Hello! I'm thinking of buying a ST generator head for my Yanmar project and had a question for those of you who own and use a ST head. Here it is : If you had to buy another head, would you buy another ST head? Have you had good luck with it? Any problems? Would you recommend a ST head? By the way, my generator will be used as a backup generator. We usually end up using a generator, on average, a week total out of the year. We have had a few times we were out for a couple of weeks.
THanks!
Ben
I guess my recommendation would depend on your abilities and mental attitude toward maintenance.
And a little bit influenced by how much you want (or are able) to spend.
I think the ST's are great. But for a little more money, you can get a permanent magnet generator that
has no brushes. The only maintenance items would be the bearings. But you have to be more careful
around it. No welding, grinding or anything of that nature anywhere around it.
I have heard that the PM (permanent magnet) generators do not give the pulsing lights that the ST's give.
Ralph
Hi Ben
I have a ST-12 direct coupled to a Isuzu/ThermoKing C-201 4 cylinder Diesel. I bought it on E-Bay
already built up this way. I have had it for 5 years now. It is obvious that mine has never been apart
(No Tool Marks or chipped original paint) I use it at least 6 times as often as you describe... Plus whenever there is an outage.
The Dog House did have all the screws replaced over time, and the wires to the volt meter have broken long ago.
But... It still has the original Brushes and bearings. As far as the power it produces, Everthing runs the same as on the grid, No flicker, I have central air as well as a Small machine shop 2 Lathes (1Ph Small)
2 Mills (3 Ph Bridgeport clones) 1 Surface Grinder (3 Ph) Drill Press, Welder, Air Compressor. The 3 Phase equipment is operated Via Home Brew Rotary Inverter (Motor w/Cap Start). Note: the shop never has all equipment running at the same time, But very often we will run 2 thru 4 machines simultaneeously and can do so while on the genny.
All that said... I am not very impressed with the appearance of the unit. It definetly resembles its cost!
(CHEAP!) Frankly, I expected it to fail long ago. And I am certain it will, Probably when needed most!
Rob
I've got an ST5 with just over 1400 hours on it. It was used to power the construction of our off-grid home and is now doing duty charging batteries on cloudy days. Mine had the rectifier go almost immediately, the bearings go at about 100 hours and had a connection in the windings break at 850 hours. Since then there's been no trouble with it. ::) Fortunately it's been very repairable in the field so it's got that in it's favor. I'm now looking to replace it with a 3ph industrial motor to use as a dc generator to charge batts directly.
Thanks for your replies. I am fairly mechanical and I don't think I wouldn't be afraid of working on a generator. I've overhauled engines, transmissions, automobile generators and alternators, starters and such. I'm the kind of person that would rather fix something thats broken rather than buy something new. but... with all that said, I don't want this thing to fail me when I need it the most. I can live without lights, AC, TV, etc.. but the main reason we need a backup generator is for our freezers and fridges and to run the well. It only takes one major generator failure and your freezers of meat and other produce are spoiled. It would only take one major breakdown and you could buy a little better generator head. We do have a small consumer "screamer" generator that is getting some major time on it. I know that sooner or later its gonna fail and my guess is "sooner" rather than later. I've worked on it some and I know its not something worth fixing. Thus the reason for building this setup with the small diesel yanmar.
I have done quite a little reading about the ST heads and they all seem to have a few bugs. If I could buy one and before I even use it, replace the bearings with better quality sealed ones, replace with a quality rectifier, make sure all connections are good and know for sure that its not gonna fail me I would definitely go with the ST. Even if the rectfier or a brush failed while using it, I could live with that kind of breakdown. What bothers me, is if something goes wrong with the stator or rotor while using it that I couldn't fix. Something that would require a motor or generator shop to fix. Are these kind of failures common? I know that these kind of failures could also happen with a better quality generator heal also. Maybe I'm being to paranoid, lol, but I just want this thing to be as reliable as it can be. With that said, What do you guys think?? ST or no ST??
Thanks!
Ben
As a backup generator and given the amount you indicated you will use it, an ST should easily outlive you! The only thing that might bite you would be to lose the residual magnetism because of long lack of use or because you leave it connected when you shutdown your prime mover. So you would want to be well versed in how to flash the field should this ever occur. PMGs have the advantages previously noted (plus PMG would likely survive an EMP event if that's a real concern to you) but PMGs are also more expensive and have the issues previously noted.
I immediately got rid of dog house crap and just added a connector box:
http://listerenginegallery.com/main.php?g2_itemId=351
Bob B.
Tom Osbourne @ Central Georgia Generator has brushes, bearings, commutators and voltage regulators for cheap.
I have 5 rectifiers salted away. Tom's units are copper wound so the above are about the only parts you should need.
ST's are cheap, hard to kill and easy to fix in the field. If they aren't running, an EMP won't kill 'em.
