I need Generator Help

[Dsanduril]

Did you ever find a label on the Vetus side to confirm the generator head model?

The GHS4, which I think looks like the pictures you posted earlier has this schematic:



That shows the windings as two coils and terminals where they are jumpered together. Whether the schematic is just that, or whether it represents the real world is a whole other question. I'd take a careful look at the coils (although you've put it back together ) to see if it looks like it is wound that way. Try to follow the blue and the white (brown) wire back into the coil and see if you can tell where they are attached. Look for another attachment nearby that might be the bridge between two coils. If you find something like that then you could probably center-tap. If it's not wound as two coils then I'd give it up.

Not uncommon for these generators to have a small 12V charging circuit, although I don't see it anywhere on the schematic I'm looking at.

[Rocketman]

From everything I have looked at so far it does look like it is a GHS4, As for taking it all apart again, that is not a problem, I don't think it would take me an hour to do that. But that is going to have to wait as I got to get back to other responcablitys.
Thanks again for the advice, I am sure I will have more questions later as I have turned this project into a mission.

[Dsanduril]

Well, if you succumb to the mission...

1. Take a look at the coil. It is composed of stiff, varnished copper wire. A join between coils can be as simple as two pieces of this twisted together, or a short length of flexible wire soldered to two pieces of the coil. If it is coil wire joined together it may have a flexible cloth sleeve over it (or it was flexible before it got varnished). If you can find that you can attach a lead there to get a neutral for 120/240 operation. If you cut it open and attach two leads that you bring out then you can choose your wiring for either straight 120 operation or 120/240 operation.

If you get past step 1 then:

2. Put in a different capacitor. I'm guessing 25uF, I think that's pretty typical in 60Hz generators. You're looking for a "motor run" capacitor, AC rated, and something like 350V or higher. They only run $10-15, but you may need to experiment. Maybe someone else here can give us actual equations, the capacitor has to balance the inductance of the rotor coil and resonate at the desired frequency. Know how it works, but not the math. If you have a good motor shop in town you might be able to get them to give you some old ones for testing, that way you could try a range of capacitance values without too much cost. You can buy them at lots of industrial houses, here's one:

Allied Electric 25uF Motor Run Capacitors

3. Goose the governor to get you up to 3600 RPM. The 18W is listed for that in the US brochure, so it should only require a tweak of the governor. That's getting into the engine side, not my ballpark, but sure someone here could assist.

Sounds easy, right?

[Rocketman]

Originally Posted by Dsanduril

Well, if you succumb to the mission...

1. Take a look at the coil. It is composed of stiff, varnished copper wire. A join between coils can be as simple as two pieces of this twisted together, or a short length of flexible wire soldered to two pieces of the coil. If it is coil wire joined together it may have a flexible cloth sleeve over it (or it was flexible before it got varnished). If you can find that you can attach a lead there to get a neutral for 120/240 operation. If you cut it open and attach two leads that you bring out then you can choose your wiring for either straight 120 operation or 120/240 operation.

If you get past step 1 then:

2. Put in a different capacitor. I'm guessing 25uF, I think that's pretty typical in 60Hz generators. You're looking for a "motor run" capacitor, AC rated, and something like 350V or higher. They only run $10-15, but you may need to experiment. Maybe someone else here can give us actual equations, the capacitor has to balance the inductance of the rotor coil and resonate at the desired frequency. Know how it works, but not the math. If you have a good motor shop in town you might be able to get them to give you some old ones for testing, that way you could try a range of capacitance values without too much cost. You can buy them at lots of industrial houses, here's one:

Allied Electric 25uF Motor Run Capacitors

3. Goose the governor to get you up to 3600 RPM. The 18W is listed for that in the US brochure, so it should only require a tweak of the governor. That's getting into the engine side, not my ballpark, but sure someone here could assist.

Sounds easy, right?

Acutally this does sound reasonably easy. I don't think I will have a problem at all with the engine, to get it to 3600 RPMs, and the center tap doesn't sound too hard. I wish I would have looked at the windings a little closer while I had it out. The capasitor may be an issue, but I am sure I can make something work. You have been a very good coach, and very informitive. Thanks so much.

colemj seemed to know a little about capasitors, maybe he can lead me in the right direction as to which one I need to get.

[Stray-Cat]

Originally Posted by Rocketman

Hooking up the volt meter the gererator was putting out 210Volts with no load, I suspect the RPM's may be a litttle low hence the 210Volts instead of 230.

Unless you are using a "true RMS meter" your voltage measurements may be out a bit

If your meter has a "frequency scale" you could confirm that its running at 50 cycles

[colemj]

The capacitor is for voltage regulation. It resonates with the auxiliary winding and induces a magnetic field (through diodes) on the rotor winding, which results in output from the main stator winding. Since I think inductance is linear with respect to capacitance and frequency, I would think that a starting point for determining the correct capacitor for 60hz would be to simply multiply your current capacitor value by 60/50=1.2. Try a 40uF capacitor. Make sure it is an AC motor run capacitor with a high voltage value (greater than 250V and the higher the better).

On the other hand, I may have this backwards...

Mark

[Rocketman]

Originally Posted by colemj

The capacitor is for voltage regulation. It resonates with the auxiliary winding and induces a magnetic field (through diodes) on the rotor winding, which results in output from the main stator winding. Since I think inductance is linear with respect to capacitance and frequency, I would think that a starting point for determining the correct capacitor for 60hz would be to simply multiply your current capacitor value by 60/50=1.2. Try a 40uF capacitor. Make sure it is an AC motor run capacitor with a high voltage value (greater than 250V and the higher the better).

On the other hand, I may have this backwards...

Mark

Thanks Mark

[Dsanduril]

So I found two sets of equations for this question, the simple one and the hard one. The simple one says this:

C=1/(2*Pi*F*Xc) where F is Frequency and Xc is reactive capacitance in Ohms. We don't know Xc for this generator, but, if we work backward from the existing 31.5uF capacitor at 50Hz I get:

Xc = 1/(2*Pi*F*C) => Xc = 1/(2*3.14*50*31.5e-6) = 101Ohms

Then going forward for 60Hz I get:

C = 1/(2*3.14*60*101) = 26.25uF

I don't have supreme confidence in either the equation or the value, because the other paper I found says this:

Reduced computational effort as only a 4th degree polynomial need be solved to yield the value of capacitance.

But, their graph, that only goes out to 50Hz, supports a drop in required capacitance with increased frequency:

[colemj]

There you go - I had it backwards (upside down?). So multiply your current capacitor value by 50/60=0.83 and you get that 26uF. You will only find run capacitors in certain values, so don't worry if you can only find 25uF ones (or something similarly close).

Mark

[Snootyfox]

Originally Posted by Rocketman

Here are some pic's.

Hi Rocketman, hopefully your still around the forum. I have acquired a Vetus GHS4 gen set and would be greatful if you could send me a photo of the wiring terminals on the regulator. I've attached a photo of mine but not sure if it is correctly wired.