Analysis of Equivalent Circuit
The total power transferred across the air gap (Pg) from the stator is
 |
(17) |
Hence, the rotor Ohmic loses and the internal mechanical power are given as
 |
(18) |
(19) |
The internal (gross or air gap or the electromagnetic torque) torque developed per phase is given by
 |
(20) |
(21) |
Thevenin's Equivalent Circuit of Induction Motor
When the torque-slip or power-slip characteristics are required, application of Thevenin's theorem to the induction motor equivalent circuit reduces the computation complexity. For applying Thevenin's theorem to the equivalent circuit shown in Figure 8 , two points a , b are considered as shown in Figure 9 . From these points the voltage source V1 is viewed and the equivalent voltage at point a and b is
 |
(22) |