Brian's Morning Newsletter

Monday March 8th 2010

Good Morning

We've been working on an older Kohler Diesel generator: 17.5 ROY (17.5 KW) trying to isolate a fault which keeps the generator from making it through its 60 second post. Three conditions can set off one of two  reset breakers: Over cranking, (starter running too long) Low Oil Pressure, and Coolant Over-temperature, which are tied together, one NC (normally closed) one NO( normally open)  Anyway after trouble shooting while forcing the IP (injector pump) on, to keep the engine running we ran controller board tests, rectifier module, and rotor brush tests, the controller board went from bad to worse. The good thing is we have a clear understanding of how these carbon brush generators work. For one thing this genset has a standard nine wire configuration on the generator head output, meaning wiring several different Delta and Star configurations are possible, this one configured as single phase 120-240 same as a US home.

There is a fairly exciting method for manually exciting the generator. My point is we discovered a fascinating correlation between the rotor voltage and the stator output. Apparently this is how this style of generator maintains constant voltage. By feeding-back a reference voltage from, in this case L1-L2 (line 1 = 120 volts AC)the AVR (automatic voltage regulator) signals battery charging alternator on the diesel engine to put out more or less voltage which in turn alters the voltage to the brushes on the rotor. It is really quite elegant. Unfortunately, none of these functions were working for us. Like I said we manually excited (per the service manual) the rotor and got an output from L1-L2 albeit erratic and unregulated.

After determining that the generator was pretty standard, I'm an old hippie VW mechanic, my son-in-law is a journeyman electrician, plus we had the owner here in our recently built renewable energy (partially axial flux wind turbine powered) shop in northern New Mexico, we are confident the controller board is malfunctioning in more than one arena. If you know me  you know what I'm thinking, "this would be a fantastic genset for us here on the ranch." Without checking with my wife and before we finished trouble shooting I offered $2,500 for the Genset. The owner said yes, we proceeded with the trouble shooting gambling that it was going to work, but not really since I was only able to make payments.

Long story, I know, but this is an evolution in thinking, combined with a touch of a naive outlook, I forged forward. I had heard some new generators could be grid-tied. Now we see how this is possible, by employing a feedback loop from the house electric instead of the output of the generator the phase and voltage can be matched. Cool, cool, I want to play.
So I went InterWeb-surfing, looking for first, a replacement controller from Kohler or any after market manufacturer, which proved that even if the proper controller was available, it was going to be ridiculously priced, to the tune of $1000 plus, so I continued surfing and came across this  http://www.allproducts.com/manufacture2/kutai/Product-20076685448.html
 
    
"EA45A220F (Full Wave) and EA45A220H (Half Wave) 45 Amp universal self excited genset voltage regulator compatible replacement for carbon brush type generators. There are also optional low frequency protection available."

This device looks perfect, except that no matter how hard I searched I could not find a company that sells them, thus no idea if this is a $100 or a $1000. I modified the search parameters and came to this: http://www.ab.com/PEMS/cgcm.html "Power & Energy Management Hardware  Combination Generator Control Module (1407-CGCM)

The CGCM consists of a single module that provides multiple functions needed to implement a generator control system. It supplies controlled excitation current to the generator field winding in order to produce the desired generator output voltage.

The CGCM also measures the generator field current, the generator output voltage, and the generator output current. These measurements are used to implement a variety of protection functions to insure the generator operates within its design ratings. In addition, the CGCM measures the voltage on one or two reference busses. This additional information provides the data needed to synchronize the generator output to the selected reference bus to allow the generator to operate in parallel with another generator or the utility supply. All of the measured data is available as full featured metering data. Access to the CGCM data and functions is provided via a standard ControlNet communication port."

Again, no idea of a price, although this one looks very expensive, but it makes me think. The technology is here and available now. Not that we would spend $1500 on a refurbushed control board for the genset, but the idea that a modern control board retrofitted to the 17.5 KW genset could make the machine Utility grid-tie compatible creates a possible return on the investment. For instance running the engine on biodiesel, and or WVO, or WMO means we would cut the monthly electric bill by running the genset for a day now and then, for that, I would spend the money.

So my question is, have you seen after-market grid-tie genset controllers made fro carbon brush rotor standard nine wire generators and can you provide feedback and perhaps a link? Or am I thinking ahead of the current technology?

Shear mechanical madness did not occupy my entire weekend, indeed I painted as well. I finally splotched paint on one of the canvasses Nell's sister Susan sent me. Please forgive the sloppiness, this painting is still in the early stages of development.  Acrylic paint is forgiving, thank goodness. I have already  made major changes to my native American Ghost Dancer as I call this work.  As  Usual I feel there are as many features and techniques I dislike  about my painting as there are things I like.

Working on a large canvas is easier. I get to focus attention on the hands and feet as I wanted to, and please don't laugh, hands and feet are almost as difficult as faces, yeah pretty much everything I feared was realized. Still, I have hope. I sort of got one foot and one hand to come-out. I had to go and pick a subject that was blue on one side and flesh on the other. It is completely different figuring out how to shade and shadow in blue as opposed to flesh, which I admit I hadn't done yet either.

Oh, should I show you the model photo?

Good luck with this, right?

Well, there it is I suppose

Brian Rodgers

Letters

Re: BMN Mud bog averted
Regarding the mud bog road -

"This book addresses the construction and maintenance of unpaved rural roads including strategies, techniques and practices for dealing with problems frequently encountered by landowners, land managers and maintenance personnel. Running water is the primary force affecting road condition and generating the need for maintenance. Economical maintenance means dealing effectively with water, but not just surface runoff. Standing water, seeping water, rain, snow, ice, frost and even a lack of water can contribute to road maintenance needs."
Lee
—–    
Thanks Lee, that is a great little book
Brian       

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