The plug-in UPS serves one primary function. It protects
data from power problems. It does not protect hardware. Did
you read the long list of exemptions attached to that
warranty? Good luck if you need to have that warranty
honored.

I have a UPS right here for 120 volt operation. To generate
(in battery backup mode) what is considered 120 volts, it
outputs two square waves of 200 volts with a 270 volt
transient between those square waves. This output could be
destructive to some appliances such as small electric motors.
However computers are so resilient that even this harsh UPS
output will not harm computers.

The plug-in UPS is for data protection. Computers already
(should) have internal protection which is why many UPSes do
not damage a computer.

David LeBrun wrote:
OK...this is getting a little too technical for me (I am by no means
an electrician) but I guess I understand the basic principles. I do
however find all these details interresting even though some of it is
way over my head.

I do have to agree that there are cheap UPS units and then there's
REALLY CHEAP units. I think that any "consumer" or "retail" UPS is
going to at least be cheap relative to any "industrial strength" unit
which probably means that the units I have are at least cheap. I have
one which (now that I really look at it) looks like nothing more than
a power bar with a battery in it. The other one is a big and heavy
metal box which has more guts in it judging by the soft hum that comes
from it during normal operation and not so soft hum when disconnected
from AC.

All I know is if anything were to happen to my equipment by these
things not doing what was advertised I would just have to cash in on
the warranties offered by the manufacturers and if this casualty
system were mine hooked up to one of my UPS units you can be sure
they'd be footing the bill to get the parts replaced.

Dave.