? for those of you with an ST generator

[DRJensen]

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.     I hope this one will be ok, should be and I will let yall know how it works out.

[DRJensen]

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  .

[mike90045]

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.

[DRJensen]

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???

[sailawayrb]

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.

[bschwartz]

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.

[mike90045]

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!

[DRJensen]

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

[BruceM]

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.

[sailawayrb]

I had not seen that Bshwartz method/thread before.  That is indeed brilliant and a great way to handle a 240/120 requirement.

[DRJensen]

The autotransformer mentioned in the earlier posts does work  . 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.

[Horsepoor]

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  

[DRJensen]

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

[Horsepoor]

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.