Author Topic: Voltage control and "Lister flicker"  (Read 10677 times)

EdDee

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Re: Voltage control and "Lister flicker"
« Reply #15 on: January 26, 2016, 08:48:39 PM »
Hey Bruce,

Lose the pulley, just run the inside of the v-belt on the outside of the flywheel.... I run up to a surge of 30A to 40A at 220v, ie 7 to 9kw  on 2 belts and a double sheave pulley on my gen head...  Belts haven't flipped over once yet, and I have only had to adjust tension once at around 1500 hrs or so....

You will of course have to change the pulley size on your compressor possibly, unless your big pulley is within 10% or so of your flywheel size, or your compressor can handle the extra revs....

Another big plus, for me anyway, is the easy removal of the belts... no de-tensioning, just creep them on or off the edge of the flywheel...no tools required.... Lazy works for me.....

Cheers
Ed
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BruceM

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Re: Voltage control and "Lister flicker"
« Reply #16 on: January 26, 2016, 10:09:25 PM »
I wholeheartedly agree with the use of vee belts running flat on the flywheel, Ed.  On the 8/1 clone propane conversion I just did for Jeff G., we use a single B belt driving the ST-3.  Works like a champ, no slipping or chirping on motor starts, no tracking issues, and quite cheap.  I tried it as there were a much wider range of pulley sizes available and it would make changing engine rpm and pulley cheap. Now I'm "sold" on it and I think the serpentine belts aren't worth the bother unless you find a bargain. The belt tension for vee belts is substantially less, which can only be good for bearings.

My two stage compressor has it's cooling fan cast into it's cast iron drive pulley, so it would be difficult to change the driven end diameter.  Could be done by adding a separate fan, of course, but in truth I've managed to get my flicker problems down via custom AVR to where I can live with it. 


George A

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Re: Voltage control and "Lister flicker"
« Reply #17 on: January 27, 2016, 01:24:26 PM »
Well, after thinking about it I'm not really sure an auxiliary flywheel on my generator shaft may be a good idea after all. That generator armature shaft was in horrible shape when I got it.....bearing seized and it kept running, scoring a big fat groove in the shaft. I welded it up, straightened it in my lathe and turned the excess weld off. It's accurate and strong enough, but the shaft is only 3/4" with a single row ball bearing (new) so it's not really beefy enough for a massive weight.

The only other solution that comes to mind is another flywheel on a jackshaft between the engine and generator. Although it would make the whole unit larger it would be an easy way to add rotating mass with no strain to the mechanical components. Playing around with different pulley ratios would be easier too.  I know where there's a junked hay press with a cast iron wheel of around 400 lbs. or so....

Nah, next year. The lights don't flicker all THAT bad!
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

M61hops

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Re: Voltage control and "Lister flicker"
« Reply #18 on: January 27, 2016, 01:37:46 PM »
I mounted 2 brake drums onto the crankshaft of my 6-1 Metro.  The drums were off the front of a 1 ton van so pretty heavy, stopped the flicker and could be used as pulleys at some point in the future.  Turned the hub to fit a taper lock bushing.  I first tried a 70 pound flywheel on the generator shaft but that wasn't enough and the belt chirped on the power stroke.  More mass on the crankshaft is the way to go.         Leland
I pray everyday giving thanks that I have one of the "fun" mental disorders!

George A

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Re: Voltage control and "Lister flicker"
« Reply #19 on: January 27, 2016, 03:12:40 PM »
I mounted 2 brake drums onto the crankshaft of my 6-1 Metro.  The drums were off the front of a 1 ton van so pretty heavy, stopped the flicker and could be used as pulleys at some point in the future.  Turned the hub to fit a taper lock bushing.  I first tried a 70 pound flywheel on the generator shaft but that wasn't enough and the belt chirped on the power stroke.  More mass on the crankshaft is the way to go.         Leland

THAT is an excellent idea! First of all the raw material is readily available and cheap. Second, the two drums are distributing the increased load between the bearings AND evidently add sufficient rotational force to help smooth out any fluctuations. On top of that, they can serve as additional flat belt pulleys if need be.

