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Author Topic: st voltage regulator popped  (Read 13412 times)

Doug

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Re: st voltage regulator popped
« Reply #15 on: March 12, 2007, 02:30:25 AM »
Well just an Idea here but what do you think of dc suply with two dropping resisitors one pot for setting the base no load voltage and a second in paralel that uses a NPN power transitio biased from the recitified output of a CT wiried into the L1 and L2 from the head?

I know thia ia realy crude but I think it would work provided you kept the PF of the loads as close as practical to unity....

Doug
It's a Good Life, If You Don't Weaken

adhall

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Re: st voltage regulator popped
« Reply #16 on: March 12, 2007, 03:13:45 PM »
Doug:

It sounds to me like you want a constant current source to supply enough field current to give desired output voltage at zero load and some other circuit to add proportionately more field current according to the load current of the generator. And it sounds like you want to keep the electronics to a minimum.

I have limited experience and knowledge about CT's. I have only seen them used to transform a large current down to a smaller one for feeding an AC ammeter. However, if my memory serves me right, the CT basically acts like a current source.

If that's true, I am thinking you could use the rectified output from the CT to directly increase the field current. I am thinking of your idea of the DC power supply feeding the field coils through a resistor for the base current and then connecting the rectified output of the CT directly across the field coils. As the load current increased, the CT would output current that would add to the base current. The rectifier would prevent the base current from back feeding through the CT.

You would want to find a CT that outputs a little more than the incremental current increase needed by the field coils at full load. Then you would put a load resistor across the CT to tweek that in to the exact amount you need.

This avoids using electronics, except for the rectifier and the DC power supply. And you could simplifiy the DC power supply by using a constant voltage (i.e. ferro-resonant) transformer with a rectifier. That would eliminate the filter capacitor and electronic voltage regulator.

Do you think this might do what you want?

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

Doug

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Re: st voltage regulator popped
« Reply #17 on: March 12, 2007, 10:25:19 PM »
Sounds like were on the same page.....

Better idea driving the base of a single transformer like you say. Sort of like a class A amplifier. not much simpler than that I guess.....

Needs to be pondered a litle more...

I need to proof read my posts, some of these read like I'm drunk.

Doug
It's a Good Life, If You Don't Weaken

rmchambers

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Re: st voltage regulator popped
« Reply #18 on: March 12, 2007, 11:16:25 PM »
Sounds like were on the same page.....

Better idea driving the base of a single transformer like you say. Sort of like a class A amplifier. not much simpler than that I guess.....

Needs to be pondered a litle more...

I need to proof read my posts, some of these read like I'm drunk.

Doug

You're not?  haha.. just adds to the charm a little.

ronsmith

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Re: st voltage regulator popped
« Reply #19 on: March 15, 2007, 12:09:58 AM »
I bought the bridge rec. that Doug suggested from Radio Shack and mounted it to an old computer heat sink. Now for the fun part, can someone email me a wiring diagram to hook it to my Tawasi 12kw head. Mine had the potted resin type voltage regulater with a six wire harness on it. The six wires are 2 blue, one red, one white, two yellow. There are 4 large wires coming out of the head and hooking on U1, U4, U3, and U2. then there are some small blue wires, a small red and a small white wire. Please make it as simple as you can since my knowledge of wiring schematics sucks! Thanks :-\

Paul

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Re: st voltage regulator popped
« Reply #20 on: March 15, 2007, 02:44:53 AM »
Try this link.  You do not need that AVR for it to work.
http://www.utterpower.com/vreg.htm

Paul

db

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Re: st voltage regulator popped
« Reply #21 on: March 15, 2007, 07:18:44 PM »
Does anyone know the DC field coil resistance for a 12kW, 15kW and 20kW ST head?

Thanks
Dave

ronsmith

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Re: st voltage regulator popped
« Reply #22 on: March 15, 2007, 10:58:18 PM »
I think ihave figured out the wiring on my st head but I still need a few questions answered. First, which wire from which brush goes on the neg. and the pos. poles of my diode? Then where do I hook the the power supply for the volt meter on it?
     

adhall

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Re: st voltage regulator popped
« Reply #23 on: March 17, 2007, 06:21:57 PM »
Ronsmith:

It doesn't matter which brush connects to negative or positive on the diode bridge. Just connect one brush to positive and the other one to negative. In other words, the generator will work with the field connected either way.

