Re: UPS waveform question for SUN servers

On Dec 16, 2:06 pm, JJ <j...@xxxxxxxxxxx> wrote:
I've been somewhat ignorant about UPSs.  It was just recently that I
discovered that the main difference between the two UPSs we have is
that one produces a true sine wave (APC smart-UPS), while the other
(which was cheaper but with a higher VA rating) produces a stepped
approximation (APC smart-UPS SC).
...
My real question is, do these computers (Blade 1k and Blade 2k) really
need a true sine wave of current from the UPS, or is a stepped
approximation good enough (especially for the short periods of time
they would be running off of the UPS)?  

Output from a computer grade UPS (your cheapest ones) is also called
stepped sine wave or modified sine wave. For example, the output from
a 120 volt UPS in battery backup mode is two 200 volts square waves
with a spike of up to 270 volts between those square waves. That
output (even the spike) must not be destructive to any minimally
acceptable computer. Industrry standards for computer power supplies
make that apparent. So why spend maybe five or ten times more money
for the 'so called' pure sine wave?

When a UPS is installed for serious purposes, its battery typically
lasts something less than 20 years. But plug-in UPSes are made as
cheap as possible. Often its battery lasts only three years. A
replacement battery may cost as much as an entire new UPS.

A cheap UPS has only one function: to maintain power so that data is
not lost. The typical cheap UPS can output power so 'dirty' as to be
harmful to small electric motors and power strip protectors. But this
power must never harm a computer. Also called a computer grade UPS.
.

Relevant Pages

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