gen set synchronizer

[m35 adam]

Hi, has any body used a gen synchronizer? I want to hook two 10 kw gens to it. I know I will get 20 kw but will I be able to get 440 volt 3 phase? Thanks, adam

 

[Suprman]

I believe you just need a paralleling cable to run the 2 gens together for 20kw. You will only get the 120-208 3 phase though. I have seen synchonizers I have a few kicking around. I believe they are designed for running 2 generators, so one can be shut down for maintenance or replaced without the load loosing power. I don't believe you can the gens in series for higher voltage though.

 

[m35 adam]

ok that makes sense. thanks.

 

[Triple Jim]

You'll need some method of synchronizing the two generators before connecting them together. If they're out of phase when you turn on the breaker on the 2nd generator, the huge current surge will trip the breaker immediately. Sewerzuk made a nice video about how to do it that you should be able to find here and/or on YouTube.

 

[m35 adam]

Just watched the video. Very helpful. I will up load pic of what I have. Thanks.

 

[Poccur]

A genset synchro can be as simple as an AC bulb that is connected between the phase 1 of each generator. When the engines are out of phase then there will be a voltage difference (up to 208v), current will flow and the bulb is lit. when the bulb goes out then the phases are 0v apart and the gens are in sync and can be joined. Now, that said there is more to it. You need a way to keep them both in sync or they will drift out of sync, for that there needs to be some kind of communication between the gens..
Look at Governors of America they make load share modules:
http://www.governors-america.com/product landing pages/generator#Load

Once you conquer that then the last step is to find a way bring the outputs from the paralleled units together so they can power loads that total their combined capacity.
Always remember parallel is not the answer to every situation. If you want it for power backup, to guarantee power, remember your combined loads cannot exceed the max for one gen alone. If you exceed that then if one gen stops the other immediately overloads and you are right back where you started with no backup power.

 

[Triple Jim]

When the engines are out of phase then there will be a voltage difference (up to 208v), current will flow and the bulb is lit.

Agreed, except when out of phase, two times the peak AC voltage is present across the bulb. With 120 volts ac (one phase of three in this case), the peak voltage in the sine wave is about 170 volts. When two generators are out of phase, there is 170x2 volts, or about 340 volts across the bulb when at its brightest.

 

[Guyfang]

So why do you want to run two 10 KW sets in parallel? Redundancy? Or more KW?

 

[Poccur]

With 120 volts ac (one phase of three in this case), the peak voltage in the sine wave is about 170 volts. When two generators are out of phase, there is 170x2 volts, or about 340 volts across the bulb when at its brightest.

You are quoting peak vs RMS...most voltmeters read RMS. (cheap ones read peak and convert to RMS)....I can accept 240v if they are 180 degrees out of phase

 

[Guyfang]

That's called good clean A/C to me!

 

[Poccur]

That's called good clean A/C to me!

So true, in Germany that is your phase to neutral voltage..you have a manly voltage and a not so good frequency..
Here in the colonies we have a not so good voltage with a great frequency (120V 60Hz) (Yes I know there is 240V in the US but that is formed by 2 x 120v, 180 degrees apart with a center tapped neutral whereas our European allies are 240V line to neutral)..

The perfect combo is 240V, 60Hz in the wall...well, Tesla thought so anyway...

 

[Guyfang]

When I was in AIT in Ft. Belvoir, Va., we had an all day class on this subject. Actually, we get somewhere between 230 and 240 volts Phase to Neutral. We still say 220 volt here, even though it has been long 240 volts. And phase to phase is still called 380 volts. Even in the trade schools. Old habits die hard.

And of course, almost every home here has three phase to the house, and back home, two phases.