Micro CoGen.

Quote from: rl71459 on December 23, 2012, 11:35:35 AM
That is one nice old genset! Your refurbishing looks great so far.

Rob

Thanks Rob! It's a part time effort, so it's a bit slow going.  On lunch breaks at work I have been going into the shop and cleaning, blasting, painting things, as I don't have a blast cabinet at home. The generator housing does not fit into the blast cabinet so I have stopped that until I decide how I want to get that cleaned up. But I have the engine running now after cleaning the magneto breaker points. Video here:

http://www.youtube.com/watch?v=qYhKVk2wO0c

Notice the little pieces flying out all over.. those are little pieces of an evergreen shrub that this generator must have been sitting close to or something, because there are little pieces of it in the cooling fins. When I shut it down it smelled a bit like pine needles. How very Christmas-y!

Runs really well and has good compression. I'm just not really happy about the bits of rust I found inside the crankcase, but from sitting that's to be expected. The connecting rods have a little rust/pitting on them, and the tapered crankshaft bearing at the rear of the engine has etching from sitting in one position for so long. I may just replace the bearing cup (fairly easy) and hope it lasts for a while, because I'm not taking it apart right now.

I've cleaned and sealed the armature and the field poles with electrical varnish.. It's almost ready to go back together and be wired up for testing.

Quote from: Thob on December 23, 2012, 10:58:32 AM
Veronika,

I agree with your electrical engineer friend.  Switch SW1A, contacts 2&3, is part of the start switch.  When engage the start switch, this provides 24VDC from the battery, thru the diode, fuse, resistor, to the wire labelled "to F1".  This provides an initial flash to the field.  Once you let off the start switch, no more flash.  You could easily leave this out and use a manual flash as needed; or even connect a separate momentary contact switch in place of SW1A.  Engine running, no AC power?  Try a short flash.

Oh this is a good idea, and easy to do...  I think I'll just put a push button momentary switch in there for now. I may not even need to flash the field anyway depending on how much residual magnetism there is after each run.

As soon as I get it set up I'll run some tests with a 240v compressor, space heaters,  and a 240v buzz box welder, and see how much the voltage boosts or drops. Then I'll hook up the el cheapo chinese AVR and rerun the tests and see the difference. I don't have a high quality AVR, so unless someone wants to send one to me I can't prove for sure that this is an indication of how an AVR would work in general, only how mine works.

V

Some more pics... plus the reactor coil after I cleaned and sealed it.

Thanks for the welcome Bob! I have in fact learned a lot by just reading through this forum. Hopefully I'll contribute some useful information as time progresses. Once it's back together, I will in fact post some numbers that I come up with during testing. I've got a 240v air compressor, and of course air conditioners, and some various space heaters and things to really put a load on it. This unit is very beefy, I'm sure it's been underrated.

It is actually a three phase, 15kw 120/208Y gen head that I'm going to connect zig-zag for split phase power. This generator was available in three versions... The one I have, plus the split phase 120/240 version (that I posted the schematic here for), then a three phase, three wire delta version. The only difference between them is the armature.. this is a statically excited alternator with the field poles on the stator, power is taken from the armature via slip rings.. The transformers are the same between the models, just hooked up a bit differently in the schematic.

I did in fact clean up the transformers. Since they were pretty well sealed on the top, nothing got into the windings. So I wound up just cleaning the rust off of it, degreasing the outside with contact cleaner, and spraying them with clear electrical lacquer to seal them. I can't seem to find the picture I took after i cleaned them, but they look a lot better.

Although those transformers looked bad, the overall condition of the generator is quite good considering. The brushes look like new. There is very little rust anywhere else, just some surface rust. I'll attach a few before and afters where I'm at now with it if anyone is interested. Pictures are always nice in my opinion. 

I see what you mean about the air gap on the transformer now... the gap between the top and the body of the transformer. There is indeed a spacer there between those two parts. Makes it a lot easier to rewind, as you mentioned.

I sent this schematic to a friend of mine (an electrical engineer) and just finally got a response. Supposedly the line coming from the controller circuit on the right provides a small amount of voltage to the field when the run/start switch is engaged to help the field build up, then once the field builds up the transformers take over the excitement. It's almost kind of like flashing the field I guess, just gives it a little boost to help it get going.

