Date: Sat, 15 Nov 1997 15:11:51 -0500 (EST) From: Bill Vermillion <bill@bilver.oau.org> To: freebsd-isp@freebsd.org Subject: Re: Power Message-ID: <199711152011.PAA27444@bilver.oau.org> In-Reply-To: <Pine.BSF.3.95q.971115130536.14527A-100000@wopr.inetu.net> from Dev Chanchani at "Nov 15, 97 01:13:36 pm"
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Recently Dev Chanchani said: > We had an extended power outage last night. After realizing that our UPS's > would not keep our network up for the black-out, I ran to sears with a > credit card and bought a Craftsman generator. > > My lesson in power began :) ... > We have our servers, switches and routers plugged into APS UPS's (600's > and 650's). The UPS's are plugged into surge protectors. The surge > protectors are plugged into 15 AMP 12 guage 100 ft extension coards. Typically you should run the UPS'es directly from the AC and not through a surge protector. That's an awfully long run for extension cords. You'd be better off getting the building wired correctly. We > ran the extension cords (took them out of the wall) and plugged them into > the generator. The 650 UPS could not take it, it was flipping between > generator power and UPS power every second. So... my questions are as > follows: > 1. Can you plug a UPS -> Surge protector -> generator I'd forget the Surge protector in the middle. > 2. Are there any specifics I should look for when planning the power setup > of new servers and racks. Make sure real power is delivered as close as possible to the servers and the UPS. > 3. How much output does a genarator need per server (as a rule of thumb)? I haven't seen chart like that recently. Best systems had some extensive charts/recommendations. They have units with extra battery packs, up through units with small to large generator systems. > 4. Was the UPS switching from internal power to external power because the > generator power was fluctuating, not enough power, etc? You probably had poor regulation on the generator. Years ago when I worked in broadcast, we'd go to emergenecy power for 1 hour once each week to make sure things were OK. The generator there was a V8 Ford and put out about 10KW. That was some of the most miserable power I've seen. It had a hard time keeping 60cyles, and the clocks would be off by about 5 minutes at the end of an hour. You need to investigate generators that are designed for this, not the generators used for emergency lighting/camping. > If anyone has experience with this type of stuff, any help and information > would be greatly appreciated. Here's a neat way to get cheap UPSes - if you're lucky. The place I do some work for has a hardware scrounger person - he loves bargains. He frequents local auction, and surplus sales. About 3 months ago he paid $300 for a UPS with no batteries - and we started looking for batteries - about $1500 - but not bad for a 30,000Watt Leibert. Three weeks ago he picked up a 50,000 WATT Leibert for $500 - that comes out to 1 cent/watt. I figure we will get about 4 days minimum (more if we watch it) which will keep us up for most outages. The ISP's in Miami were down for about 3 days when Andrew came through. Here in Central Florida I was without power in my house for 3.5 days after a storm decided to put all the trees it could find on power lines. (we had to rent a truck to move the UPS - it weighed about 2000 pounds so it won't help if you're not on a ground floor). But for starters keep the surge suppresors out of the lines. The UPS takes care of that.
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