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Have a look at Prof. Sullivan's papers: https://engineering.dartmouth.edu/inductor/bytopic.shtml#arbarbPost #15 of this...
..suggests that Litz wire is best done with multiple enamelled strands, and isn't so good with just multi-stranded , non-insulated copper wire.
What are your thoughts?
I have taken a quick look at the references cited. Very briefly:What are your thoughts?
The title of the first reference should give you a clue: "Stranded Wire With Uninsulated Strands as a Low-Cost Alternative to Litz Wire"I have taken a quick look at the references cited. Very briefly:
When you have uninsulated (unvarnished) bunch of copper wires (just like a multistrand core wire), the individual strands are not in perfect contact with each other. For one, there is some air gap and second the max contact area is along a line (between two cylinders). Thus, a multi-strand wire is not the same as its effective cross section for a solid core (or a true litz bundle)- it is somewhere in between.
But why you want to do any serious business with unvarnished thin copper wires? Cost? Cutting pennies?
Copper corrodes rapidly in air and air pollution hastens it. If the wires are fine then some will break in a short time if there is some access to air. The oxide film formed on the copper surface is semiconducting but not protective enough. There is about 30% open space that is hard to fill. The wires are twisted for mechanical reasons and that adds to volume.
Litz wires can be a mess to solder (and good soldering is a key point) but I do not see any other reason - if you need it get it and use it.
My personal thoughts anyway.
The title of the first reference should give you a clue: "Stranded Wire With Uninsulated Strands as a Low-Cost Alternative to Litz Wire"
I did notice but was surprised that there were no cost-benefit analysis presented. I did look for that.The title of the first reference should give you a clue: "Stranded Wire With Uninsulated Strands as a Low-Cost Alternative to Litz Wire"
You are right; a static electric field or a static magnetic field will just ignore the enamel.Skin effect and proximity loss is all about the fields, and those fields wont even "see" the enamel.
No, but the AC fields push the current towards the outside of the wire (the skin effect) raising the effective wire resistance.Skin effect and proximity loss is all about the fields, and those fields wont even "see" the enamel.
This is not accurate. The charge carriers are pushed to the periphery by the magnetic field. Therefore if you have a given cross section of a conductor, the one with the larger periphery shall win (lower resistance).The smaller the wire, the less the effect, so LItz wire reduces the effect for larger currents by putting the current through a number of smaller wires.
No, not quite so. Please see post #3 and the reference cited therein: https://engineering.dartmouth.edu/inductor/papers/stranded.pdfThe inner conductors were simply seven 1.2mm diameter bare copper wires. Are we saying that this is just the same as a single copper strand of the same overall cross sectional area? (in terms of AC resistance)
Have a look at this: https://litzwire.com/litz_types.htmThanks, by "stranded , woven", you mean like in the following cross section picture of TEX-ELZ..?
wow thanks, it looks as if the problem is proximity effect, and these different Litzs are all about getting spacing between the individual strands.Have a look at this: https://litzwire.com/litz_types.htm
The assumption is almost wrong. All Litz wires on the market (starting with said type 1) achieve uniform current distribution in typical winding geometries, presumed the wire gauge is chosen appropriately. In special cases, e.g. inhomogenous field near air gaps, the construction type and strand length matters more....So would you agree that this is insufficient info?...they need to spec how those 60 strands are wound?
I actually believe that they just intend to have 60 strands "Junked" together willy nilly.....which means, according to our discussion, that
most of the inner strands wouldnt even conduct?
The TEX-ELZ is like type 1 in this: https://litzwire.com/litz_types.htmMy personal understanding:
The TEX-ELZ cable is simply stranded (not woven); the central core conductor stays always in the center. At sufficiently high frequency, the center conductor will drop out from conducting current.
Woven is a process (you see the outer conductor of the coaxial cables?) in which all the individual conductors are placed symmetrically. The core conductor is missing (because it is not symmetrically placed).
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