Is there a power-strip like device for use with portable
generators that turns off outlets when other outlets are using
a certain number of watts?
Like you'd want to turn off the refrigerator while the sump pump
cycles, to keep the total watts under say 2000; but mostly the
refrigerator stays on.
You can easily build your own if you're handy
with electrical modules. You won't have to
build any circuit boards because the parts
are available off the shelf. You can use a
current sensor and relay module manufactured
by Functional Devices, Inc which are sold at
many HVAC supply houses like Johnstone Supply.
Generator load management is a bit more complicated than that and simply
dropping lower priority loads when higher priority ones come on won't
work properly and could potentially damage items.
A proper load management setup needs a controller with some smarts, and
monitoring connections to things like sump pump switches, thermostats,
etc. so that it can tell when an item needs to run, even though it is
not currently powered. This type of control just isn't practical on a
small scale where the cost of the control would exceed the cost of a
yes but you do NOT want to turn off power to the fridge and then turn
it back on a few seconds later... the compressor will not be able to
re-start when the pressure is already built up in the system... it
will cycle on overload for a few minutes until the pressure dies
down. That is OK it won't BREAK anything right away but it does
stress the overload switch and compressor and is not the best thing to
do for long term.
So what's a 555 timer cost???
The general idea isn't difficult to implement w/ anybody who's got some
Radio Shack-type skills and interest.
It's probably there are some moderately inexpensive devices readily
available altho I've not done any looking. Undoubtedly there will be
info on the alternate-energy and living-off-grid and generator groups...
Have you ever heard of an anti short cycle timer.
It's a little module available at the same HVAC
supply house as the other parts. The things are
very inexpensive and I install them on AC units
all the time. It would be easy to add it to the
setup. Do I have to design the darn thing now?
Nope, the end result of such simplicity will just be an intermittently
overloaded generator, devices damaged by short cycling, floods because
the sump pump didn't get enough run time, etc. Proper load management
requires the smarts along with sensing to hold off providing power to
item Y until item X has completed it's cycle.
Baloney. Get a list of the various loads, the wattage draw of each and
starting surge where applicable, and then you try to work out your logic
chart for this application to determine which loads can be allowed to
come online in what combinations without overloading the generator.
Be sure to account for devices that present more than one level of load
such as a refrigerator (cool vs. defrost) and devices that could be
damaged by repeatedly cutting their operation short, such as those with
cool down cycles. Be sure your current monitoring reacts fast enough to
drop excess loads when a new load comes online with it's peak starting
current, before you stall a regular generator, or put an inverter
generator into overload protect shutdown.
Welll, I'll tell ya what; I didn't say the less than educated would
understand it. You would need a decent background to fully understand
it, even though the implementation is rather straight forward and
do-able by most anyone who can minimally read a schematic.
If I didn't have experience in the area, I would not have offered this
up. This however is likely my last response to the likes of trolls like
you; you're not worth the effort, time or ether. You obviously have no
grasp of the actual requiremnts so should shut up or offer instances
where you can be showh where you're wrong or right. Then at least you
would learn something. Ignorance truly can be bliss.
Yes, your ignorance sure must be blissful. The two of you trolls have
yet to give a single bit of factual data, nor have you addressed any of
the detailed issues I've mentioned. You should stick to wiring holiday
2,000 freaking watts! Geez! A very simple automatic switch
can do the trick for the guy. A current sensor, a timer
and a relay could make up a simple load control for the
man's generator to drop the refrigerator when the sump
pump kicks in. No micro-controller or fancy PLC needed.
If it involved 10,000 to 150,000 watts or more, I could
understand the need for more finesse. For a generator I
can pick up with one hand, nope, nope, nope.
With a generator as small as 2KW, the generator will probably stall
before you can shed the new load, and even if it doesn't it will bog
down badly causing low voltage and low frequency issues. If it's an
inverter based unit like an EU2000i it will just go into protect mode
and you will loose output until you manually stop and restart the
You think it sounds simple, but you've clearly never done load
management, nor have you thought through the details of the problem.
With a generator that small, the OPs safest and simplest solution is to
swap power cords around manually.
Relay logic as you noted in another post would be a bloody mess for this
since you have to know the load of each of the controlled outputs and
determine the allowable combinations that will not overload the
Good Lord, you're making it more complicated than
it needs to be. I could do it quite simply with
all off the shelf inexpensive timers and relays.
I have had a smidgen of experience with little
Cats and tiny little 16 cylinder EMD generators
putting out a minuscule 4,160 volts and enough
current to melt the proverbial crowbar. Don't over
engineer the golly gosh darn thingy itty bitty
generator, it's not an APU on the space shuttle.
I guess all those 5 to 40kw generators I've installed
and maintained for homes and business have left me
with a substantial dearth of knowledge when it comes
to electrical systems. Should I walk you through
the simple steps that would address all your dire
concerns for blowing up the itty bitty power plant?
Of course, the simplest thing is as you say is to
switch cords but if he's anything like all of us
lazy humans who love to take advantage of existing
technology for the sake of convenience, he wants
Whoop-dee-doo, you still haven't covered the actual issues, particularly
with the probability of an inverter based generator give the OPs mention
of 2KW, and the fact that as soon as the new load came online the
inverter would trip out on overload before your relay could shed other
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