alt.energy.homepower

On Fri, 07 Sep 2007 04:45:39 -0000, philkryder < @ > wrote:


>
>wow - one of those - yeah, it's easier than you might think
>situations.

Yep. A philosophy in life that has served me well is, barrel right in and try it. If
it works, great. If not, backtrack and figure out why. There are a few areas of
exceptions, of course. Explosives, very high voltage and highly radioactive
materials, for instance.

>
>So....
>That's it - a double ended cord...

That's all it takes. I've installed breakers and a variety of outlets on my
generators

/Generator/Quiet_pack_55G/

so syncing is just a matter of flipping the breaker at the right time. It'd take a
little more coordination to jab a plug into an outlet at the correct instant but it
could be done.

>
>What would it take to make a "semi automatic" product to do this?
>
>Say a switch controlled by when the two units were in phase.

It's called an auto-sync relay. In the trade, such gadgets are referred to as
"relays" even though they're now solid state. Originally it was an electromechanical
gadget.

The simplest one generates an output when the two phases are within a pre-determined
phase angle. In TVA when I worked there, that angle was typically +- 5 degrees for
main plant generators. That let the operator get the speeds almost the same and then
just twist the "close" handle on the breaker. When the two drifted to within that
window the breaker closed.

Modern microprocessor relays have the ability to look at closing rate and inhibit the
breaker closing if the rate is too fast. IOW, if the generators are at different
speeds and the phases are rotating past each other. They also have time delays,
anticipation capabilities and even the ability to generate a rate signal to go to the
governor. The latter allows completely automatic syncing, no operator involved.

For small machines like we're talking about, only the simplest relay would be
necessary. The operator would have to manually manipulate the governor to sync the
speeds and then the phases. The relay would simply close the paralleling contactor
when the phase difference was within the window.

For a one-off project like we've been discussing, I think that I'd take a look at
some of the low end PLC (programmable logic controllers) These can be had in the
$100-200 range. It should be easy enough to hook each phase to an analog input and
write the logic to generate an output when the difference between them is zero.

John
--
John De Armond
See my website for my current email address

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