Re: killed my computer

On 2008-12-03, jk <klessig@xxxxxxxxxxxxxx> wrote:
Larry Jaques <novalidaddress@di\/ersify.com> wrote:


You 'splain me, Tawmy? (No info was found online during a quick
googling for it.)

I've always had passives and they've worked fine. Who makes actives
and what's the price differential?

WHat he defines as an "active" UPS is more commonly referred to as a
"double conversion" ups.

In a double conversion UPS all of the power is converted to DC, to
feed the DC bus and charge the batteries. THe DC is then turned into
(via an inverter) AC that is completely separate from your AC line.
When your input goes away, you just continue , but start discharging
your battery.


THe other type of ups, feeds input power straight out to the load, and
also charges a battery. WHen it senses a power problem, it starts the
inverter and then uses a relay to swap the output to it. Not a big
deal if the problem is a slow rise or fall in the voltage. But a
surge, or a total outage,[or other high speed events] which travel at
effectively the speed of light, reach your power supply before the
relay can do any thing about them.

Well ... there is a third type, exemplified by the Best Power
Systems FERRUPS which I have on several computers.

These bring the power in through a ferroresonant constant
voltage transformer (like the Sola ones) with some extra windings. The
line power is also used (separately) to maintain the charge in the
battery or batteries (one of mine -- a 2KVA one -- uses four *heavy*
12V gel batteries in series). The ferroresonant transformer does an
excellent job of protecting the load from surges and such, as well as
keeping the systems happy during brownouts.

When the power goes away, those extra windings are driven by the
inverter to maintain the voltage. There are no relays involved, and
switchover is fast enough so the load doesn't have a chance to notice
it.

These every so many hours will switch on the inverter to verify
the state of the batteries, and then switch it back off. Ever so many
days it will do a "conditioning" charge cycle on the batteries.

Best Power Systems is long gone -- but their products still show
up on eBay -- sometimes for very good prices -- so I have three of them,
one powering a two racks full of computers, and the other two powering
two Sun Blade 2000 computers, with the larger one also powering a
seven-drive tray of Fibre Channel drives running as a RAID assembly.
(The racked computers also have two such trays running.)

Enjoy,
DoN.

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