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Bryan's 4Kw motor Conversion Part 2 The testing
ruddycrazy:
G'day Guy's,
Well looking around my red gum forest I have found some suitable trees to make a set of blades but the question remains what length is required to get the beast to perform best.
Now doing test runs in my big lathe in 5:1 back gear along with the VFD programmed make make the 2HP 3 phase drive motor think it's a 3-1/2Hp one but when 240 volts is reached and it cutsin the VFD is complaining of over current and I used a 100 amp bridge rectifier and 2off 12 volt truck batteries in series I saw a glimpse of 89 amps on the current meter. So repeated the test four times and on the last test the bridge rectifier flashed out and let the smoke out.
Now as I do have a 16HP Listeriod it is time to give the beast a run to just what can it make and as the engine speed is 1000 rpm and under load around 900-930 rpm I reckon a 3:1 reduction so around 280 to 330 rpm can be reached. I do have to get a new bridge rectifier and this time I'll go for a 250 amp model and the load will be my 24 volt 735AH Forklift battery which powers my shed and who would think a washing machine motor and a few caps has kept this battery going.
As this was made a long time ago for the newer members I will describe this conversion
At work when I pulled off a motor from a gearbox it was saturated and had shorted out so it was a good candidate for a motor conversion, 4Kw flange mount so all the windings went into my copper drum.
I machined up a new rotor from an old warman pump shaft and as I was skewing the poles 10 degrees I counter bored a seat for each magnet and only broke one magnet and had a sore finger for weeks. Now 22 16x13mm round N50 magnets were used and as each magnet found home when i finished the pole was epoxed in then when all four poles were done I potted the rotor for the final pour and 3 weeks later machind the OD of the rotor leaving a 2mm gap on diameter from the windings.
After doing the one wire test I decided to do three in hand 1mm wire and brought out double delta with the windings, why bother with Star when Delta gives us more of what we want if the generator can handle it.
To insert the rotor I used a chain block on my lifting jib on my tractor where the motor was cased in a G sized warman pump housing on blocks, when it hit home the tractor jumped up and I thought what have I made here.
So it is time to test this project out and honestly as the motor conversions are bullet proof a down wind design where no tail is need is considering.
Cheers Bryan
Bruce S:
I was wondering about how many iron based items were on their way to those mags!
Cheers
Bruce S
bigrockcandymountain:
I've been waiting 10 years to see more of this conversion. I'll be watching your test with great interest.
SparWeb:
--- Quote --- So it is time to test this project out and honestly as the motor conversions are bullet proof a down wind design where no tail is need is considering.
--- End quote ---
With low-TSR blades and a site that doesn't have crazy hurricane winds, I think that's an excellent idea.
kitestrings:
I had the opportunity to work on a lot of downwind turbines, AC induction, grid-connected generators, some years back. There are a few trade-offs I'd say. They generally require a heavier frame because of the need to cantilever out past the tower, and because they usually use a horizontal mount, it can make slip-ring assemblies a bit more challenging. They also can get caught in an upwind position occasionally.
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