Where did you find the taper lock bushings? Were they the correct size or did you have to machine the centers?
« Last Edit: January 27, 2016, 04:14:08 PM by George A »
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

BruceM

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Re: Voltage control and "Lister flicker"
« Reply #20 on: January 27, 2016, 05:31:03 PM »
I thought the SOM flywheels were more than double the weight of the spoked, with most of this at the rim.   Those must be some seriously huge, heavy brake drums?  How about a photo, Leland?








Thob

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Re: Voltage control and "Lister flicker"
« Reply #21 on: January 28, 2016, 02:25:27 AM »
Somewhere I saw someone had taken a flywheel and crankshaft out of a gas engine car (junkyard parts).  They cut the end off the crankshaft where the flywheel mounts and bored a hole in the center to mount it on the CS crankshaft.  I think they may have used a taper lock bushing for the mounting, but I don't remember exactly.  Then put the automotive flywheel on this "adapter" that they built.  It also provides a ring gear that you can use for electric start if desired - you just need to mount the starter in the right spot (and make sure it rotates the right direction).

Be aware that a flywheel with teeth is slightly more dangerous than a smooth flywheel!
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
I'm not afraid to take anything apart.
I am sometimes afraid I'm not going to get it back together.

George A

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Re: Voltage control and "Lister flicker"
« Reply #22 on: January 28, 2016, 03:13:59 AM »
Great.........as if I don't have enough good ideas already  ::). It just so happens I have a couple of model A Ford flywheels in my pile, complete with ring gears. Anyone familiar with them knows how heavy they are................
« Last Edit: January 28, 2016, 03:16:09 AM by George A »
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

M61hops

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Re: Voltage control and "Lister flicker"
« Reply #23 on: January 28, 2016, 10:19:55 AM »
I wish SOM flywheels were easy to come by because they would look better and add a lot more mass than what I did.  But it's fun for me to re-purpose car parts for other uses.  I like to hit the U-Pull junk yard when they have sale days because I always need something anyway.  These brake drums were off the front of about a '70 Dodge van and not too common because most people popped the few extra bucks for disc brakes.  The front drums are a better shape than disc brake rotors due to the mass at the outer edge.  Also seemed better than a few engine flywheels I looked at for the same reason although a couple of flywheels might be enough mass if you chose well.  I'd guess the drums weigh about 25 pounds each and just one seemed to cure the flicker as I also have a real heavy pulley/flywheel on the generator shaft.  The area where the outer wheel bearing sat was a good size to turn a taper to fit an inexpensive taper lock bushing from Surplus Center.  The 2" ID bushings are pretty cheap from several online bearing supply houses also but I don't remember what they cost.  Brake drums or rotors for the rear axle would have a hole in the center that would be too big for a bushing.  At some point I will adapt an automotive flywheel to bolt to the lug studs so I can use an auto starter on the ring gear instead of the belt drive thing I have now.  I hurt my spine about the time I started playing with this CHP stuff even though I've been wanting to do it since I was about 10 years old.  I haven't been able to finish the install; or a lot of other projects.  I had fusion surgery and my spine has never been right since so I don't get much done in a day, or a year.  I've been wanting to make a video to show how much my engine hopped before I added weights to the flywheels, haven't got to that yet in almost 10 years, maybe I can post a photo a little quicker.  At the rate I get things done it could take a week or two until I can get to it.
I pray everyday giving thanks that I have one of the "fun" mental disorders!

George A

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Re: Voltage control and "Lister flicker"
« Reply #24 on: January 28, 2016, 11:02:57 AM »
M61hops, I can sympathize. I blew a disc in my lower back in 2008 and developed a spinal stenosis later in 2014. Needless to say, my working days were over and after two surgeries I went to a disability status until I reached 65 when Social Security took over. It's been quite a ride! I can still crank my Listeroid, but I'm awful careful these days.

