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jacquesl 13th January 2007 06:45 PM

Synchronizing multiple generators -AC of courses

Does anyone know how to build a Synchroscope?

In AC electrical power systems, a synchroscope is a device that indicates the degree to which two systems (generators or power networks) are synchronized with each other.

This will be nice to link my 2 power stations up together or two generators

theChris 14th January 2007 05:51 PM

what are you trying to accomplish? do you know if your generators have any form of droop or cross-current compensation? these features are used to ensure current is shared between units.

Duo 14th January 2007 06:10 PM

Yeah, you'll need cross current compensation, something to deal with output voltage fluctuations, and something to maintain synchronous operation all the time.

You can use an oscilloscope to see what they look like in comparison to each other; but you need something a lot more sophisticated to maintain a phase relationship.

Either of the generators will have a somewhat differing frequency and voltage output and this will cause something to blow up or break down if you just connect them together.

I can't tell you exactly what you need to make them stay in sync with each other and balance the loading but I can tell you that this doesn't sound like a good idea given the style of generators you're likely to have.

moamps 14th January 2007 07:06 PM

While I was enlisted in the Army, I worked on a plant of four old Russian 150kVA AC generators. Their synchronization was very simple. There was one signal bulb, which was connected between 2 phases of two generators. The bulb was flashing or lit up when the generators were out of phase. My job was to change the frequency and output voltage of one generator until the flashing/light of the bulb started to slow down or eventually stopped. When that happened (i.e. when the generators were in sync), I would connect the generators in parallel.

When the first generator was loaded, the second generator would not start taking the load off the first one until its output voltage was increased a bit. Individual loads of each generator were regulated by fine-tuning their output voltages.


Duo 14th January 2007 09:19 PM

Must have had some very stable generators for the phase to stay in place during operation without constant adjustment.

moamps 14th January 2007 09:26 PM

Not really. The generators kept each other in sync. I had to make sure they had enough fuel, which proved to be a far more challenging task.;)


N-Channel 15th January 2007 03:34 AM


I concur with moamps. A good friend of mine, Ham radio operator and Senior Field Technician for Detroit Edison once told me how they synch multiple generators. Atthe power station, they get their peakers (BIG trailer-mounted 10MW Generators added to the grid for the summer) synch'ed to within 5-10 degrees of the main generators at the plant, then throw the switch. The result: the units (physically) snap into synch, and stay that way until one or more units run out of fuel, which has never happened.

The lesson here, complex synchronization schemes are not necessary due to the nature of how the different machines interact with each other.

Hope this helps.

Kind regards,


Duo 15th January 2007 04:43 AM

The synchronisation you speak of would then be caused by current between the generators from phase differences forcing the generators physically into synch by decelerating or accelerating either/both generators.

Duo 15th January 2007 04:47 AM

PS: I notice an N8XO in your signature in morse code. Is that your callsign? (I'm ...- .- --... -- --- -.)

AndrewT 17th January 2007 12:50 PM

running all the generators in parallel is not a problem, they naturally stay in sync.

Bringing an extra one on line will be the problem.

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