Pure Sine Wave UPSes for New Dell PCs

Hi!

Not that I'd do this but for my information could you run a
1500 watt heater plugged into the battery side of a 500
watt UPS.

Ah, you'd better not. If the UPS was of a standby design (meaning that
it only runs the load from its battery when the power is out or out of
tolerance) you would be fine right up to the point where the power
failed.

If you were lucky, the end result would just be a sudden shutdown with
the UPS complaining about an overload. However, I'm inclined to think
that the UPS will try to support the overload, maybe even do so for a
little while and then go poof. At that point you'd smell the acrid
odor of burnt silicon. (It's one of those few stenches that tells you
in no uncertain terms that something has gone terribly, terribly wrong
and may now be on fire.)

A UPS that supports its load continually from the inverter (providing
an additional layer of protection, as well as no switching delay)
should also shut down when overloaded--but I suspect that it too will
try and possibly go "boom".

William

On Fri, 16 Apr 2010 09:06:06 -0400, "Tom Lake"
wrote:


"Tom Lake" wrote in message ...

Indeed. Lately I seem to be the mug that people with ye olde APC
units seek out to verify they work before spending on refurbing the
battery department. One unit - a 1995 SmartUPS 2000XL - required AC
before it would boot, whereas the next series (1999) SmartUPS 2200XL
will do a cold start if you know the technique. Why they aren't ALL
cold-start-capable beats me.

Even though they can do it, it looks like APC still advises against it due to potential
damage to components.

Tom Lake

I hadn't seen that.

I was looking at an older manual, I guess. The current (no pun intended!)
manuals don't seem to have this warning. All they say is that, "Cold start
is not a normal condition"

That I have seen, and it isn't "normal" in client ops, but it is
fairly routine in servicing.

On Sat, 17 Apr 2010 09:23:49 +0800, who where wrote:

On Fri, 16 Apr 2010 09:06:06 -0400, "Tom Lake"
wrote:


"Tom Lake" wrote in message ...

Indeed. Lately I seem to be the mug that people with ye olde APC
units seek out to verify they work before spending on refurbing the
battery department. One unit - a 1995 SmartUPS 2000XL - required AC
before it would boot, whereas the next series (1999) SmartUPS 2200XL
will do a cold start if you know the technique. Why they aren't ALL
cold-start-capable beats me.

Even though they can do it, it looks like APC still advises against it due to potential
damage to components.

Tom Lake

I hadn't seen that.

I was looking at an older manual, I guess. The current (no pun intended!)
manuals don't seem to have this warning. All they say is that, "Cold start
is not a normal condition"

That I have seen, and it isn't "normal" in client ops, but it is
fairly routine in servicing.

I should point out here - for the benefit of the uninitiated - the
usual caveat:- "do not try this at home. The display you have seen
was performed by a trained professional under controlled conditions"

There is a real hazard involved when a UPS is fired up on battery with
NO grounding. Dangerous voltages can be present on battery terminals
as well as the (obvious) output loads - and even on their chassis.
The normal 3-pin AC cord provides safety grounding when connected. In
our workshop, cold starts are *only* performed with an auxiliary
grounding lead.