mark@intek01.uucp (Mark McWiggins) (01/05/91)
rcd@ico.isc.com (Dick Dunn) writes: >mark@intek01.uucp (Mark McWiggins) writes: >> We recently had some power supplies fried by a Unison Unipower 600. >> We had too much of a load plugged into the circuit the UPS was plugged >> into, and instead of doing anything protective or rational like shutting >> itself down, it burned up the power supply on a PC and a modem ... >Can you tell anything about the failure mode? What did the UPS do that >caused the power supplies to fail? It seems unlikely that an overload on a >UPS would cause an overvoltage on the output. I've been trying to >postulate some other sort of failure (in which the nature of the power >supply on the attached device would play some part) - such as clipping in >the UPS output turning into garbage in the power supply. Gosh, I'm just a software guy ... 1/2 :) I was out of town when this happened, but one of our guys talked with Unison. He's working out of the office this week, so I don't know what details he got. >Is this UPS a sine-wave output type? Supposedly, yes. >> ...Unison is aware of the problem, but I don't know about any >> upgrade/swap policy. >Do they say anything about what to do to avoid it (other than the obvious >"don't overload the UPS":-), or what types of devices would be susceptible? >Is there a danger of damaging components beyond the power supplies in the >attached devices? I didn't hear any recommendations; my recommendation would be "ditch your Unison and get something else." I only have one data point, but nothing behind my power supplies (on Telebit modem and 386 clone) seems damaged. My NEC monitor had funny colors for a couple of days, but it now seems fine too. An analogy? The fire department coming around for an inspection, discovers that you're operating your fireplace without a screen, and burns your house down! -- Mark McWiggins Integration Technologies, Inc. (Intek) +1 206 455 9935 DISCLAIMER: I could be wrong ... 1400 112th Ave SE #202 Bellevue WA 98004 mark@intek.com Ask me about C++!