Author Topic: Changfa 195 lazy governor  (Read 8364 times)

mjn

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Changfa 195 lazy governor
« on: March 08, 2006, 07:13:48 PM »
Hi Group.

I am totally thrilled to find this forum. (I followed a link on rocketboy's site).

After drooling over a listeroid for 8 months, I purchased a Changfa 195 from Joel on ebay in hopes that it would help ease the symptoms of listeroiditis.   Unfortunately the symptoms still remain.  In the meantime, I a least have a diesel project to work on.

My engine is direct connected via a Lovejoy l-150 coupling to an ST 7.5 gen head.  So I'm running the engine at 1800 rpm instead of the rated 2200 rpm.

At no load, I set the speed to produce 61hz (as read on a kill-a-watt meter).  As I start applying load, I can hear the engine picking up and working harder, but at 3000 watts load, I'm under 60 hz.  At 6000 watts, I'm running at 57 hz.  As I approach 7000 watts I'm down to around 55 hz. At 7000 watts the engine is starting to smoke, but nothing really heavy.

The engine has plenty of power to carry the load because I can manually re-adjust the speed back to 60 or 61 hz.  The problem is that when the load drops off, the engine overspeeds and I end up making 250 volts at 65 hz.

From what I have read on George's site, it seems that the Changfa engines have better governors than the listeroids, but I would hope for much better speed regulation than what I'm seeing. 

Is this normal?  if not, what are my options for improving my speed regulation.  I'm considering a microcontroller based system to automate the generator, and it would not be too difficult to add a stepper moter to "assist" the governor, but it really seems silly.

-------------------
mjn   
Changfa 195 WVO conversion in the works
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

DirtbikePilot

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Re: Changfa 195 lazy governor
« Reply #1 on: March 09, 2006, 04:03:57 AM »
I have some experience with that problem. Get a longer spring, one that doesn't have as much change in tension per length stretched. If you get a spring that is too long, the governor will be unstable and occilate up and down. Too short and you will have the problem you have now. You will have to figure out how to mount the longer spring because obviously it won't work with the original mounting points.
Currently no listeroids, sad........ very sad.....
Just some other antique engines ranging from 40 pounds to 33,000 pounds each.

Jim Mc

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Re: Changfa 195 lazy governor
« Reply #2 on: March 17, 2006, 03:54:04 AM »
The 195 is rated at 13.4 HP at 2200 rpm.  Since you're running it at 1800 rpm, the available HP drops by approximately the ratio of 1800/2200, which works out to about 11 HP.  Assuming 75% efficiency for the ST head, at 6 kW it'll need about 10.7 HP.  In other words, 6 kW represents about full rated load for the engine.  Dropping from 61 to 57 Hz is about a touch over 6%, which seems pretty reasonable.  I can't think of any loads in the typical house that would have trouble with that.

Voltage droop may be another story, though....








mjn

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Re: Changfa 195 lazy governor
« Reply #3 on: March 19, 2006, 06:47:21 AM »
Dirtbike:  Thanks for your input.  I'm searching for the appropriate spring.  So far, all of the springs in my junk pile are too stiff.  There is about .75 inches of adjustment on the spring mounting point.  Hopefully that is enough room once I find the right spring.

Jim Mc:  I did some tests to see how much power I can actually produce with the 195.  In addition to running at 1800 rpm, I'm also at 3500 feet elevation so I  have that against me as well.   In my earlier post, the watt readings were quick guestimates and turned out to be a bit high.

By adding load 1000 watts at a time and adjusting the frequency manually back up to 60 hz, I was able to find the maximum power point.   Your estimated max power of 6kw is very close to what I can get out of the engine without creating lots of smoke and still keep at 60 hz.   I start seeing smoke around 5700 watts.  Above 6000 watts, I can no longer adjust the speed to keep the frequency at 60 hz.  At 6500 watts the engine is wide open making clouds of black smoke.  The frequency is down to 58 hz and the voltage is down to 225 pulling 29 amps. 

You are also correct in observing that the loads in the house should have no problem with the 57 hz frequency.  At that load level, the voltage is 222 volts which is lower than I would like to see.

All in all, I'm quite pleased with how well the 195 handles the load.  Especially considering my elevation which by all rights should prevent me from reaching 6000 watts.  Hopefully I can get the governor working up to my expectations
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

mjn

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Re: Changfa 195 lazy governor
« Reply #4 on: March 27, 2006, 09:24:16 PM »
..snip. Get a longer spring, one that doesn't have as much change in tension per length stretched. ..snip...

Over the weekend I rigged up a mount where I could try different length springs.  The stock spring is about 1.5 inches long.  Using a standard load, with no load freq set at 60 hz I tried a 2 inch spring with no noticable affect at 57hz. A 4 inch spring,  is a bit better at 57.5.  A 6 inch spring is better still at 58hz.  An 8 inch spring gives me 58.5 to 59 hz.  I consider this an acceptable level governing, but it is still not perfect because the speed hunts up and down .25 hz.  I don't know if this is because it is too long, or the whole spring is vibrating in harmony with the engine.

All of the springs I'm using are from an old desk lamp.  I'll keep poking around looking for other springs to try to find a better match.

You can see my work in progress on my Changfa Generator Page:http://martin.nile.googlepages.com/.
--
mjn
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field

solarguy

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Re: Changfa 195 lazy governor
« Reply #5 on: March 29, 2006, 04:07:10 PM »
My best spring combination on my 6-1 Lister turned out to be two springs.  I use the original shorter factory spring, plus a second longer "softer" spring that exerts no additional tension until you add load.

I figure the different spring lengths and tensions work together to beat any funny vibration/harmonic issues.

Good luck and have fun!

troy

DirtbikePilot

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Re: Changfa 195 lazy governor
« Reply #6 on: March 30, 2006, 05:22:39 AM »
It really has less to do with the length of the spring than how much the tension changes per amount stretched. Usually a longer spring has less change in tension per unit of length stretched. If they are all too stiff, then none will be much better. Try to find a spring that has to be stretched quite a bit to maintain the speed you want.
Currently no listeroids, sad........ very sad.....
Just some other antique engines ranging from 40 pounds to 33,000 pounds each.

mjn

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Re: Changfa 195 lazy governor
« Reply #7 on: April 05, 2006, 07:25:01 PM »
Quote
  Try to find a spring that has to be stretched quite a bit to maintain the speed you want.

Thanks Dirtbike,  That helped.  I found a softer spring that behaves just like the 8 inch mess that was my best attempt to date.

Here is my hacked together test mount with the 2.5inch soft spring.


Now I just need to rig a better mount. 
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field