A different question about power supplies

My situation is that AC power is so unreliable out here that I have
UPS units on everything electronic that I need to keep running (TV,
Satellite, DVR, WISP, both computers). However, "some" of the newer
power supplies, apparently the very efficient ones, won't tolerate the
square wave that the UPS outputs when we have a power failure, so the
computer just shuts down, ie. acts as if there were no UPS there. How
can one determine if a power supply will operate with a square wave
input?

Charlie Hoffpauir wrote:
My situation is that AC power is so unreliable out here that I have
UPS units on everything electronic that I need to keep running (TV,
Satellite, DVR, WISP, both computers). However, "some" of the newer
power supplies, apparently the very efficient ones, won't tolerate the
square wave that the UPS outputs when we have a power failure, so the
computer just shuts down, ie. acts as if there were no UPS there. How
can one determine if a power supply will operate with a square wave
input?

There is no answer for this.

Power supplies are not generally specified in terms
of their Active PFC tolerance for irregular voltage
waveforms.

An SPS UPS (standby type), does not interfere
with the electricity, when AC wall power is available.
It's when the power goes off, the UPS switches
to battery, turns on its modified step inverter
output, that the problem arises. As now the
voltage waveform isn't the right shape.

Using a UPS with a "pure sine wave" output may help.

This is an example of a pure sine, for $130. I don't
know what your hold-up time requirements are, but
that'll support at least one computer. This one is
even line-interactive, which means it will help
you in brownout conditions. (You'd need to see a
spec sheet, to see whether the spec is good
enough or not. Or whether it's an AVR in name only.)

http://www.newegg.com/Product/Produc...82E16842102131

Paul