Transformers, custom transformers, Winding transformers

[k0balt]

Thought that my research might be of use to others....

Building a 100A 16-32v charger, winding my own transformer.

I'm in the process of building a good sized charger, and have the good fortune to be living in a country where winding transformers, motors, and generators, as well as building  inverters (trace DR series copies, mostly) is done commonly by many small 1 man shops located throughout the towns, villages, and cities.



As such, it has been relatively easy to acquire the info and materials required.... and it strikes me that this might be of use to other members. I could have just about anything wound here, at a cost similar to an off the shelf unit. Is anyone needing unusual transformers?

as for my project, so far:


3.6kva core
8 lbs copper magnet wire
nomex paper
wire varnish
nomex sleeves

Cost to build a 3.6KVA (parts only) 80 - 260v to 12-40v  (100A or 200A, depending on voltage) transformer, approx $150USD.


Anyway, I'll update this thread as work progresses....

[k0balt]

  IIIT LIIIIIIVES...........




4 hours later....




Tech Stuff:

3.6KVA

Dual 14ga Primaries:
110v and 80-154v , step 10v for universal voltage 80 - 154 and 190 - 264 v operation

Secondaries are 120+A rated, 5ga  (no fun to wind these!)
2 ea 16v and 2 ea 2v, for 16,18,22v (200A) and 32,36,40v (100A) configurations.

Assuming normal or low input voltages, switching the primary to higher voltage windings gives 4+ 1.2v downward output steps and one 1.2v upward (more steps with a reduced duty cycle) output step.

This gives a fine grained range of 11 - 23v at 200A and 27-41v at 100A.

To this manual (switch based) control, I will be adding an triac circuit to give fine grained voltage and current limit control. With this I will be able to go from 0 - 41V 100-200A with full current limiting control.....

More to come.

[k0balt]

Any of you gurus out there...

Anyone else looking for a "swiss army knife" transformer like this? It could also be used for buck / boost, making an inverter, welding (in a pinch), and other uses. I am considering designing an even more "universal" design, as I live on my 50' schooner  http://sailfreespirit.blogspot.com/ , and one never knows what one might run into in the dark corners of the world.

Is there a need for 3 phase txformers for the homemade windmills, say 12v-24v, 24 - 240, or something to give a different impedance match for tuning?  It would be fairly trivial to make these, in the 2.5kva range.

Anybody interested in a 3rd world transformer construction guide?

[bob g]

yes i would be interested in an instruction guide!

are you able to post such a guide as a pdf, or email it?
or are you planning on selling it?

in any case i am interested

bob g

[ghurd]

Wow!
Only 4 hours!

I am not teasing, that looks like a project that would take a month.
Nice job.

Most people would be worried about how the lamination material reacts at varied frequencies.
G-

[k0balt]

good point, ghurd, the frequency would not be a nice stable 50-60hz for a wind generator. have to look into the ramifications of that....any idea of the cut in (lowest significant power transfer) and max frequencies that would be likely?

[Flux]

Most wind turbine frequencies will be low at cut in. Typically something under 15Hz. This means you need a lot more turns per volt to stop core saturation.

Upper frequencies will not be a problem but the excess turns may mean more leakage reactance at full load and the higher frequency.

So much depends on the method of loading, ideally the speed and volts rise together and the transformer is happy but some conditions of loading may mean a large transformer for fairly low power handling.

Flux

[bob g]

i am still interested in a 3rd world construction guide!



bob g

[k0balt]

Bob and others that might be interested in a construction guide.... I have had great success with my first unit, and am about to build another (a 240 - 120 isolation transformer) . This time I will be carefully documenting all the steps, and will put together a guide for all, free to the otherpower board.....do not despair, when i build it, it will come.... ;-)

Yeah, the low freq could definitely make things dicey....I'll be thinking on that one.

Also for interested parties, I'm about to post on DIY inverters.....as seen here in the DR.