? for those of you with an ST generator

[tinkerer]

Bob, thanks for sharing your input on the ST powered by the listeroid. I too was wondering if the unsteady frequency could be caused from the slower speed of these engines. I would imagine that as slow as they turn, there is a little slow down and then speed up between power strokes. I will be using mine on a little Yanmar that I plan on running around 2700rpm or so. I would guess that the frequency would be a little steadier with this type of engine.

Ben

[vdubnut62]

You won't have any flicker with that setup.  I'm direct driving my st12 at 1800rpm from a changfa clone. I don't have flicker, nor do I
even try to balance loads. I am very happy with the setup.
Ron

[sailawayrb]

Ben, your explanation of the Lister unsteady frequency is indeed correct.  For a Lister, this 5 HZ unsteady frequency is half the operating frequency (600 RPM or 10 HZ).  As a thought experiment...if we were able to operate our Listers at 1920 RPM, the unsteady frequency would increase from 5 HZ to 16 HZ, which is about the highest frequency humans can perceive flicker.  

http://en.wikipedia.org/wiki/Flicker_fusion_threshold

Like Ron indicated, you will not experience any flicker operating your Yanmar at 2700 RPM with a ST.  I have yet to replace the bearings, brushes, or rectifier that came with my UtterPower ST5, however, I keep spares handy should I ever need to do so.

Bob B.

[akghound]

My ST12 spent most of its live outside unsheltered. It ran during the heat of the summer and the sub zero of winter. So far all I have done is replace the brushes. I powered it with a 20/2 at just over 700 engine RPM. At that rate we had very little flicker with it wired for 120 vac. There was more flicker at 220vac and I did have trouble with balanced loads. However that never seemed bother the gen head.
Soon it will be powered from the crankshaft PTO (front) of a Kubota L275 tractor. I plan on running the engine at 1800 RPM with 1-1 pulleys/belt.

[playdiesel]

I dont have the hours of ST experiance that the other posters have. I do own two of them, a 5KW powered by a 6/1 clone and a 15KW on a 1115. Both are used as grid back up and we occasionaly run them on weekends to burn up our waste oil. Mine are both A-1 as for the quality of power produced in my opinion. Flicker you must remember is a product of pulses from the driver.  My 6/1 has enough flicker that was I do be off-grid I would add mass somewhere, engine or generator shaft in an effort to get rid of most of it, for back  up I will live with it. As for the 15KW 1115 set up my wife cant tell it from grid power other than she can faintly hear the engine running out back. Mine are both wired for 220 making it easier to switch back and forth from the grid. Both are are making between 122 and 126 volts per leg at 60 hertz with no other regulation. We moved some things around in the breaker boxes to balance the loads better but other than that 220 operation has not been a problem for us. We can run anything we run on the grid when running the 15KW unit. Of course when we are running the 6/1, usualy over night  we must manage what we run. It seems the ST heads are like the Indian engines? Not all created equal. If you get a decent one to start with they will make a darned fine head if you spend just a bit of time improving it before you put it in operation. I have done the junction box mod to mine and had the end bells off to resolder the connections and repack the bearings.  Mine both came from Tom Osborne, great service.

[tinkerer]

Playdiesel, I'm glad to hear that you've had good luck wiht your ST heads from Tom. I bit the bullet and ordered a ST 10 yesterday from him. I'll share some pictures when it arrives.

Ben

[mbryner]

When I bought my ST from Joel Koch (Portland, OR), the doghouse was already removed and it had a new internal rectifier.   I think the bearings were better bearings, too.   Does Tom Osborne buy his ST heads w/ the mods, or does he do some mods like that, or do you have to do them all yourself?

[sailawayrb]

My ST5 was from Joel as well.  I believe he was an associate of George from UtterPower at the time I purchased it in 2005.  Again, just put it into operation as delivered (except for the red paint job to match 6/1) and I have not had any problems to date.

Bob B.

[playdiesel]

My STs are two years old. Last I knew Tom now has at least two, maybe three different versions of the ST in the popular ratings. One of them is just your basic ST like mine. Then he has some that are factory equipped with rheostats, digital meters and a few other improvemnts. As far as I know all of them have iron fans. Best to call down there and ask, both Tom and the other fellow (name escapes me) are first rate and will answer all the questions you can come up with.

