Re: Litz wire

To: tesla-at-pupman-dot-com
Subject: Re: Litz wire
From: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 04 Dec 1999 14:22:41 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Brian wrote:

> I think litz wires were one of Nikola Tesla's inventions.  Either that or
> he just used them a lot.  They also have decreased inductance because
> each wire is like a inductor and when you put them in parallel 1/N*L.  N
> is the number of wires and L is the inductance of a single wire of the
> strand.  Unless because it is twisted this increases inductance, but I
> don't know if this is significant or not.  Decreased inductance decreases
> AC resistance or reactance.

Litz wire has the same inductance of solid wire. The increase in 
resistance due to skin effect is also about the same. The difference 
is in losses due to eddy currents induced in the wire by the changing
magnetic field crossing the coil winding. Essentially the same reason
why the iron cores of transformers are laminated, and the same reason
why ferrite cores are composed by many insulated islands of 
ferromagnetic materials, that are conductive. I don't know who
invented it. Probably someone called "Litz".

Antonio Carlos M. de Queiroz