...
Are you feeding a battery bank? or is the ST7 connected directly to a transfer switch ?

The generator is connected via a transfer switch.  After starting the generator, I throw the switch which disconnects the house from the utility and connects it to the generator.   Other than careful power management when running the dryer, we can use any electric appliance we like.   The only thing I need to fix is that I have no indication of when utility power returns.  (We have to look out the windows to see if the neighbors have lights on.)

Still waiting for my first power outage, at least one long enough to count. May I also mention mjn's website http://sites.google.com/site/martinnile/ it is a must read. I have learned a lot from you guys who have taken the time to document your experiences with these power plants. Thank you.

Thanks for the the kind words.  My whole purpose in building the website was to give back some of what I had learned from others on the net.

--
Martin

...snip...
Anyone know what type of throttle actuator solenoid to buy??

The Murphy RP2307B solenoid is designed to do exactly that.


Murcal has these available for $54 http://shopping.murcal.com/Catalog/Rack-Pullers/RP2307B-Push-Pull-Solenoid


The ECU-05 has an output that can be used to momentarily pull the rack closed to kill the engine.   On my Changfa 195, the best place to install this is directly on the governor fork where it meets the injector pump. 


In this picture, the fuel limiting adjuster has been removed. The green line points to the governor fork.  Pressing in on the fork will close the injector pump and kill the engine.  On my engine, the fuel limiting adjuster is useless, so eliminating it is not a problem.

Hi Kelly,

I've built an autostart controller for my Changfa 195.  You can read about it at http://martin.nile.googlepages.com/automaticgeneratorcontroller

Unless you are really handy with a wire-wrap tool and programming, you are probably better off with a $200 commercial product.

--
Martin

Chris,

I have built exactly what you are thinking about.  It works fine.  My biggest mistake was to add too many bells and whistles.  I would have been better off with just controlling the frequency, I ended up with a system that does everything except feed the cat.  You can read the whole story here: http://martin.nile.googlepages.com/automaticgeneratorcontroller.

As Jens pointed out, the trickiest part of building a PID controller is tuning the gain variables.  Mine is not perfect,  There is room for improvement.  I stopped tweaking when I got it to hold the frequency close enough to keep my APC ups happy.  I'm doing this with a Changfa 195 running at 1800rpm.  I haven't tried this on my listeroid. I assume it would take longer for the PID controller to catch any frequency excursions.

Here is a graph that shows how my controller behaves versus the stock spring.



When I add a 5000 watt load, the stock governor (purple line) drops to 1700 rpm (56.6hz) within half a second.  The PID governor starts picking up at .4 seconds and has recovered to 1800 rpm by 3 seconds.

This graph shows the behavior when the load is removed.


The spring governor behaves nicely and the rpm's return to 1800 within about a second.  The PID controller overshoots the mark by 60rpm (62 hz) but eventually settles to around 1800rpm within 1.5 seconds.

For your reading enjoyment, here is my fixed point implementation of the PID controller.
/*******************************************************
 * pidcontroller -- calculate the adjustment to the stepper position
 *
 * based on emprical tests: Pc=20, Kc=280
 *
 * Ziegler-Nichols tuning: pgain=0.65 * Kc  = 182
 *                               Ti=0.5 * Pc = 10
 *                              Td=0.12 * Pc = 2.4
 *                         dgain= pgain*Td = 182*2.4=436
 *                         igain= pgain/Ti = 18 *4 = 72
  * All gain values are multiplied by 256 so we can do
 * the arithmetic in integers.  The result is divided by 256
 *
 ******************************************************/
int pidcontroller(void) {
int error;
long pterm; // proportional term.  The pterm is long because on startup
// the pterm has a very large error when multiplied by the pgain
// will exceed the size of a normal int.
int iterm; // integral term
int dterm; // derivative term

int temp;


#ifdef PIDTUNE
pgain=(getadc10(3)-8)*2; // pc3 (uco empty) is temporarily used as a pgain control
if(pgain < 0) pgain=0;
igain=getadc(4)-8; // pc4 (diesel empty) is used as igain control
if(igain < 0) igain = 0;
dgain=(getadc10(1)-8)*4; // pc1 (watertemp) is dgain control
if(dgain < 0) dgain = 0;
#endif


error=TARGETRPM-rpm;

// calculate the proportional portion
pterm=((long)error*pgain);


// calculate the integral portion
// If we are at the stepper limit, and still want to go higher,
// do not add any more to the integral
if(!(PINB & LIMITHI) && pterm > 0) {
temp=sumerror;
}
else {
temp = sumerror + error;
}

if(temp > 5000){ // limit the integral windup
temp=5000;
}
else if(temp < -5000){
  temp=-5000;
}

sumerror = temp;
iterm = (igain * sumerror)/32; // note!! /32 gives us more fractional resolution for the igain variable

// Calculate the derivative portion
dterm = dgain *  (rpm - lastrpm);
lastrpm = rpm;

temp = (pterm + iterm + dterm) / 256;

// if the adjustment is less than 2 steps, don't bother
if(abs(temp) < 2) {
temp=0;
}

#ifdef PIDTUNE
putstr("\r\n");
print4(rpm);
putch(' ');
print3(pgain);
putch(' ');
print3(igain);
putch(' ');
print3(dgain);
putch(' ');
print5(temp);
#endif
return(temp);
}


I have been kicking around the idea of building a minimal frequency controller without all of the bells and whistles of my generator controller.  I'm thinking of using an 8 pin MCU and the guts of an old 5 1/4" floppy drive to apply a bias to the stock governor spring.  Total out of pocket expense should be less than 10 bucks for the CPU and hall effect sensor to pick up rpm.  Everything else is sitting in my junk box.

