inverter overload (was transformer inrush) [RE-wrenches]

[sunwise]

Kirk:

How will you :sense" the current?

William Miller

Greetings again,

In the case of the well pump, when the pressure switch comes on to
provide power to the well pump it also powers up the coil on the 30amp
relay.  The effluent pump's supply is wired through the normally closed
contact on that relay.  Make sure you have a working tank alarm in case
someone leaves a faucet running, although the well pump would still
likely cycle and allow the effluent pump to run periodically.  You could
add another relay pulled in by the tank alarm that drops the well pump
if the tank alarm comes on as well, but probably not an issue.

I wouldn't worry about the two refrigerators until you try dropping the
well pump and effluent pump off the critical loads panel.  There it is
just a 240 vac 2p2t relay energized by the same power that goes to each
pump.  You wire the utility power to the NO and the inverter to the NC
with the pump on the commons.  If frequent power outages, you may want
to add a second pressure switch with settings just below the main
pressure switch's settings.  Wire the primary side of the "T-240"
transformer through that switch so the windings aren't a phantom load
all day.  Best to parallel the two sets of contacts in the pressure
switch as you'll be switching higher current at the 120 volt side of
that transformer. 

If you were going to do the frig, you wire into the little black box on
top of the master frig compressor so the 120 vac relay pulls in when the
compressor comes on.  The slave frig is wired through the NC contact
which opens when the master comes on.  Problem here is the auto defrost
is probably a bigger load and this set up won't get it.  If there was a
chest freezer in the house make it the master, as they are not typically
auto defrost and don't run very often.  All that said, the compressor is
usually less than 200 watts and no big deal.

I do something sorta similar with my frig.  I have a small 15 amp plug
in relay that pulls in to power up a power strip on the side of the
frig.  I plug all my cordless tool chargers, electric toothbrush, etc
into the power strip.  They get enough charge when the compressor is
running and then they aren't a phantom load keeping my inverter awake
all day.  Plug an old electric, dial type clock into it and get run-time
data on the frig as well.

Kurt Nelson

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