[kwlug-disc] UPS sized battery purchasing locally?

[unsolicited]

Sorry John, you've missed the point.

'pure sine wave' in ups' usually mean power live conditioned.

Most UPS', especially cheap ones, e.g. used to be APC Back-UPS vs 
Smart-UPS, straight pass through the mains (surge protected). It's only 
on battery power that you get conditioned power.

'pure sine' ups' typically also act as full time line conditioners as 
well, instead of having to also purchase a line conditioner.

Not just trim the tops and bottoms off, or bump, brownouts / blackouts, 
and otherwise pass it through, but actually condition all of the power, 
all of the time.

There was a time when such was considered pretty important for equipment 
longevity, and to assist in decreasing the frequency of stupid glitches 
within a computer. Ones slipping into zeroes, and vice versa. [I can 
only imagine the power inputs to a super-cooled Cray.]

I'm not sure I agree, with most consumer grade equipment today, which 
seem to not last long enough for any cumulative power effect to come 
into play before you have to replace a beastie anyways.

Let alone if you're just plugging a DC power brick into it.

'Better' power costs more, and there are tiers. Something to pay 
attention to (as in feature differential) when ups shopping, so you's 
knows what you're buying. (Caveat eptor.)

And is why I have typically preferred Tripp-Lite over APC, and been 
willing to pay a bit more for.

And is why I said what I did about APC, wrt $ for $ value.


On 14-06-01 07:02 PM, John Johnson wrote:
> On 2014-06-01 18:24, unsolicited wrote:
>> ... cause I wanted pure sine out ...
>
> While not questioning your requirements I will take this as a jumping
> off point for this discussion.
>
> The output of some UPSes is, as you noted, not a sine wave. For these
> types of UPSes the output s is generated by a rectangular pules in
> opposite polarities.
> The amplitude of the pulses is usually fixed. The width of the pulses
> are modified in a Pulse Width Modulated manner such that the resulting
> power curve approaches the nominal 110 Vac.
>
> Note, I said "power curve" as this implies both supply voltage and load
> current.
>
> The voltage and current are specified in RMS - Root Mean Square - while
> not mathematically exactly an "average" can be thought of as such.
>
> The nominal 100 Vac sometimes called 117 Vac or 120 Vac has a wide
> tolerance, ranging from about 90 Vac to something around 126 Vac.
> I would expect that UPSes are calibrated to supply their output at the
> low end of this range.
>
> For most equipment this synthesized ac voltage supply is perfectly OK.
> (Even for a "shaded-pole" AC motor. Personally, tested and verified.)
>
> Pure sine wave AC is important for some synchronous motors.
>
> jsquared
>
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