# Kohler generator issue - no output



## addison (Nov 23, 2012)

Hello everybody, I am new to this forum and to working on generators. I recently bought a 3MM25 kohler generator with a K181 engine on it. I got the engine up and running and it seems to be running great, but I can't seem to get the generator working properly. I have attempted to google around and find a wiring diagram to help me out, but I haven't found much. This is my first generator that I've worked on and it does fascinate me. I have a few questions on some things that I would appreciate if you guys could enlighten me.

I took the controller off of the generator and I'm down to the bare minimum, the stator and rotor. The stator consists of 6 field coils which are connected in series as an electromagnet. There is 5 brushes and 4 rings. There is three slip rings that produce AC I believe. Then there is one larger ring that has two brushes on it. To my belief, this is DC.

To start off, I am just seeing if the rotor and the field coils all work. I hooked up a DC voltage to the stator, and put a screwdriver to it, it works. Then I run the engine and got a reading off of the commutator, and it is producing a small voltage(I only had a 9V battery to it). The voltage is only about 1.5V which I am not sure if that is good or not. Since the generator runs off of residual magnetism, I next put the two ends of the electromagnet and hooked it up to the commutator. This is where I get the issue, nothing happens. My theory is that the voltage should keep increasing, and therefore the electromagnet should continue to get stronger and it is a cycle until the magnetic force will stop the rotor from moving. I noticed this happened when I hooked 90V up to the stator and then tried running on idle. Once I adjusted the throttle, it started turning. 

I do not think this is because of the wrong polarity because I have switched everything and did every possible combination on the commutator. Also, I don't think it's brushes because I also attempted to put the electromagnet wires directly on the commutator. I also messed around with the condensers to see if that was an issue but I didn't see any results. Does anybody have any theory on why this happens?

Small questions I have from playing around with this problem:
Isn't three phase created when three field coils are 120 degrees away from each other?
If so, what is the polarity of the field coils? (Do they all repel/attract each other)
What does six of the field coils mean? Is it still three phase?
Since it's an even number, is there one North and South at each opposite end?
Would the larger slip ring with two brushes be a commutator?
This is an odd model because it's frequency is 180hz. I plan to change it to 60hz or maybe even have the option to change it to 50hz. It also outputs 240V and I would
like the option between 120 and 240. To change the frequency I would need to change the RPM of the stator correct? Or would it be better to change the voltage to the
field coils?


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