
Thermal Effects 8-11
the impregnation process. If the equivalent thermal conductivity k
cu,ir
is
k
nown,
t
he
t
hermal
r
esistance
b
etween
t
he
w
inding
a
nd
t
he
s
tator
l
ami-
nations
c
an
b
e
c
omputed
u
sing
t
he
e
quation
r
eported
i
n
p
revious
s
ection.
W
hen
t
he
s
lot
ll
f
actor
k
f
, the slot area A
slot
[cm
2
], and axial core length
L
core
[cm] are known, the following relation can be used as a reasonable
s
tarting value:
k k A L
cu,ir f slot core
( )= −
−
0 2749 1
0 4471
.
.
(
8.14)
e
q
uantity
i
nside
t
he
s
quare
b
racket
r
epresents
t
he
a
vailable
n
et
v
olume
i
nside
t
he
s
lot
f
or
t
he
w
ire/slot
i
nsulation
a
nd
t
he
i
mpregnation.
R
easonable values to be used are in the ra ...