Do many run their ST heads at 220 ? . When I first received my head I tried it on 220 but with the slightest unbalance it would object loudly, so I went 110 with no problems but now have just gone 220 on my cloths dryer and would like to use the gen on wash days.
I have no objection to the loud groan if it is doing no harm, but it sounds as if it is loading the bearings or in some way doing damage :'(.
Has anyone used their head like this and had no problems or is this a bad idea.
thanks Staggley
I cant tell you how harmful it might be or not, but I dont like to listen to it. Unless the load on both legs is balanced my ST 5 protests as you describe. For emergency supply to the house I could get by with twinning for all 110 but I need 220 back at the shop where the generator lives. It would be nice to have switch gear that would make the change over handy. Maybe the electrical gurus can give advice on what can be done in that respect.
Some have found that the set screw under the lifting eye in the top of the generator is loose & this has caused a groaning or vibrating noise in thier gen sets, it's something to check.
Scott R.
Thanks Scott I will check but it is fine even at full load on 110 so I think it is the unbalance.
Try using a balancing transformer to even the loads between the two 120v legs.
Prior to switching to a permanent magnet head, I tried one briefly on my ST-5 that not only groaned, but also had HUGE voltage differences between the highly and lightly loaded legs. I was never really happy with the ST-5, but the transformer helped a lot.
A step down transformer for your 120V loads would solve the problem. Check on ebay, they're not too bad.
Have you ever tried a mechanics stethescope to try and determine exactly where the noise is comming from. If it is not a bearing or internal contact issue, which it probably is not, and the output voltages and waveforms are acceptable, I wouldn't think there should be any problem running it.
my st7.5 at times after startup will put out a medium frequency whine that is much like a siren,, ear piercing
that can be heard from down the block it is so loud... its about a middle C on the piano or organ.
actually my wife has an electronic pitch thingamabob that she tunes her guitars with, maybe i can get a beat
with it and determine what the frequency is. i may be wrong but it seems higher than 120 hz and is definetly
higher than a 60hz buzzing/humming sound.
usually does this on cold days, when the load is just put on the head, it doesn't seem to matter if i am drawing off
one leg or the other, or both evenly, although it will shift the frequency just a tad.
i attribute it to a loose lamination or something like that, figure to look very hard at the stator core
when i tear the unit down for new brgs before i place it into service.
bob g
I have 2 st5 and they both will growl a bit if I'm using 1 side. Both have new bearings and good gyptol job? It's not bad but you can hear it.
I guess I am just trying to get my head around what may be causing this, it seams that most think its either uneven bearing load or loose windings either will in time damage the head ??? so I think it will be best to use a step up or down transformer. Thanks for all the replies.
Potter
For load balancing, I used a transformer, but it didn't step up or down. I hooked up the 240 side (two hots and neutral) of a 480/240 buck boost transformer. It was hooked up in parallel with the rest of my loads. That's it! The other side of the transformer was left disconnected. I still had two 120 legs or 240 for my other loads. It made a huge difference.
Someone from the LEF had these diagrams. I'd like to give credit, but don't remember who it was, I just saved the link. http://www.weirdstuffwemake.com/sweetwatergems/geek/images/balance_xformer2.jpg
I picked up a similar 3K transformer on ebay for under $100 that did the job.
....that was MacGyver..... ;)
Good going Bschwartz. There is no need to hook up the neutral on the ST side, though obviously it's working OK with it. Pity the ST's do so poorly with a load imbalance otherwise.
Your engine is too quiet. You need a louder engine. Then you will rest easy as you will not hear the laminated core growl any more. May I suggest a Dursley Lister air cooled?
TimSR2
You got that right Tim, my SR2 is LOUD!
I have the same problem with my ST5. Nice and quiet in 120v mode heavily loaded, but the slightest imbalance in 240v mode and it growls real bad. The set screw was loose on mine but it wasn't the problem. I even tore mine down and checked the bearings but they were fine, nice quality sealed bearings. The see-sawing voltage is driving me nuts and the only reason now I haven't powered my house with it. I was thinking about hooking up a computer power supply in 240v mode to try and balance the voltage and give me 12v volts for accessories, if that doesn't work I'll try a transformer.
Quote from: potter on November 17, 2009, 04:18:25 AM
I guess I am just trying to get my head around what may be causing this, it seams that most think its either uneven bearing load or loose windings either will in time damage the head ??? so I think it will be best to use a step up or down transformer. Thanks for all the replies.
Potter
If I knew exactly what physically was creating the noise, I could better decide how much to let it bother me. My reasoning is that some mass must move to create sound waves. If that happens to be wires moving then I am concerned about fatigue breaking or insulation wearing and shorting or grounding. If it is just laminations maybe not so bad. I have inquired about having my st 5 dipped and baked but the price quoted is $150.00 Can. I have planned to pull it down to install a set of 1st rate quality bearings and have a better look around. The original bearings dont sound bad but there can be a heck of a difference in internal finish and life expectancy in a Timken, SKF, etc. and an offshore "will fit"
That Likely will not happen till spring now but it likely wont see 50 hrs service in the meantime. No ideas on a handy way of quickly switching between fixed 110 and 110/220?
Has anyone seen a coil arrangement plan of the ST? This is strictly armchair engineering on my part, but I believe I remember Mobile Bob describing the stator windings as being 4 in number with only 4 terminals brought out and the other ends joined between pairs. My though is that perhaps coils side by side are joined to create a 110 leg instead of pairs from opposite sides of the stator frame. One arrangement would be unbalanced the other not. Could connecting of the coils differently conceivably end the growl?
Dunno
Use a clamp amp meter to check the load and then turn stuff on or off to balance the load, not to fancy or scientific - but it works, keeps the growlin' down to a minimum. Pumps and A/C units work really well for this kinda stuff.
Cheers, Fred
If you are sitting beside the generator perhaps you can switch the loads around but not possible when access to the loads is 200ft away.
Even if the annoying noise was assured not to be harmful, a reasonable electrical balance would be desirable of course, but we have not nailed down why some brands and constructions seem free of this habit.
We still have no takers on the suggestion that perhaps different choices in internal coil connection might eliminate the hum and achieve mechanical balance side to side of the rotor even if the two 120 legs are not electrically balanced.
I am inviting conjecture on possibilities.
Crofter, would this help at all if you don't already have it:
Out of the:
ST Series Single-Phase AC Synchronous Generator Manual (PDF)
BTW, should I post the manual to the white papers ???
Quote from: dubbleUJay on December 04, 2009, 06:22:38 AM
BTW, should I post the manual to the white papers ???
I know of no reason not to.
Thanks WJ; that is the schematic but not the physical layout of the actual windings. In all honesty I know just a little more than enough to get myself in trouble here. I have done a bit of going in and severing semi permanent internal connections in motor coils to bring out both ends for direction reversal and voltage change reasons etc., but have not had the ST5 apart enough to see if the stator windings possibly have accessible centre taps in each 120 leg. In the meantime I can listen and wonder what makes it tick (growl in this case, lol )
Here we go guys, the ST manual:
http://www.microcogen.info/index.php?topic=412.0
Sorry Frank, I don't own a ST so I cant help any further, there are more connection diagrams in the manual that might help, I don't know ???