The diodes on the right prevent power from the field circuit from backfeeding into the controller circuit. The variable resistor is there to fine tune the voltage so that it doesn't affect the field once the field voltage builds itself up, and it's not needed anymore.. I'm guessing if this isn't set correctly, then when the generator is unloaded, it could feed extra unneeded power into the field circuit, and affect the voltage.

Supposedly this works similarly to an alternator idiot light on the dashboard of an old car, but hooked up with a lightbulb in the circuit. Turn the key on and it's feeding the field, light is on. Start the car and the field builds itself up in the alternator, this circuit stops feeding power into the field anymore, and the light goes out. If the field gets weak, this circuit feeds more power into it and the light starts to glow... indicating a possible charging problem.

I did save most of the original parts, some were missing when I got it. I do want to keep the transformer system for excitation, but I want to replace the controller and battery charging circuit with something more modern, or at least rewire it and replace the old Potter-Brumfield relays with something more common and easier to find... Something from the automotive world probably.

If worse comes to worse, I have a cheapy chinese AVR sitting here that I can use to get it going temporarily. Maybe I'll do some comparison testing between the two, Then we can see exactly how much better the transformer is. Well, at least how much better is it than a cheap chinese AVR. 

Some pictures attached for your entertainment.

Here's a pic of The big honking transformer and reactor from the schematic... No way of adjusting it from what I can see...

This is before I cleaned them up... they look much better now! And I tested them for shorts... all seems to be good..

Thanks for the reply...

This is the only schematic that is provided on Winco/Winpower's website for this model... I'll try and contact them and see if they have any more information on it. I have found a few service bulletins that have been helpful, such as the thyrector being replaced with varistors.

The part I am talking about is, on the right, where it says "To F1". This line comes out of the circuit on the right, through some kind of diode bridge/rectifier, a fuse, and that variable resistor shown right there, then I guess is supposed to go to F1 on the left.  I circled it, I'll attach it.

There are no air gaps on this transformer. It's just a big honking transformer with the line 1 and line 2 going through it, and then the secondaries coming out. There are four secondary wires coming out  but two of them are joined together, like they are two pairs connected in series.

Hi everyone, first time posting. I have been reading this site for a while but never had a reason to post until now... This isn't an ST generator question, but there is another thread for the transformer controlled excitation type of generators, so I thought maybe this was the proper place to put it.

I have a Winpower GR15W4 generator that I am restoring to working order, and maybe updating it a bit while I'm at it. It has this transformer controlled excitation system that is mentioned in another thread, and I'm looking for perhaps a bit of help from some of you guys who know more about this than I do. 

I picked it up for a couple hundred dollars from an acquaintance. It's in good shape for being in a barn for decades. The Wisconsin V4 motor runs like a top, but the generator controller box had rodents move into it and was full of hay, and from years of people splicing into the wiring, it was a mess.

Anyway, I am restoring it. I ripped out the old system of relays with the rat's nest of wiring (and the mouse nests of hay) and am blasting and repainting parts.

I was going to replace the transformers with an AVR, but after reading about how good this type of excitation system is at starting motors I'm thinking about keeping it. I do want to replace the old-school relays and switches with a more modern controller.

The problem is this: I can figure out how to hook up most of the excitation system as it was largely separate from the controller circuit. But there is one line that runs from the controller circuit to the excitation circuit.. and it has a variable resistor on it. I'm assuming that this is to fine tune the power to the field somehow... but I'm not sure. I'm eliminating the controller circuit and replacing it, so I need to find out exactly what this does, so I can figure out some other way to make this work.. I'll attach the schematic so you can see what I mean.

In the schematic I posted, the excitation circuit with the transformers is on the left, controller circuit on the right. I ripped out all the controller stuff that you see on the right side. The battery charging transformer has been eliminated too. But on the right side you can see the line that says "To F1", which has the fuse and variable resistor, then runs to F1 on the left.

Am I correct in thinking that this is to adjust the field a bit?

I'm not an electronics expert as you can tell. 

Any help you guys would be able to offer me would be greatly appreciated!

Thanks!

Veronika