Whirlwind Saga Continues

[mmm]

It seems that taking 120vdc and converting it to 24vdc at this large of a wattage is about $1200.00 for transformers, and the heat that would be generated by the transformers is really a waste of power. One company I called said the transformers would burn up if the Hz fell below 40 regardless of the voltz.

Someone suggested buying 3 Arc welders to convert to 30 volts, Ill have to check prices on that? I wonder about efficiency?

I Know someone like Hugh Piggott might know how to possibly just rewire this PMA

Some of the later designs of this pma allowed a person to change pickup wires to configure voltage. I have a schematic that shows 3 sets of six wires and depending on how they are wired determined voltage, but this is a older version which doesnt have the wires labeled I was able to determine that the main 3 phase wires all have 3 coil wires connected to them which doesnt make sense compared to the diagram.

I know there has got to be some reason to all this. The magnets are in 3 groups of six magnets each, 3 coil wires to each phase and supposedly 18 wires all together of which I cannot easily find at this time. Maybe I actually have a different version and someone sold me literature to another model?

If I am to spend the money on having a crane put this genny up along with all the other wiring to change etc I would like to be able to get full power from it. For less then a grand a person can buy a genny that puts out 800 watts.

Is a set of three welders a good cheap way to go? How much line loss would there be?

It seems if the genny was cranking out full power the welders would be producing alot of heat and running fans which would account for more loss?

How hard would it be to figure out and change wiring to configure it to 32 volts?

Maybe this pma is going to spend alot of time on the workbench in the garage.

Russ, Colorado

[Ungrounded Lightning Rod]

It seems that taking 120vdc and converting it to 24vdc at this large of a wattage is about $1200.00 for transformers, and the heat that would be generated by the transformers is really a waste of power.

Yep, buying such transformers new would cost a bundle.  Yes the heat is a waste.

But it's not THAT much waste.  Transformers are very efficient.

One company I called said the transformers would burn up if the Hz fell below 40 regardless of the voltz.

He's confused - or playing CYA.

A transfomer rated for an input voltage of 120 at 60 Hz will do fine with an input voltage of 60 at 30 Hz and so on.

The issue with transformers is that the inductance is what limits the current - the resistance of the coils is deliberately kept small to limit losses in the transformer.  But if the current goes too high the core saturates - reaches maximum magnetization.  It's the CHANGE in magnetization that resists the current increase.  Once the core has reached saturation the inductance suddenly drops to about the inductance the coil would have if the core were gone - virtually none.  Now you have a very low-resistance hung across your input voltage.  If you're connected to a hard voltage source (like a power grid) the current suddenly increases drastically.  It's like you took the few dozen feet of heavy wire that make up the coil straight across the power line.  This makes for melting wires and insulation VERY rapidly.  And it's what the vendor is worried about.  So if you start talking about running below the rated frequency they'll start hearing alarm bells and tell you not to do it.

But you're NOT hooking the transformer across a hard voltage source.  You're hooking it across a permanent magnet alternator.  The voltage coming out of the alternator (neglecting resistive losses) is directly proportional to frequency, because IT was generated by the CHANGE in magnetic field from a CONSTANT STRENGTH moving magnet.  (An alternator is half a transformer, with the changing magnetic field provided by a moving magnet rather than the coil and half-core comprising the other half of a real transformer.)  Move the magnet fast, you get a lot of voltage for short cycles.  Move it slow and you get a little voltage for long cycles.  But because the voltage was created by a changing magnetic field whose maximum was a constant, the maximum magnetic field through an inductor driven by that voltage will ALSO be a constant, regardless of frequency.

(Or at least you would if you wound it with a superconductor.  Since you are using copper with a non-zero resistance, frequency DOES matter - a little bit.  If you go REALLY SLOW, the resistance will make the output current decay a bit, and as a result your peak magnetization in the transformer will be a little LOWER.  This is even better.)

[drdongle]

 I wouldn't panic yet. I think you need to concentrate on figuring out how the thing is wired, there are only a limited number of possibilities. Either the different coils for each phase are wired in series or parallel. Your description suggests that each phase is made up of 3 coils and I think that what I get from that description is that all the coils of each phase are in parallel. If that is not the case or your not sure then you need to find out for sure. This may take cutting some of the twine that is used to lace up the windings and further visual inspections as well as continuity checks.

 If series you could rewire to parallel dropping the output and volts and increasing the current capacity or they are in parallel in which case you could us a switching power supply to reduce the output to a voltage you can use. Many commercial units will take from 85 to 240 volts input.

If we all put our heads together on this we can make it work.

Carpe Vigor

Dr.D

[John II]

Hello Ross: I own a Whisper 900 which was made by the same folks that made the WhirlWind units. I bought a 3ph transformer from them that is made for their larger 3kw whisper rig for about $600 that was a few years back. That was a few years back. The Whisper series is now turned over to yet another company.

We run this 3 times oversized transformer on our Whisper 900 plant. With our plant, it's maximum wireable voltage is 48v, And we use the transformer to get to 24v or 12v our choice. It'll also do 120v to any over the lower voltages. Elliet Bailey (sp) Founder of WhirlWind told me that the larger transformer is much more efficient then if I had ordered the smaller one made for the Whisper 900. The point I'm trying to make is, if you have the proper transformers, your loss will be so small you won't even know it. At the time the reason I went with the larger transformer, is I could use it if I ever migrate to a larger wind machine. I wish my Whisper-900 were a 120vac unit, line transmission would be even better that way.

If you have enough iron in your transformers, they will keep their power factor, and transfer power at just a few hertz. If your blade is just barely rotating, you will be getting power. That's what your wind unit is after all... is a rotary transformer!

