
Induction Motor 4-11
function of the slip is as a power splitter of the transmitted power, P
T
, between the rotor joule losses, P
jr
,
a
nd the converted mechanical power, P
mech
.
4.2.1 Starting Torque and Current
Imposing in the torque relation a slip equal to one, the starting torque value can be obtained as
T
p
V
R
R R X X
start
s
eq
r
eq r eq lr
=
+ + +
3
2
2 2
ω
( ) ( )
(
4.33)
In the same way, the starting current can be determined by
I
V
R R X X
start
eq
eq r eq lr
=
+ + +( ) ( )
2 2
(4.34)
e denominator of the previous relation is the short circuit impedance, oen dened as locked rotor
impedance. It is evident that the starting current corresponds to the locked