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TWayne TWayne is offline
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Default Generator Power Shedding?

Pete wrote:

The Daring Dufas wrote:

Pete C. wrote:
The Daring Dufas wrote:
Ron Hardin wrote:
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.

http://www.functionaldevices.com/

http://tinyurl.com/5fuhg8

http://www.johnstonesupply.com/corp/Default.aspx

TDD

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 larger generator.


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.

TDD


Bull.

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
generator.

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 generator.


You're making it even more obvious what you don't know. Because you
don't know how to do something is no reason for you to attack others who
might be on the right track. Your concepts of how relays can work is in
bad need of help also. When you have nothing worthwhile to say, that's
what you should say: Nothing.