"Pete C." wrote:



Huh? Did you read what I said?

Yes

You modify the UPS to limit it's charge
rate to your average consumption. It will not in any way increase your
peaks, it will eliminate them.

Unless 1:your charge period, exceeds 1 or more demand periods, or 2:
You DONT charge until a low usage period, you will get no benefit.

TYpically a UPS has the capability to support its load with no
charging, for 5-30 min. The charging current & kva have a high peak
value when starting a charge, and could easily make your peak charges
much worse, especially if you run out of charge during what is still
your peak period.



It has to be an online type UPS so that the inverter portion is 100%
duty cycle rated and the UPS has to be sized to handle your peak load.

What you are doing is storing power in the batteries during times of low
usage and then drawing the extra power from the batteries during peak
use.

Be current limiting the input section (AC-DC) you eliminate any peaks
from showing through to the utility meter, it will see the same peak
load (max charging current) regardless of what your true peak load is.

To do that your battery system would have to be SO over sized as to be
beyond all belief. Unless of course, you are willing to live with
periods of no power, and if that was OK you could just shut things off
in the first place.



The difference between your actual usage and the charging current
represents either a surplus in which case the batteries charge, or a
deficit in which case the batteries supply the additional power to the
DC bus that the current limited input section won't.

A simpler way to think of this would be a water tank. If you were
charged for water base on peak flow rate and not gallons used you would
install a large tank and a small feed line to it from your water
utility. Say the feed line only flows 5gpm. You can quite readily draw
down the tank at a 20gpm rate if you want without it having any effect
on the utility side. The water level in the tank will drop, but once
your peak use stops and you are drawing less than 5gpm the tank will
fill again.

A better analogy would be a 20 gal tank feeding at 5 gal per min, and
then wanting to take a 10 gal per min shower, while some one flushes
the toilet.

jk