Date: Fri, 7 Jul 95 10:08:22 -0400 From: crtb@helix.nih.gov (Chuck Bacon) To: Chuck Robey <chuckr@Glue.umd.edu> Cc: freebsd-questions@freefall.cdrom.com Subject: Re: Using No-break Power Systems Message-ID: <9507071408.AA23340@helix.nih.gov>
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> My new apartment comes with full amenities, including (what seems to be) > daily short power interruptions, usually less than 1 minute in length. I'd > like to get no-break power, something like an APC power system, just for > the two system boxes (not the monitor, printer, etc.) Each system has a > 300 watt power supply, which I think is lightly loaded. I was wondering > if anyone who has experience with power (I don't) could give me a SWAG as > to the VA load I need to run to be able to allow for ignoring 1 minute > outages, and allowing 4 minutes extra for system auto-shutdown if it runs > longer? I found a Tripp-Lite model 450LAN at a surplus sale. Judging by the model name, I gather it's supposed to support LAN servers up to 450 VA. It was new, I think, but I got it for a great price for the time, $200. Today, you can find similar VA ratings for far less. I used it to support three AT&T 3B1s for a couple years, and it never failed. I've had it for about four years. Many times per month I can hear it bragging -- beep, beep -- about how it saved my hide :-) It's cheap; it takes a couple milliseconds (?) to switch from straight through to its own inverter, but modern PC power supplies will ride out quite a bit of outage, up to a quarter second easily. Also, it doesn't put out true sine wave, but a kind of square wave, which PCs generally like well enough. I've ridden through outages up to several minutes with my PC, modem, monitor and printer all smiling at me. Generally, I think UPSes tend to be rated for twenty minutes at their power rating. This means a 450 VA unit should support 300 watts for perhaps thirty minutes. To save money, I might be tempted to buy a unit with only a minute's worth of capacity, since outages in this area seem to last only a few secondS, but I don't know if anyone makes such a thing! Anyway, for the price nowadays, I'd suggest getting about 50% to 100% overcapacity, so you can hang other useless stuff on it like a TV. For brand name, I like this Tripp well enough; I'd go for a well-known name like Tripp, Best, APC and the like. > ----------------------------+----------------------------------------------- > Chuck Robey | Interests include any kind of voice or data > chuckr@eng.umd.edu | communications topic, C programming, and Unix. > 9120 Edmonston Ct #302 | > Greenbelt, MD 20770 | I run Journey2 (Freebsd 2.0) and n3lxx > (301) 220-2114 | (FreeBSD 1.1.5.1) and am I happy! > ----------------------------+----------------------------------------------- One man's experience; take it for just that :~) Chuck Bacon -- crtb@helix.nih.gov
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