As far as the voltmeter goes, the wiring depends on whether the meter reads 120 VAC or 240 VAC. If your meter reads 120 VAC, you connect it between either hot leg and the neutral. If you meter reads 240 VAC, you connect it between the two hot legs.

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

ronsmith

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Re: st voltage regulator popped
« Reply #24 on: March 20, 2007, 02:23:05 PM »
Problem solved. Installed a bridge rec. from radioshack mounted to an old pc heat sink. I ran for 5 hrs. sunday under a moderate to heavy load with no problems. Thanks to Doug, Adhall and the board for the help.  ;)

Doug

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Re: st voltage regulator popped
« Reply #25 on: April 08, 2007, 02:38:22 AM »
I think I have cracked the regualtor problem....

I stripped a 24 v Leice Nevil alternator: If I change the bridge, double the stator turns and Inow have a pilot and main exciter independent of the ST. Run the stock regulator off a 240 - 24 transformer and and I have a complete regualtor exciter combination thats made from common parts. The Z winding is now redundent, maybe I'll scrap the stock ST winding and make use of th extra slot fill for a better winding and insulation system.
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mobile_bob

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Re: st voltage regulator popped
« Reply #26 on: April 08, 2007, 03:03:16 AM »
Doug:

sounds like you got an st head

if so and you are considering scrapping the stator and rewinding it,, could i make a suggestion

bring out all the pole windings seperately,, i realize this is a butt load of wires but my thinking is
the st head configured with the poles in parallel might make a killer 24volt battery charger

5 watt @ 28 volts is one hell of a charger, and with a set of relays the windings could be regrouped for ac 120/240 as well
would make for a very versatile genhead in my opinion. or....

replace the Z windings with a set of battery charger windings, would be lower capacity i realize, but would make good use of the
slot space to do something useful i would think,, this would also make the genhead a bit more versatile.

i have somewhere a leece neville 2600jb, that i rewound years ago,, it will produce 480 volts at 2400 rpm,, the goal was 120 vac 60 hz at 600rpm
which i got to but the ampacity of the stator is around 7 amps,, not real useful... but it works it will power an angle grinder quite well.

i have an SD 5 kwatt 240 vac welding head that i got pretty cheap,, been thinking of rewinding it as well for a battery charger. i think i would like to split it
to maybe 2.5 kwatt 14 volt charger and 2.5 kwatt 120vac,, which would fill my needs quite well for most of the time except for laundry day.

post some pics of what you are doing,, am very interested in what you plan to do, and what you come up with.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Doug

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Re: st voltage regulator popped
« Reply #27 on: April 08, 2007, 03:30:41 AM »
Yes Bob I have an ST now....

I bought it from Altopro in Dorval PQ, nice fellow we came to a price and he shipped it last week.

Sadly I have some damage to the rear end bell, but I think we can get this cleared up in a few days ( pictures are in my putfile )..
I had thought of getting a new end bell machined if things go sour, but thats a lot of money for a very cheaply made machine.

Now If I'm reading you right Bob you want totake an ST and turn it into a giant 24v alternator?
Easy enough, just gut and put a 3 phase winding in it, jack the core densities to around 55,000 lines in the air gap and try and keep the iuron under 110,000. At these higher levels the harmonic distortion will be higher, but you won't care since your rectifing it any how. You should get another 10% more power this way ( Y config keep the turns down and a neutral to stop circulating currents.

I only have gut feeling on this but generaly two winding machines are a comprimise. I think a dedicated machine is a better choice since you need to use all that copper as efficiently as possible.

I think you would be better served to find an old transformer in the 2000 w range and strip it. Its a lot easier to spin coils and restack a core than you think, and they are a lot more efficient than a rotating machine trying to do two things at once.

Hammond made a lot of easy to strip and restack cores for GE and other companies years back to run industrial switch gear and odd ball stuff like that. Because these were low production parts with odd ball voltages ( like 4160 - 120 ) they were hand spun and bolted together.
You can also soup them up a bit by about 10% because your recitfying and building a charger so a little harmonic distortion isn't a concern

Doug
It's a Good Life, If You Don't Weaken