Thank you for that very accurate description of the brake drum conversion and the information about the taper lock bushings. Ironically, my stepson is a certified mechanic here in town so keeping an eye out for certain parts is easy. I'll have a talk with him today at lunch and we'll see what "inventory" is available........:)
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

DirtbikePilot

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Re: Voltage control and "Lister flicker"
« Reply #25 on: January 29, 2016, 03:12:50 AM »
6/1 startomatic engines still have pretty bad flicker. My parents have one and the flicker seems just as bad as with the regular flywheels. I believe the only solution is to run the power through a battery bank and use an inverter. That's my plan with my Witte generator whenever I can get around to building it.
Currently no listeroids, sad........ very sad.....
Just some other antique engines ranging from 40 pounds to 33,000 pounds each.

buickanddeere

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Re: Voltage control and "Lister flicker"
« Reply #26 on: January 29, 2016, 05:27:47 AM »
  Sometimes adding a large DC capacitor across the brushes/voltage regulator output + & - leads will dampen variations in excitation. The circuit could be resonating with the firing pulses? It's not going to cost very much to experiment.   

George A

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Re: Voltage control and "Lister flicker"
« Reply #27 on: January 29, 2016, 11:17:56 AM »
That's an interesting comment about the SOM's...........after all, I've never SEEN one in operation and simply assumed that Lister solved the problem with the heavier flywheels. Maybe not so much and we're beating ourselves silly over a problem with no resolution?

As for a capacitor across the output, I have two in my Root and Kurtz but they're for radio suppression and have no effect on the pulses whatsoever. Now these capacitors go from each output leg to ground and are, of course, for AC use. My generator has a separate DC excitation commutator........maybe that's where you meant?
I've joined "the dark side"....if it has a spark plug, it's obsolete technology.

buickanddeere

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Re: Voltage control and "Lister flicker"
« Reply #28 on: January 29, 2016, 02:50:35 PM »
AC oil filled capacitors across the 120/240 output is a good idea to produce leading current to carry electric motor's lagging current without loading the alternator with reactive current. Won't make a lick of difference to flicker.
    What I was thinking of was a Large DC capacitor across the DC excitation circuit . If the excitation voltage is hunting, the cap will smooth out those swings in Excitation current and thus smooth swings in output AC voltage .

BruceM

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Re: Voltage control and "Lister flicker"
« Reply #29 on: January 29, 2016, 03:52:15 PM »
Subjective evaluation of flicker is highly variable, because things like incandescent bulb wattage and other factors play a role.  Some people can see flicker much more so than others.   

The SOM flywheels improve flicker only as much as my fast correcting AVR does... based on measurements with my low pass filter and an oscilliscope.  With my AVR I can now tolerate my 250 watt light/heat lamps for my shop which previously gave me partial seizures.   I can switch back and forth on my AVR to stock harmonic or AVR via 1 switch, and I made an RC low pass filter so I could measure the 5.5 Hz variation in AC peak voltage via oscilliscope.  It is dramatically improved. 

A responsive AVR could also now be applied to the SOM, something not very practical at the time of their design.  This would add that much more to voltage regulation, and I suspect even I, with epilepsy, could tolerate 60 watt bulbs with both SOM flywheels and my AVR with mains excitation. 

For most people, just changing to  LED lighting which regulates LED current via a small switching supply will totally eliminate flicker.  This is the simplest solution for people who can tolerate LED lighting.  I can't. 

As for B&D's suggestion of big electrolytic capacitors on the excitation side-  sounds good but absolutely not helpful.  If "smoothing" the excitation current was going to work, there would already be no problem as the rotor has huge inductance (a few henries) and is a highly effective filter in itself.  The underlying problem is that the engine speeds up during the power stroke, and slows down during compression.  This causes a big change in voltage out with a constant excitation current.  Because the frequency is varying, this requires large and rapid changes in the excitation current to try and maintain voltage output.  This is complicated by the lag in response by the rotor's inductance.  The correction is always too late, so only so much can be done without a much more complex electronic solution.  (A microcontroller would be required to anticipate the correction-  a fairly complex bit of real time control.)

The simple solution is to switch your lights to something self regulating.  If you must use incandescent bulbs, then a fast AVR and/or heavier flywheels/generator pulley ala the SOM is what you need.  The smaller the bulb wattage, the harder it will be to get the flicker down to tolerable.  The two tools available are adding rotation mass and electronic voltage regulation.