synchronizing

[BrianK]

I would like to get someone to tell me how to setup synchronizing lights to work with two gas gennies. Any help would do.

[Electric Ed]

The only sketch I have is of a basic three phase setup. For single phase just use two lights.

Actually one light would do, as they are simply serving to indicate whether voltage exists or not, between the two machines.

EE

[Ungrounded Lightning Rod]

Note that you need a bulb capable of handling twice the votage of the generator.  When they're 180 degrees out of phase the voltage is doubled, wattage quadrupled (which will pop a bulb that isn't up to it).

Bulb(s) will brighten and dim cyclicly, as the gennies go in and out of phase.  It's out (or dimmist) when they match, and that's when you close the switch to hook them together.

If you have control of the speed of one of the gennies (preferably the "offline" one) you adjust it so the cycling slows down as much as practical, to minimize the currents when hooking the gennies together tries to force them to run at the same speed.  (The current through the bulb(s) actually helps this process slightly.)

[troy]

Of course, I have no idea why you are doing this or what kind of machines you are hooking together.  But if you are working with a typical consumer grade generator, its low mass engine and flywheel and it's so so quality govenor/carburator may preclude the possibility of a stable synchronization.

Loss of syncronization may result in damage to both machines...

Good luck, have fun, play safe.

troy

[Ungrounded Lightning Rod]

Mark Krueger actually did this sort of stuff for a power company and describes the process (better than I did B-) ) in another posting here.

Note that:

 - He used the one-hand-clock device rather than the blinky lights.  (That has a single hand, like a second hand, that spins around showing the relative phases, with a single mark at "noon" when the genny and the grid are in phase.

 - He was synchronizing a big genny to the grid, not tow gennies to each other.  The deliberately ran the genny 5% fast (about 3 blinks per second for you) so it would source power, rather than eat power, when it went online.  The grid is a thousand-pound gorilla compared to the genny so it won't start slewing frequency because one more of the thousands of generators came online a bit off speed.  (Your situation looks like connecting two gennies of roughly the same size, so you want 'em running closer to the same speed because they'll both try to change when you close the switch.)

[Flux]

Troy has a  point.

Small generators are not good at staying synchronised. If you have single phase, my advice is don't do it.

If they are 3 phase and designed with droop to share load and have good governors they may be ok.

If they are widely different machines it may not be so good.

If you try it, make sure you have circuit breakers that will trip at about full load for each generator.

If they pull out you may damage the exciter or voltage regulator if they have them.

Flux

[BrianK]

Thank you all for the comments. This is just an idea that I was playing with. I might not make it real. Don't want to ruin my gennies.

     

[Bill Kichman]

Another thought when parallelling gensets is sourcing/sinking.  Say you are using induction generators (induction motors spun faster to make power instead of sinking it).  Now let's say one of the gensets runs out of fuel.  The dead genset will now motor, drawing about as much current as it is capable of delivering, maybe even more.  The best way to fix this issue, since measuring AC current direction is no simple task, is by using a Reverse Power Relay.  The device compares the phase angle of both the current and voltage, and trips a relay to signal sinking istead of sourcing current.  The relay could control coil power for a big power contactor, interrupting the problem automatically.  I discuss this because I had the need to do this same thing.  Was able to locate these relays pretty cheap on Ebay BTW.

I am not sure how other more typical single phase generators would cope with this issue, but I imagine they wouldn't motor, but might be damaged due to the high currents when they slow down so it would be a good idea to apply one there also.

Hope this info helps...

[(unknown)]

I work with generator controls for a living. You have multiple problems when running two generators on a parallel bus:

The voltage sourcing/loading, which we call reverse power, mentioned by the previous poster.

KW load sharing.  Essentially the two generators need to provide the same power to the load.  This is typically accomplished with speed (fuel) controls.

KVAR load sharing.  This is the current equivalent of the previous.  This is typically accomplished with exciter (voltage) controls.

Over-current protection.  Typically provided with circuit breakers.

Over-speed protection.  This happens when one generator set drops its load.  Flyball governors (centrifugal fuel reduction) or other electronics measuring frequency can provide this function.

Undervoltage protection.  This can cause brownouts and damage your load(s).  This won't really hurt the generators themselves, but what good is a generator when all of your electrical systems are fried?

Overvoltage protection.  Typically, this is caused by faulty exciter controls. About the only thing to do is shutdown the generator and fix the problem. Sometimes, overvoltages are caused by loads dropping suddenly off line.

There are probably a few others that I haven't mentioned, but this list gives you the idea that this isn't child's play.

If you're doing this with permanent magnet, wind-driven generators, then I'd suggest you rectify the output and feed that voltage into batteries, like nearly everyone else on this board is doing.

I'd be happy to offer advice to anyone trying to do this, but it is more difficult than just getting them in sync before closing the breaker.

[Bill Kichman]

Yes, the previous poster is absolutely correct, I was simply answering the question.  In my setup I own a set of Eaton IQ Data Plus power quality monitors which I will use to obtain the KW, amp, KVA and voltage info for control feedback of each generator, and when utility connected, that of the utility power leaving/entering my building, but also they have inherent over/under voltage and other control features built in, and directly control a relay to trip out the load if need be.  The control system for my cogen operation will be Labview software running on a PC, with a pair of DAQ cards for analog and digital IO's.  

There are simpler ways to accomplish this, albeit with lesser flexibility, there are ready made multi purpose protective relays or generator control packages you can obtain to provide all these features.  

But yes, it isn't a simple as just wiring 2 120v lamps in series across the 2 lines, but that is one way to reduce the large currents when synching 2 similarly sized gensets or a genset with the utility.