Ron
Agree w/ sailawayrb & vdubnut62. I have a ST 7.5 w/ about 600 hours on it -- no troubles at all. I also have backup brushes & rectifier from Tom Osbourne. I don't expect problems, but I also keep a gas screamer in a container just in case the ST or Listeroid need something.
Marcus
Same here, have an ST-5 with about 150 hours on it. I replaced the bearings and doghouse and use a solid state rectifyer. Very easy to work on, and mine puts out pretty good power. I am looking at another, larger one to make a tractor PTO generator:)...
I've got over 4000 hours on an Utterpower ST-5. I took it apart when I got it, replaced the bearings and sprayed it with Glyptol. I've gone through a set of brushes and had it apart another time to clean it and repair a wire that was rubbing on something. It runs a pretty sensitive inverter once there's a load on it and has served me well.
Thanks, Geno
I have an ST12 with thousands of hours on it. It has been our primary powe since 2007. We live off grid without solar or wind supplement. All ourelectrical power comes from it. I have had to replace the brushes and of course replace the factory rectifyer with one fvrom Utter Power. Check out the Utter Power site for all the info on these you will ever need.
Thanks everyone for sharing your opinions and experiences! I have decided that I will probably go with an ST head for my project.
Thanks!
Ben
I have an ST-15, powered by a twin Listeroid. If I were to do it again, I would purchase a higher quality generator head. The ST-15's waveform is not great and looks like many of the pictures posted on these forums. So, mine's not worse, but I find it difficult to deal with. I cannot run some of the computer UPS' in my house on the ST generator. Yet, my Subaru 5500W genset does fine. My ST only produces 109 volts per leg. So I had to use a "special" voltage regulator that uses one of the 120V legs as excitation power. I'll bet that "special" regulator is easy to find in an emergency,,,not.
What I find interesting is that a higher quality unit is not that much more expensive $600 for the ST and about $900 for a "real" gen head. And, you don't have to deal with replacing bearings, brushes, applying glyptol, installing a better rectifier and voltage regulator.
Cujet,
Thanks for your input on the ST and for sharing your experience. I was curious what is the brand of the generator you can buy for $900 that is superior to the ST? Just curious as any quality brushless unit I looked at was around $12-1500.
Ben
I think the waveform quality that people experience from their ST is more a function of their setup than anything else. We know the Listers and Listeroids introduce a 5 HZ frequency because of the nature of their power stroke. We know the magnitude of this 5 HZ frequency is larger for the twins than for the singles everything else being the same. We know if you wire your ST for 240 (instead of 120) and one doesn't keep the electrical loads perfectly balanced (i.e., via a balance transformer) you will encounter voltage sag and often hear growing sounds. And than there are folks who get creative about "balancing" their Listers and Listeroids which has the potential of making the 5 HZ power frequency magnitude larger than it would normally be.
Bob B.
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
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
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.
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.
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.
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
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?
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.
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.
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
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
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
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
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
Your AVR is defective but CGG has a history of good customer service.
Make sure you let us know how it turns out.
Quote from: BruceM on March 26, 2013, 05:27:25 PM
Your AVR is defective but CGG has a history of good customer service.
Make sure you let us know how it turns out.
CGG is great to work with, looks like a new 7.5 kw ST will be on a truck coming my way. I agreed to send the bad one back and pay for shipping on it in exchange for a new one. Tom and Chris are excellent to deal with. ;D I hope this one will be ok, should be and I will let yall know how it works out.
Ok, the new 7.5 ST is mounted and running. The voltage output is stable and no more flickering lights. The only thing different now is this ST is very sensitive to an unbalanced load. If it becomes unbalanced more than a 1000 or so it watts is growls pretty good. Does running the ST in the growling state for an extended period do damage??? I have it wired for 240 vac output so it runs the hot water heater or range if need be during power outages. I installed a Reliance Gen transfer panel and can add or shed loads to keep it balanced. The small analog gauges on the panel indicate I have had approximately 5Kw on it and the frequency only dropped to 59 hz. I am pleased with the unit so far but the growling can be aggrevating. Any ideas how to correct the growling or is it inherent of this type of gen head? I will put up some pictures in the member project section in the next week or so. Also the little yanmar runs very good on used filtered ATF mixed with a bit of diesel fuel ;D.
growl is noise produced by parts that should not be moving, so I would avoid conditions that induce it (unbalanced loads). Maybe getting a balancing transformer and wasting 50 watts in it, is better than shaking the windings and lams loose.
Mike, could you explain this "balancing xfrmer" ??? in more detail. What is does and how it works??? Were to get one and are they expensive??? I would be willing to waste 100 watts if it will relieve the growling. I figured it was harmonic vibration of the internals of the ST, I wasn't going to let it do it for long as I figured it wasn't good.
