Author Topic: 10K ST generator head  (Read 10056 times)

GCHandy

  • Newbie
  • *
  • Posts: 11
    • View Profile
10K ST generator head
« on: July 01, 2008, 01:39:33 PM »
I have a question that I hope someone will help me out.. I have a 10 K ST generator head that I am only getting 109 volts at 60 hz if I go to 118 volts then the hz goes to 64 hz. It is connect to a Changa 1115  and running at 1800 rpm. I contacted George at utterpower and he said to put in a motor run capacitor, 1.5 uf, but when I went to get one, the parts guy  wanted to know what voltage?? I email George back but he has not answer yet . I am running the head 240/120 volts  so what do I buy?  Thank you for any help.

GCHandy

rcavictim

  • Certified Generator Head and Grand Master Sparky
  • Hero Member
  • *****
  • Posts: 1828
    • View Profile
Re: 10K ST generator head
« Reply #1 on: July 02, 2008, 01:26:50 AM »
With such a small capacitance value that won't do a thing hooked up across the power output lines, so George must have an idea that you'd place this capacitor across the excitation winding where it connects to the AC terminals of the bridge rectifier in the 'doghouse'.  That may boost the generator's DC field voltage just a bit.

In this location any capacitor rated at 220 volts AC or higher will be fine.  You could play with other values if you can find them cheap (3.3uF or 4.7 uF, 10uF).  Just be sure you are using a motor run cap, not a motor starting cap.  The starting caps are electrolytic and will blow up in short order.  You should not have to pay more than $7 for that 1.5 uF cap, and if you search you can find it for a lot less.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
- 1966, Petter PJ-1, 5 kW air cooled diesel standby lighting plant
-DIY JD175A, minimum fuel research genset.
-Changfa 1115
-6 HP Launtop air cooled diesel
-Want Lister 6/1
-Large DIY VAWT nearing completion

GCHandy

  • Newbie
  • *
  • Posts: 11
    • View Profile
Re: 10K ST generator head
« Reply #2 on: July 02, 2008, 02:35:21 AM »
All right that is what I needed thank you so very much. I do not know a lot about generators but I am learning thanks to all of you guys.
GCHandy

Doug

  • Hero Member
  • *****
  • Posts: 3386
  • Why don't pictures ever work for me?
    • View Profile
    • Doug's Petteroid Stuff
Re: 10K ST generator head
« Reply #3 on: July 02, 2008, 03:03:14 AM »
Make sure you follow his directions and don't improvise, goo dway for a Newb to get injured.

Not sure what he ( George ) told you to do could you post his instructions?

As  RCA said I believe he wants you to put it in the field and NOT across the L1 l2 leads.
It's a Good Life, If You Don't Weaken

oliver90owner

  • Hero Member
  • *****
  • Posts: 861
    • View Profile
Re: 10K ST generator head
« Reply #4 on: July 02, 2008, 06:55:19 AM »
Beware when buying capacitors.  AC refers to ability to operate with either polarity.  Voltage is, I thought, peak working voltage the capacitor will withstand.  Those two values can not always be put together as you will need 1.414 times the rated AC voltage (if using sine wave alternating voltage).  Ie. voltasge ratings are for DC.

I am sure someone will correct me if things have changed from 40 years ago.

Regards, RAB

Geno

  • Sr. Member
  • ****
  • Posts: 296
    • View Profile
Re: 10K ST generator head
« Reply #5 on: July 02, 2008, 11:10:36 AM »
Good source for run capacitors.
surpluscenter.com
http://surpluscenter.com/sort.asp?UID=2008070205013540&catname=&byKeyword=yes&search=run%20capacitor

I just bought 3 for testing.  A 1, 1.5, and a 2 mfd

The AC voltage shouldn't matter as long as its greater than your gen output.

Thanks, Geno

Doug

  • Hero Member
  • *****
  • Posts: 3386
  • Why don't pictures ever work for me?
    • View Profile
    • Doug's Petteroid Stuff
Re: 10K ST generator head
« Reply #6 on: July 02, 2008, 05:06:20 PM »
Motor run capacitors are rated in AC volts. Rating them in DC volts makes no sense. In any case, it will say on the cap what it is and if it is AC or DC.

Jens

You never know what your going to find in a box today....
Is it oil filled, electrolitic, tantilum foil who knows?

often you will find two different AC and DC ratings on Capacitors.
Sometimes you will find a pair of DC electrolitic caps back to back in an AC circut ( because thats all they had I guess ).

You just never know Jens lol

My Old boss George told me when he aprenticed as winder in Germany one of his firt jobs was to spin up foil and paper cores and pour tar in cases to make caps. Then he moved onto oil caps and soldering the cans, then he spun coils and so on Progressing to more difficult and skilled jobs in the trade.
The he came to Canada a worked as a pin setter in a bowling alley, its a funny old world....
It's a Good Life, If You Don't Weaken

GCHandy

  • Newbie
  • *
  • Posts: 11
    • View Profile
Re: 10K ST generator head
« Reply #7 on: July 03, 2008, 03:13:45 AM »
Here is what George wrote me,
It takes just a small amount of capacitance on the AC side of the rectifier to boost the voltage. Start with 1 or 2 uF and go up slowly. Make sure you're using motor "run" caps on AC. I think I settle on 1.5 uF on my ST10. Gives me 129v at 62 Hz (perfectamundo!)
Joel from ( powersoulutions)

To boost voltage, the cap goes across the harmonic winding - in
parallel.  Just connect the cap to the AC
terminals on the rectifier. Start small, couple of uF at most.
The parts guy just wanted to know what voltage I wanted and I did not know, thanks to every one for their answers
As soon as I can get back to the shop to do some work I will put the cap in.
GCHandy


 

Doug

  • Hero Member
  • *****
  • Posts: 3386
  • Why don't pictures ever work for me?
    • View Profile
    • Doug's Petteroid Stuff
Re: 10K ST generator head
« Reply #8 on: July 03, 2008, 03:48:37 AM »
Ok that makes sence.

