Litz
Wire
For
optimum
performance,
the
Litz
constructions
covered
in
this
section
are
made
with
individually
insulated
strands.
Common
magnet
wire
film
insulations
such
as:
polyvinylformal,
polyurethane,
polyurethane/nylon;
solderable
polyester,
solderable
polyester/nylon,
polyester/polyamide-imide,
and
polyimide
are
normally
used.
The
outer
insulation
and
the
insulation
on
the
From
Table
1
and
other
empirical
data
the
following
table
component conductors, in
some
styles,
maybe
servings
of
recommended
wire
gauges
vs. frequency
for
most
Litz
or braids of nylon,
cotton,
Nomex1, fiberglass or
ceramic.
constructions has
been
prepared.
Polyester,
heat
sealed
polyester,
polyimide
and
PTFE
tape
wraps
along
with
extrusions
of most
thermoplastics
are
also
available
as
outer
insulation
if
the
applications
dictate
special
requirements
for
voltage
breakdown
Table 2
or
environmental
protection.
Litz
Design
Typically,
the
design engineer
requiring
the
use of
Litz
knows
the
operating
frequency
and
RMS
current required
for
the
application.
Since
the
primary
benefit
of a Litz
conductor
is
the
reduction
of
A.C.
losses,
the
first
consideration
in
any
Litz
design
is
the
operating
frequency.
The
operating
frequency
not
only influences
the
actual
Litz
construction,
but
is
also
used
to
determine
the
individual
wire
gauge.
Ratios
of
alternating-current
resistance
to
direct-current
resistance
for an
isolated
solid
round
wire
(H)
in
terms
of a
value
(X)
are
shown
in
Table
1.
After
the
individual
wire
gauge
has
been
determined
and
assuming
that
the
Litz
construction
has
been
designed
such
that
each
strand
tends
to occupy
all
possible
Table 1
positions
in
the
cable to approximately
the
same
extent,
the
ratio
of
A.C.
to
D.C.
resistance of an
isolated
Litz
conductor
can
be
determined
from
the
following
formula.
The
value of X
for
copper
wire
is determined by
Formula
1.
1
DuPont
Registered
Trademark
2
See
Radio
Engineers
Handbook
-
Terman,
pp.
30-83.
130