I found this: http://www.altestore.com/mmsolar/others/PSX240%28900-0043-1%29.pdf
Could this be used for my application???
If you didn't need 240 you could wire it for 120 and it would always remain balanced and you would not have any growling.
If you want to quiet the growling, and you don't mind reworking the internals of the generator................
http://www.microcogen.info/index.php?topic=460.0
It is a lengthy read, but explains the BS-ST mod that separates windings in the generator, and reconnects them to pretty much cure growling.
Quote from: bschwartz on April 22, 2013, 10:53:44 PM
If you want to quiet the growling, and you don't mind reworking the internals of the generator................
http://www.microcogen.info/index.php?topic=460.0
It is a lengthy read, but explains the BS-ST mod that separates windings in the generator, and reconnects them to pretty much cure growling.
Awesome thread, I've bookmarked that one as a keeper!
I posted some pictures of my little gen set, it looks like most of the others so nothing innovative by me just found a lot of good ideas from this forum.
Here is the link to it in member projects.
http://www.microcogen.info/index.php?topic=3085.0
DRJensen, Yes, the special balancing autotransformer you linked to does look like it would do the job of always presenting your ST head with a balanced load.
Bshwartz's method of correcting the ST winding to better handle imbalanced 120V loads is brilliant. If I was using a ST head as home backup power for 240/120 I'd do that. I forgot to mention the growl on imbalanced loads in my earlier ST comments. It is a common problem.
It does makes you wish one of our enterprising US importers of ST heads would get them wired up that way to start with, along with quality bearings, bridge, AVR.
For my off grid use my ST-3 only generates 240VAC and I use that directly for well pump and I step that down via toroidal transformers to get 120V for my appliances and also step it down via Picaxe controlled motorized variac for my 120VDC battery bank charger.
I had not seen that Bshwartz method/thread before. That is indeed brilliant and a great way to handle a 240/120 requirement.
The autotransformer mentioned in the earlier posts does work :D. I saved up a few pennies and bought one. Now I can still have my ST configured for 240vac output and have a pretty good 120 vac imbalance between L1 and L2 and no growling from the ST. Now I can rest easy knowing that if a load like a hair dyer, iron or microwave is turned on the ST will not growl and shake if L1 or L2 has more load than the other. I appreciate the input Bruce, made spending the money easier knowing you guys know what your talking about.
DRJensen,
I have been trying to grasp the wiring for the PSX-240 setup in the Generator Balancing mode. As I read through the Outback links, I am confused by the wiring diagrams listing inverters. Could you point me to a web site with a good wiring diagram? I also have an ST 7.5 setup for 240VAC that growls from time to time.
So to start the discussion:
ST 7.5 has L1, L2, Neutral & Ground. When setup as in Generator Balance mode do both the L1 & L2 feed into the 25 Amp breakers? My objective like yours is to get 240 VAC balanced output. Any links or comments would be very helpful as I try to decide if I want to spend $300 to $400 for a unit. In the attached PDF file wiring diagram could I just connect to L1 & L2 = 240 VAC on the other side of the PSX-240?
Bruce
Bruce, I have a disconnect that my generator plugs into (50 amp outlet). I wired the PSX-240 in parallel with the generator. Were L1 and L2 is located in the disconnect from the generator, land one side of the PSX-240 to to L1 and the other to L2. There is a neutral terminal strip inside the PSX-240 and a grounding lug as well. To makle it simple connect the generator in parallel with the PSX-240, L1 to L1 and L2 to L2 and the neutral from the generator to the neutral bar in the SX-240. The PSX-240 is not labeled L1 and L2 but the is a 2 pole 25 amp breaker on it so connect L1 and L2 respectively. I leave the 2 pole breaker off until the generator is warmed up and ready for load I then turn on the PSX-240 and then turn on my transfer switch to the house. Now when the generator is balanced there is no deifference in potential across the transformer. When an imbalance occurs it applies current from the unloaded side to the loaded side to balance it and draw equal current from your power source i.e generator or invertors. If there is an imbalance of lets say 10 amps, the transformer draws enough current from the unload half of you generator and transfers it to the half with the load on it. All I know is now I can run my RV air conditioner or microwave or the wife can turn on a clothes iron and the ST doesn't growl anymore. I hope this helped as I am not an electrical engineer, I am simply a Combustion Turbine Tech for the local power company. I understand how to properly wire or install such a device but the theory sometimes is tuff to grasp.
Dave
Thank you for taking the time to write this up. Perfect. I was going to tear down my ST 7.5 and Glyptal all the internal parts. What I like about the laod balance transformer is that it solves the root cause of the problem. Now to start looking for the best price. Do you have an opinion about buying the version without the case to save a $100 ? Perhaps penny wise and dollar foolish thinking.