Generator flywheel ?

[iamowen]

Hi new to this, I was thinking, with all this talk about flickering power from generators, wouldn,t a large flywheel on the generator head help to eaven this out by absorbing some if not all of the drag when you pull more power, leaving the cs left with only small fluctuations to compensate for

[Jim Mc]

Sure, It'd do pretty much what you describe.  Like a lot of  things, though, there's a tradeoff.  In this case, adding mass to the generator flywleel will put increased stress  on the belt driving it.  The engine 'wants' to speed up and slow down during its 4 stroke cycle.  The flywheel on the generatorwon't.  So, the belt drive system has to 'pull harder' to try to speed up or slow down the generator.

Some of us have had problems with the belt chirping a bit, already.   Adding this flywheel will make that worse.

[iamowen]

   There must be a happy medium somewhere, perhaps the belt chirps because there is no flywheel on the generator? and wont if you use one, Huh maybe someone knows more about it

[rbodell]

Some of us have had problems with the belt chirping a bit, already.   Adding this flywheel will make that worse.

My belt was chirping once but after aligning the shaft square with the flywheel surface it stopped. It wasn't much either, I just dicovered it by chance when i adjusted one side back more than the other and it stopped.

nother time I made it chirp because I didn't loosen the belt enough to take it off and stretched it on one side. It took a long time to stop that time.

[dieseldave]

 

   Dont forget that the type of 'finish' (paint) will play a role in all of this. What about a non-slip surface?  A good quality enamel with very fine silica sand mixed in.

   Apply it with a 4 inch trim roller,while someone else hand cranks the engine,to get a smooth finish! Do the same with the Generator Pulley!

[rcavictim]

 

   Dont forget that the type of 'finish' (paint) will play a role in all of this. What about a non-slip surface?  A good quality enamel with very fine silica sand mixed in.

   Apply it with a 4 inch trim roller,while someone else hand cranks the engine,to get a smooth finish! Do the same with the Generator Pulley!

Get a hold of some Indian factory crankcase paint.  Apparently that has a lot of sand in it.   

[iamowen]

  ;)Coldn,t have put it better myself

[ronmar]

Flicker is a factor of any single cylinder generator.  It is just more noticeable on listeroid generator plants because of the low RPM engine and the 3:1 gearing causing a greater fluctuation of the generator RPM.  Because of this gearing, the RPM fluxuations have more time to effect more AC cycles,   Here is a graph of a listeroid power plant over a complete 4 cycles of operation.  The lower AC waveform represents 60HZ AC as relates to a 650 RPM engine.  As you can see, 2 engine revolutions effect a lot of AC cycles.



The flicker is more prevalent at greater engine loads.  Adding mass to the rotating machinery at any point will reduce the effects, but you will never completely eliminate them thru greater mass.  As mentioned adding to the generator mass puts added strain on the belt drive.  Adding the mass to the engine flywheels would have the same result in reduced flicker, but would add greater strain to the crank, pushrod and bearings.  That is how the SOM's did it with really massive engine flywheels, and from what I have heard they work pretty well. 

If you want to reduce most of the effects of flicker, add an AVR.  It will sense the decreasing generator output and add or remove field current accordingly to compensate and maintain a more stable output voltage.  You will still have frequency fluctuations, but they are less noticeable in incandescent lights. 

Probably simpler than an AVR would be to copy what someone else already thought of.  Some older Onan gensets had what were called "Flicker points".  These were electrical contacts driven off the engine camshaft and switched resistance in and out of the field circuit to increase and decrease the generator output throughout the 4 engine cycles.  On the above diagram, some resistance in the field would be switched out/bypassed at the end of the exhaust stroke, adding to the field and generator output as the RPM decreases thru the intake and compression strokes.  This resistance would again be added sometime during the start of the power stroke to lower the voltage output as the engine RPM peakes.  This of course would require an additional cam or some type of switch mechanism to accomplish.  With some carefull adjustment, it would probably greatly reduce flicker...

Ron 

[iamowen]

   Hi ron i understand where your coming fron but as i,m new to generators canyou draw me a diagramme of how to fit an avr ?   please

[ronmar]

Well that would depend upon the AVR, and what type generator you are running.  I understand you have an original 6/1?  What type generator do you have?

In general, the AVR connects to the generator AC output and feeds back some of that energy to the field winding to maintain the generator output voltage.  They can be pretty expensive though.

If you have a ST type head and are electrically inclined, you might build your own from the plans up in the "lister based generators" section.  There was a gentelman from Canada that was selling generic AVR's at a reasonable price up in the "Lister Market place" section.  I tested one of these and it works pretty well on my ST-5 with a noticeable decrease in flicker.

Ron

[Petersbpus]

I ended up having to put an AVR on my ST-12  to cure a low voltage problem and received the extra benifit of reduced flicker.
Besides the voltage adjustment pot, they or at least all the AVR's I have seen have a ramp or stability adjustment pot also.
Expect to spend $125 to $180. depending on model.
 The first step is to measure the resistance of the  exitation field windings (at rest).
You can also measure the exitation voltage across the brushes while running to be sure the AVR's output range is a match.
Doing this with my cheeeep meter the reading fluxuated ,wildly but generally were 50 to 60 vdc.
The resultant voltage stability  of the AVR made all my equipment that contained a computer chip happy.
Bob