What is Litz Wire?
The term "Litz wire" is derived from
the German word "litzendraht" meaning woven wire. It is contructed of
individually insulated magnet wires either twisted or braided into a uniform
pattern.
Litz wire sizes are often expressed in abbreviated format as
follows:
N / XX, where N = the number of strands and XX = the AWG (American
Wire Gauge) size of each strand. For example a typical size of litz wire might
be expressed as:
"20/30" or 20 strands of 30 AWG. After the size follows the
insulation and serving/jacketing options as will be described below.
Insulations:
Here we are describing the type of
insulating enamel on each strand of magnet wire. The most common insulations for
litz are *Single* & *Heavy* build Polyurethane-Nylon meeting the NEMA MW
80-C industry standard for magnet wire. Other insulations types & builds are
possible so please inquire. You can find additional information on the various
enamels available on our web site under "Magnet Wire - General Info."
Twisting Tightness:
The standard twist configuration is
12 twists per foot (TPF) on most litz wires however non-std twisting is
available on request. Sometimes the twisting is expressed as twist per inch
(TPI). The maximum # of twists in a given length is limited by the size of the
strands. Generally speaking, even in the smallest wire diameters, the highest
TPF possible is 300 - 360 TPF.
Served vs Unserved:
Litz wire may be quoted as "SERVED"
& "UNSERVED". SERVED simply means that the entire litz construction is
wrapped with a nylon textile or yarn for added strength and protection. Another
option is to have the litz construction jacketed with FEP *TEFLON (tm) or PVC
instead of the nylon serving. Typical teflon thickness is .005" wall up to
.015". *TEFLON is a tradename of Dupont Corp.
Why Use Litz Wire?
Litz construction is designed to
minimize the power losses exhibited in solid conductors due to "skin effect".
Skin Effect is the tendency of radio frequency current to be concentrated at the
surface of the conductor. Litz constructions counteract this effect by
increasing the amount of surface area without significantly increasing the size
of the conductor. Generally speaking, constructions composed of many strands of
finer wires are best for the higher frequency applications. Polyurethane-Nylon
is the film most often used for insulating individual strands because of its
solderability. However, you may feel free to inquire about other higher
temperature insulations as well.
Frequency vs. AWG Strand Size
All
Values in KHz
1 To 10.0 - 30 AWG
10 To 50.0 - 33 AWG
50 To
100.0 - 36 AWG
100 To 200.0 - 38 AWG
200 To 400.0 - 40
AWG
400 To 800.0 - 42 AWG
800 To 1600 - 44 AWG
1600 To 3200
- 46 AWG
3200 To 5000 - 48 AWG