My Listeroid has had all of the water drained and buttoned up for the winter, so I won't be able to do any testing until sometime next year.

--
Martin

I know RAB was speaking somewhat tongue in cheek, but for the computer geeks, out there, it has been done.   My cpu (ATMega8) only cost $5.00 (including a/d converters and all).  That was the cheapest part of the whole thing.  You probably won't be able to get a stepper motor and leadscrew for anything less than $100.

To save you the grief of writing a PID controller.  Here you go free of charge...

error=TARGETRPM-rpm;

// calculate the proportional portion
pterm=((long)error*pgain);


// calculate the integral portion
// If we are at the stepper limit, and still want to go higher,
// do not add any more to the integral
if(!(PINB & LIMITHI) && pterm > 0) {
temp=sumerror;
}
else {
temp = sumerror + error;
}

if(temp > 5000){ // limit the integral windup
temp=5000;
}
else if(temp < -5000){
  temp=-5000;
}

sumerror = temp;
iterm = (igain * sumerror)/32; // note!! /32 gives us more fractional resolution for the igain variable

// Calculate the derivative portion
dterm = dgain *  (rpm - lastrpm);
lastrpm = rpm;

governorcorrection = (pterm + iterm + dterm) / 256;

That was the easy part, the hard part comes in tuning the gain variables.  These will be different for each and every system. Unless you want the fun of learning how to build a controller and program it, I don't suggest you do it.  You are better off experimenting with different springs until the oscillation goes away.

If you want to see how I built my controller, go to http://martin.nile.googlepages.com/automaticgeneratorcontroller.  Source code can be had at http://code.google.com/p/ngencontrol/

To show how my controller behaves, this graph shows the stock governor (purple line) versus PID governor (green line) when the engine load goes from zero to 5000 watts.


Note, it is normal for any P type governor (such as a spring) to exhibit "sag", or oscillation when load is applied.  You can minimize the sag by increasing gain (using a stronger spring). The system starts to exhibit oscillation when the gain gets too high.  In your case, you can minimize the oscillation with a weaker spring, but at the cost of having the RPM drop when load is applied.

My controller is great.  Unfortunately, I haven't figured out how to use a computer to make my Changfa any quieter.

I have developed a revolutionary new concept for emergency shutdown of a Lister type diesel engine.  The device can be constructed from materials at hand for mere cents.
 
Functional Parts
   1. Smelly Cheese sitting on engine
   2. Mouse Attracted to smelly cheese
   3. Cat attraced to mouse attracted to smelly cheese
   4. Dog sleeping
   5. Old boot attached via string to shutoff lever of engine

Setup
  1. A piece of smelly cheese is placed on the rocker arm cover of the engine. 
  2. This in turn attracts a mouse to the engine, but due to the fact that all properly maintained listeroid engines develop a protective covering of oil and grease, the mouse is unable to climb up and get the cheese. The mouse sets up housekeeping nearby.
  3. A cat is attracted by the presence of the mouse, and sets up camp to get the mouse.
  4. A dog is kept nearby because federal law requires that cats need a dog nearby to keep them honest.
  5. A boot is attached via string to the shutoff lever of the engine.

Operation

   1. In the event of engine overheat, the cheese will begin to melt and run down the engine.
   2. The mouse, seeing his chance will come out of his hole and start eating the cheese.
   3. The cat seeing the mouse, tries to catch it.  It is a well known fact that anything within shouting distance of a properly maintained Listeroid will become covered with oil.  The mouse, having lived near the engine has a protective covering of oil which prevents the cat from catching the mouse.
   4. The cat after having been robbed of a tasty meal of mouse, begins to caterwaul bemoaning his loss.
   5. The dog after having been rudely awakened from a nap begins to bark at the cat telling him to "shut up".
   6. The wife or neighbor upon hearing the ruckus picks up a boot and heaves it at the nearest offender.
   7. The string attached to the boot pulls the cutoff lever and shuts down the engine.

The operation in the case of overspeed is similar except that the vibrations of the engine will shake the cheese so that it falls off and the procedure begins at step 2 above.

April 1, 2008 Martin Nile

In addition to dealing with the exhaust noise, you will need to muffle the intake as well.  My Changfa makes nearly as much noise on the intake as the exhaust.   Once you get the intake and exhaust quieted down, then you can work on getting the mechanical clatter silenced.

Back when I was working on my computer controller for my 195, I picked 600 rpm to warm up the engine after starting.  When running at 600 rpm, the engine hammers quite a bit.  When I upped the speed to 1000 rpm, it seemed to smooth out and not put so much load on the lovejoy connector.

I haven't tried to see how much power I can get out of it at that speed, but 1000 RPM seems to be the lowest reasonable speed for this engine.   A larger flywheel like rcavictim has will probably make a huge difference.  (The flywheel on my 195 probably weighs 1/4  of what one of the flywheels on my 6/1 metro weighs.)