[tinkerer]

When I ordered from Tom, he told me the ST head I was getting had metal fan, sealed bearings. It also has the western rectifier. It also is coming with an AVR that he is installing. It does still have the analog voltage meter.
Ben

[vayidaho]

This site should remain as a permanent site, since the ST heads will be with us for many years, and apparently, they are continuing to evolve.  My first was a 7.5 copper wound ST running on belts from a Changfa. Since I could never figure out how to make it safe by building belt guards, I traded it. But it did run, although the Changfa was a pig.  My second was a 5KW copper wound ST running through Lovejoy L110s from a 3600 RPM China diesel with the 1800 output from the camshaft drive. A factory option. I replaced the bearings with sealed units before energizing.  It ran fine for a few years until I blew the engine and traded it.  My current project is an aluminium (sic) wound 3KW ST running through Lovejoy L-110s direct from a custom made flywheel adapter from a Yanmar 2TNV70-HGE bought from Burden surplus.  I will post more information as I discover the problems.

Tom

[DRJensen]

I built a Yanmar/ST7.5 and I am experiencing flicker on one leg of the output. Long story short, Tom with CGG and I determined that the harmonic winding didn't produce enough voltage and it would degrade as the generator warmed up. Tom sent me a 115v AVR and it is fed from L1 and then rectified to feed the field. It does work well like this but any light source in my distribution panel being fed from L1 has a flicker on it. I placed a fluke meter on both L1 and L2 with L2 having 62 hz at full speed no load and a funky frequency on L1 ranging from 55 to 85 hz give or take. It seems that the AVR is pulsing back into L1 causing this flicker. I know the output is steady because speed is not changing. I placed a 5uF cap across L1/neutral and it clears it up but boosts the voltage and I cannot get it low enough with adjusting the pot on the AVR. Anyone experience this or have any suggestions on how to get rid of the flicker?

Thanks, Dave

[BruceM]

Hi Dave,
What RPM is the engine running at?  I'm used to "Listerflicker" but assume your Yanmar is running at say 2300 rpm?  That makes the flicker more unusual.

I've not read any other folks having this problem with CGG AVRs, so something is fishy.

The AVR pulsing could be distorting L1 enough to get your frequency meter confused.  The AVR is also confusing itself, since it's regulating the output based on the voltage of L1, which it is distorting, and the capacitor is screwing up the AVR's  non-RMS voltage measurement.

However, the AVR current pulses on L1 should not be significant enough to cause flicker on incandescent bulbs.  If you switch the AVR over to L2 and the same thing happens there, you've confirmed that it's your AVR with a serious problem and not a winding problem on L1. 

Flicker on incandescent bulbs would be more likely by caused by problem in the AVR; it seems it's AC to DC voltage conversion has an EMI problem or some other instability.  After moving the unit to L2 and getting the same results, I'd want a replacement AVR.

I'd see if CGG has an AVR that can handle 240VAC input for excitation and regulation.

If you're stuck with a 120V AVR  I'd use a 240 to 120VAC step down transformer fed by L1 and L2. Choose a transformer with a VA or Watt rating of at least 4x the rated field coil volts times amps. 

Regulating off of one leg of a center tap 240VAC output is a bad idea, I think.  But it's not the cause of the flicker.

I avoid the problems of AVR induced distortion on my homebrew AVR for an ST-3 by using a step down transformer for excitation, a separate tiny transformer for sensing the 240V voltage, and "soft switching" bipolar power transistors to reduce interference on the 240VAC output.

Best Wishes,
Bruce

[DRJensen]

Thanks for the reply Bruce. Yes I have tried it from L2 as well and it moves with the AVR. I have also removed the AVR and it goes away. I also recieved a Rheostat that the unit might have come with and I cannot get the voltage down far enough with it (150wattx7.5 ohms). The output voltage from L1 and L2 is around 160VAC with no regulation. I expect the rheostat was sized for excitation from the harmonic winding  . I hate to keep throwing money and time into this ST generator. I just need to be able to get excitation voltage regulated down and rectified. If anyone has any more ideas please contribute.

Thanks, Dave

[BruceM]

Your AVR is defective but CGG has a history of good customer service.
Make sure you let us know how it turns out.