does tranny winding wire shape affect performance ?

Round wire does not pack as tightly (tesselate) as triangular, rectangular or hexagonal wire might, so going with round wire does have a cost.

I believe some applications go to the trouble of using other crossections - the only example that comes to mind are Bittner magnets, where the current carrying path is made of helical sheets with holes in the them - the cooling water takes the short path through the holes, while the current takes the longer, spiral path theough the sheets of copper.

-- Bill Sloman, Nijmegen

I am familiar with square or rectangular wire for winding voice coils, as well as flat aluminum ribbon voice coils.

greg

Increased leakage flux being one cost.

Large utility transformers (and generators) are wound with square/rectangular conductors.

When the new Australian Synchrotron (6km from here) was nearly finished, they had an open day, and I noticed that many of the beam-bending electromagnets used square wire, or square tube perhaps, perhaps 10mm on a side, with rounded corners. Each wrap was separated by a 10mm air gap as well, and I think adjacent turns were also separated. All presumably for cooling while 1000's of amps were pumped through them.

Clifford Heath.

Could well be tubing with chilled water, or LN2 pumped through them.

And for some applications more, copper surface area which can be important. Also at a 4 to pi ratio.

No, certainly not enough to make your own round wire square. But for the big boys (GE, ConEd, etc.) where a 2% return in efficiency is the difference between howling at the moon or a big fat christmas bonus then, yes.

I doubt any real cost benifits could be found in anything under 10 kilowatts in size. Are you trying to wind a 50 kilowatt toaster? trading silly questions here.

Spacing the turns by the wire dimension maximises the maximum impedance of singe layer coil - a bigger gap decreases the inductance more than it decreases the parallel capacitance and a smaller gap doesn't increase the inductance as much as it increases the parallel capacitance.

I'd expect water-cooled coils to use the Bitter geometry - a spiral ribbon to carry the current between two coaxial non-conducting tubes to carry the water with holes through the ribbon so that the water could flow straight along the tube,

-- Bill Sloman, Nijmegen

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toaster?

No, just curious.... when i read about tranny discussion and how or why someone might go to the trouble of solving various problems in tranny winding ? what kinds of problems are there and what are those solutions ?

In this case it might have been better to ask what parameters of transformer operation are affected by the airgap between windings and or how the windings are laid out including the performance and parameters affected by the width anf height of the bobbin that is frequently used in the mass produced trannies ?

Another curiousity is that the windings on transformers i have opened seem quite sloppy wound and not evenly placed and i would have thought that *even/neat* winding would have been a large factor in transformer performance ? but maybe not ?

I would likely only be able to play with flatened / rectangular or ribbon style wire anyways, as i imagine i would be constructing a rather crude jig to shape the wire and a nicely square wire would probably require something a little more sophiticated than i would build. ( ie. steel bushings for rollers pins with an adjustable gap)

thanks for the responses, robb

"Even/neat" looks nice, but only works with a few layers of fairly thick wire.

The layer of insulating enamel on the wire isn't going to survive this kind of treatment. Figure on re-enamelling the wire after you've reshaped it.

-- Bill Sloman, Nijmegen