Try it, get the cap at an electronics suply store and follow directions.
It's a Good Life, If You Don't Weaken

Stan

  • Guest
Re: 10K ST generator head
« Reply #9 on: July 03, 2008, 05:29:15 AM »
From my point of view Jens, no one presently around where you live knows what they are talking about, especially when it comes to politics.  :P
Stan

Doug

  • Hero Member
  • *****
  • Posts: 3386
  • Why don't pictures ever work for me?
    • View Profile
    • Doug's Petteroid Stuff
Re: 10K ST generator head
« Reply #10 on: July 03, 2008, 04:28:33 PM »
That's a very small Cap Jens....

Odds are only an electronics place will have something close with around a 100 volt rating.

And lastly, I would sugest fusing the the from the Harmonic winding to all this crap downstream at around 3 - 5 amps just incase something shorts.

My local distributor is an Abra electronics agent and electrosonic.
Doesn't mean they stock anything or understand what I want but they can get it
It's a Good Life, If You Don't Weaken

Petersbpus

  • Full Member
  • ***
  • Posts: 111
    • View Profile
Re: 10K ST generator head
« Reply #11 on: July 03, 2008, 10:16:28 PM »
Handy,
I'll be interested to see how that turns out, non conventional use of caps I know nothing about,
But My ST head only put out 104\208V no load, not good.
I knew nothing of caps, so I tried voltage stacking on the +DC brush to test if the added volts increased VAC
Added first a 6VDC dry cell in series before the brush then my 12 start battery right in series,
That proved to me it was the answer, my winding was either short of wraps or some were shorted and not giving the crappy Chineese rectifyer enough input volts.
I killed two birds and installed an AVR.
Bob
Listeroid 6/1 in progress
Alllis Chalmers 60KW 3 ph
Changfaoid 12KW w/  auto shutdowns, modern AVR and panel
2nd Changfaoid 12KW Marine conversion w/ full auto shutdown and remote panel
Changfaoid 7.7 hp driving 5kw alternater /inverter,
other diesel gensets bought fixed and sold

cujet

  • Hero Member
  • *****
  • Posts: 836
  • Lister power rules!
    • View Profile
    • www.cujet.com
Re: 10K ST generator head
« Reply #12 on: May 19, 2011, 03:55:01 PM »
Ive got a ST-15 head that's low on voltage. I like this idea very much. Any thoughts on what cap to purchase for an ST-15?

Thx,

Chris
People who count on their fingers should maintain a discreet silence

38ac

  • Hero Member
  • *****
  • Posts: 1605
    • View Profile
Re: 10K ST generator head
« Reply #13 on: May 20, 2011, 02:08:04 AM »
Chris, The books that came with my two ST heads from Tom Osborn have diagrams to put a reostat in the excitation loop. I see that the current lot of heads he is selling have then as standard equipment. You might give him a call to see if he has some pares?
Butch
Collector and horder of about anything diesel

ronmar

  • Hero Member
  • *****
  • Posts: 1225
    • View Profile
Re: 10K ST generator head
« Reply #14 on: May 20, 2011, 03:18:26 PM »
The models with the rheostat are wound different, and provide a little extra field excitation, which the rheostat limits slightly to throttle the field to put the output where you want it.  If the genset dosn't have it to begin with, a rheostat would only lower it more...

Some electrolytic filtration capacitance put in circuit right after the bridge rectifyer will increase the output voltage. Electrolytic caps are used for DC filtration, and are NOT used on motors, so you will find them at electronic supply sources.  This is pulsed DC voltage at that point(a real ugly waveform) that the capacitance will flatten right out into something resembling actual DC.  This capacitance reacts with the inductance in the windings, and the smoother more stable DC input to the field increase the efficiency and generator output voltage.  It also cleans up the output waveform a bit.  If it were me, before I did anything, I would run down to radioshack and buy the largest bridge rectifyer I could find and take the original one out of circuit.  A weak or bad diode in the bridge rectifyer or a bad electrical connection in that circuit could limit your field current and the output voltage.

If the rectifyer isn't the problem, The voltage at the output of the rectifyer is only about 70V peak, so you need around 75V electrolytic caps.  I have used 50V ones successfully on my ST-5, as the peaks are very short in duration(average voltage of the signal is below 50V).  You probably have an amp or so of field current unloaded, and perhaps as much as an amp additional for each 2KW of electrical load.  Based on that, I would start with 1000 Microfarad(uF) per amp of field current.  The ones I use are about the size of a D cell battery with two screw terminals on one end, rated at 1200uF each.  They work like a battery, and take in the pulsed DC(charge) and discharge slower, averaging the pulses into a very flat waveform.  Because they work like batteries, they are polarity conscious, and one terminal will be marked with a + or POS symbol.  The caps are installed in parallel which in capacitors adds their capacitance together, much like the AH capacity in batteries is additive when batteries are wired in parallel...   
PS 6/1 - ST-5.