect against lightning surge? I know that they protect against low frequency, low magnitude voltage dips and surges. However, I'm unsure of their ability to protect against lightning surge. If the UPS is specified by its manufacturer to protect against lightning surge; then my question is moot. Even so, I would still wonder, does the UPS guarantee that the UPS and the equipment attached to it would survive the surge? Or does the UPS sacrifice itself in order to protect its load? If there is any question, I would seriously consider putting the surge protector in front of the UPS and protect the whole system. We must also consider the power availability angle. If the surge protector is in front of the UPS; then even if the surge protector sacrifices itself; or blows a fuse to protect the UPS from the surge; the UPS will still power all of the equipment attached to it from its battery. If the surge suppressor were after the UPS; then blowing a fuse or tripping the surge suppressor would prevent the UPS from powering its outputs. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
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
Re: Surge Suppressors on a UPS
I don't believe there are any power quality requirements imposed on inverters except those specified by buyers (in the USA, anyway). You can still buy square-wave inverters, after all, and the modified sine wave could be called Chock Fulla Harmonic power. Harmful interference is a limitation, but not one I'd expect manufacturers to be eager to fix, except, perhaps, to refund the purchase price. (Who's fixing the zillion SP's plugged into our toys?) And that warranty opens a whole _barrel_ of worms. Does user equipment with an integral surge suppressor void the warranty? The consumer doesn't know it's there, either. I'd imagine state attorneys general would have things to say about implied warranty of serviceability, if this came to their attention in a sufficiently egregious way. Passengers would sure hesitate to get on a liner whose lifeboats were described so unconfidently. As for plugging all equipment directly onto the inverter, that's unrealistic. I install an inverter in or on the battery compartment, in accordance with manufacturer recommendations, to minimize DC voltage drop. The inverter is connected to an AC distribution panel (which includes surge suppressors and filters). Then equipment I want to run, analyzer, receivers, signal generators, whatever., plugs into that. An IEC line cord won't even _reach_ the battery compartment where the inverter is installed. And a UPS that generates transients enough to fire suppressors, transients from which users ARE FORBIDDEN TO PROTECT EQUIPMENT, seems to me one to avoid. Could be, such warranties will end up costing vendors more than they'd expected. Then too, a good corporate counsel would point to the hundreds of warranties honored in spite of extension cords and surge suppressors, and convince a trial judge that state implied warranty, and vendor's existing warranty performance, had voided those restrictions historically, and presently. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Surge Suppressors on a UPS
I disagree. One assumes some degree of surge suppression since suppression is touted as a UPS feature. Therefore your question is moot. Fred Townsend Chris Maxwell wrote: To me, this whole thread begs the question: Why not put the surge supressor in front of the UPS? Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
To me, this whole thread begs the question: Why not put the surge supressor in front of the UPS? Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
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. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Surge Suppressors on a UPS
I read in !emc-pstc that michael.sundst...@nokia.com wrote (in 57a26d272f67a743952f6b4371b8f81101e42...@daebe007.americas.nokia.com) about 'Surge Suppressors on a UPS' on Mon, 2 Jun 2003: 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? I think you are right. The advice is a cop-out. A surge suppressor on the output of a UPS should, in theory, never be activated. But something outside the spec of the UPS, such as a close lighting strike, might activate it and perhaps damage the UPS. Banning extension cords (without surge suppressors) is bizarre and inexplicable. I see the leaden hand of the corporate attorney there. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Surge Suppressors on a UPS
Ed, I also hate it when I get ambushed. In the matter of the extension cord: I guess to lessen their liability they don't want any extra voltage drop from a cord? I also agree, why would I hook up a UPS that could fry my equipment with a switching event? When you find out let me know, as this sounds like something I need to know! Michael Sundstrom NOKIA TCC Dallas / EMC of: (972) 374-1462 cell: (817) 917-5021 amateur call: KB5UKT From: ext Price, Ed [mailto:ed.pr...@cubic.com] Sent: Monday, June 02, 2003 10:19 AM To: 'EMC-PSTC List' Subject: Surge Suppressors on a UPS 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
