Re: Re: External APC Batteries?

[ukha@xxxxxxxxxxx]

Quoting Andy Whitfield <andywhitfield2002@xxxxxxx>:

>
> I'm so tempted to reply with just a smiley!   ;-)
>
> But seriously......
> So often I tell people about the dangers of batteries Even a small
> 12v 7Ah battery has a short circuit current of up to
> 500 amps.  So if someone did short out the battery with, lets say,
> their metal watch strap, they could find the watch strap welded to
> their wrist bone!  (me resists temptation to put in a smiley)
>

Thinking back to the "batteries" that used to be in the old
Strowger
exchange at Great Yarmouth......

Each CELL was a tank about 4 foot x 4 foot x 4 foot. The circuit
breaker on the end of the battery rack was designed to trip at
something like 20,000 amps and had super strong springs to pull it
open fast enough to break the arc which would have occured. It then
had a hydralic damper so stop it before it hit the end stop or it
would have ripped itself off the rack due the the force involved.

If a spanner was dropped on the bus bars is wouldnt melt...... it woud
VAPOURISE !!!

How technology has changed over the years. Back then the exchange
would use virtually zero power in the early house when no one was on
the phone but thousands of amps during the morning peak. Even without
the generators the exchange could run for hours without power. Now
with electronic exhanges the peak power is a fraction of what it used
to be but power consumption is almost contant irrespective of traffic
meaning that standby generators are essential.

Getting back to the origianl topic..... Will the UPS's be able to be
fired up without mains power ?

I have a couple that cant be used if there is no mains input to start
them, when the mains fails the UPS takes over but it cant be started
without mains. Might need a cheap inverter to trick it into life
unless you leave it running continuouslywhich obviously reduces run
time.