I'm not sure most welders would do the job ? A lot of them have output voltages as high as 90v so this would give you very little step down. Also the duty factor is inportant. You wan't 100% duty factor and most welders don't do that but at the lowest settings, and some don't even do it on the lowest settings. They just don't have enough copper or steel in them.

As far as purchasing the transformers, I think you can do much better than that. If you can't find the transformer just the right size, you can always parallel and series them just like batteries to get your proper output (within reason that is).

Here's an example here is a 120v to 12v 25amp output transformer for $20.00

(See URL at the bottom of this posting ) When I insert it here, it makes the rest of the posting in such a fine print no one can read it !

I notice they have 1890 transformers in that particular model... haha

All of the transformer 115v inputs would be wired to each of your WhrilWind's 120vac outputs.

You would have to wire two of the transformers output's in series to get your 24v output. So two of these transformers would be good for a maximum of 25 amps at 24v output.

Because 4000 watts divided by 3 = 1,300 watts per phase divided by 24v you will need transformers capable of delivering at least 55.5 amps per phase. Three sets of these transformers ( 6 transformers in all ) would give you 75 amp capacity per phase while you only need 55.5amps. Over kill is good, as they run cooler and more efficient.

6 transformers X $ 20.00 = $120.00 per phase X 3 for 3 phases would = $ 360.00 for total transformer cost.

This way you could re-wire the transformers easily to obtain not only 24v but even 12 volts and 48 volts.

Also you don't need to start with that many transformer sets to get into charging your batteries, if you have a means of regulating your unit from over speeding and shutting it down from the 120vac side. (If you have a control box) If you don't you would need to use all the transformers so you would be able to shut it down from the 24v side and you would need something like the Enermaxer charge controller or something similar to keep it regulated. ( I own a couple that I'm not going to use because of equipment changes that I might sell cheap)

There are probably other surplus sources for even larger 120v to 24v transformers out there, you will just have to look around. What I mentioned above was just something real fast off of the top of my pointed little head ! haha

Also Russ, If you have quite a transmission distance from your tower to your batteries, or if you plan on up grading to higher voltages, I encourage you to keep your 120v unit. But if you are planning on 24v only, I think I can get my hands on a mint 4,000 watt WhirlWind low voltage unit which I think (I'd have to check) is re-wireable for 48v, 24v and 12v. I might be interested in swapping with you as I'm now trying to set up a 120vdc system here. You would only need to swap just the generator head & you could keep all the rest (I think.)

As far as re-configurating  the wiring on your current unit, If you could catch up with one of the original WhirlWind dealers, they might be able to tell you, or at least refer you to someone that can tell you.

Last but not least option, you could take it to someone and have the generator re-wound with the correct wire size to get you to 24v which is easy to have done at almost any motor repair shop. They will have to cut a coil & count the number of turns and then check the square mill size of the wire (or weigh it). Then they basically will re wire with a 5 times larger diamenter of wire of the same weight. (someone correct me if I'm off here please.)

John II

http://www.surpluscenter.com/item.asp?UID=2004122717434785&item=15-1103&catname=electric

[iFred]

Really, what I would do, and this may be different from others. I would hook up a bunch of 12v batteries in series (10) and charge direct with a simple diversion/charge controller. Done. Simple, inexpensive and very efficient. Now some will disagree. there is a very good reason why that wind gen is at such a high voltage. and there is also a very large advantage to doing it this way. You would reduce your losses for line transmission and have a closer 1 to 1 ratio for inversion, this means you need less amps to do the same job. If you do a search for -efficiency- you will see that in prior posts we had talked about these issues. higher voltage is more efficient no matter how you slice it. You could put in a transformer, but why waste the power to heat, eddy currents and wire loss? Makes no sense and nothing a simple controller could not handle.

[John II]

IFred: What you are suggesting is what I'm working towards myself. It makes a lot of sense. But there are at least a couple of big hurdles by going to a 120vdc system. First I can find no commercially made 120vdc inverter for less than $ 6,000.00 and I have yet to find a 120vdc charge controller. I know there's gotta be one out there, but I haven't located one yet and I have been looking for quite a time now.

Other than that, a 120vdc system has as you said a lot going for it.

John II

[jimjjnn]

Check for Exeltech inverters. I believe they have reasonably priced inverters that start at 12 volt up to 120 volts and are very durable.

[jacquesm]

look around for scrap transformers

they're pretty common !

I picked up a 12 KW three phase for $50...

I use it to run my mill (which is 575) from a 460 genny.

[mmm]

John II: If I havent told you I have a 12kw Best M series inverter, it is both 120 and 240vac output. It is from the mid 80's and Bob from kansaswindpower.com told me it was only 80% efficient. I was just going to use to run my hot tub pump occaisonaly in the evenings off of my second bank of batts. But with all the info I have gotten from this site I have to make a few decisions. All I know right now is My backhoe will be back from a jobsite this weekend and I am digging holes for my 70 ft tower for this whirlwind whether I convert to 24 or keep it the same I dont know. If not we still might have a deal of some sorts. The only problem I can see is this inverter must weigh close to 400 pounds, maybe only 300

[mmm]

Look around? I spent 3 days online and lotsa phone calls?

Any websites?

Russ, Colorado

[jacquesm]

I asked a whole bunch of electrical contractors in my neighbourhood, one of them said if I could lift it I could have it otherwise it would be $50 to get out the forklift and dump it in my truch... I couldn't lift it...

[John II]

Hi again Russ: I'm quite busy right now, and will be for the next few days but it's possible that I might be able to locate a 4 kw Whisper manual (if you don't have one.) It might tell us something about the re-wiring pattern on your machine. Drop me an Email and give me your Email address ok ? Email: jjones2(at)inter-linc.net

John II