Mailinglist Archive: opensuse (2496 mails)

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Re: [opensuse] UPS And Multiple Computers
  • From: James Knott <james.knott@xxxxxxxxxx>
  • Date: Mon, 01 Dec 2008 15:58:09 -0500
  • Message-id: <49344FE1.6060706@xxxxxxxxxx>
Per Jessen wrote:
Erland Moller wrote:

Don't forget that with a bigger/more expensive UPS, most of the time
you have the advantage of hot-swappable battery's and/or a bypass
function plus the ability to shut down more than one server if things
go wrong. Most of the small UPS's have to be shut-down to swap the
battery's. Furthermore with the big UPS's the battery voltage is
higher resulting in low amp's on the battery's resulting in longer

Erland, I think you're talking very large UPS'es here - I haven't seen
anything less than 25kVA with hot-swappable batteries. Bypass mode
yes, but hot-swappable batteries is another level.

And those would of course be the whole office kind of UPS, not the stick them under your desk so that you can kick them type. I have seen a lot of different types of UPS over the years, including some in an office where I used to work. On these, the incoming AC ran a motor, which turned an alternator & 8 ton flywheel. When the power died, a clutch would connect the shaft to a diesel engine. The flywheel started the diesel, while maintaining speed for the alternator. One disadvantage to this system, was the output power was slightly lower frequency than the input, which caused the real time clock in some computers to run slow. In that same building we also had some turbine & diesel standby (not UPS) power and a huge battery type UPS. There were also banks of batteries & rectifiers supplying about 7000 amps @ 48V for all the telecom gear. (There were other batteries supplying +-60V and 24V power) This was in a telecom central office that also housed the Air Canada reservation system and several other message switching computer systems. There were so many large batteries that some of the floors in that building had to be specially reinforced.

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