3-phase induction motor formulas pdf
- how torque is produced in induction motor
- how is torque generated in an induction motor
- how the starting torque is produced in a single phase induction motor
- how is torque generated in electric motor
Torque of induction motor formula.
Starting Torque Equation of Induction Motor
Full load torque equation of induction motor is as follows:
The starting torque of a motor is that torque which is produce by it at start.
Starting torque of single phase induction motor
It is denoted by Tst and corresponds to s = 1. So by substituting s = 1 in above expression, we get the expression for starting torque. Therefore starting torque formula for induction motor is as follows:
Maximum Torque at Start
The condition for maximum torque is
s = R2/X2 or R2 = sX2,
R2 = X2 (since at start s = 1)
Thus to obtain maximum torque at the start, the value of rotor resistance must be equal to the rotor reactance at standstill.
However, the normal rotor resistance is quite small as compared to the reactance, otherwise, the rotor losses will be high and the efficiency of the motor will be low.
Hence to obtain maximum (higher) at the start some external resistance is added in the rotor circuit which is only possible in the case of slip ring induction motors.
Once motor picks up speed this external resist
- how torque is produced
- how does an induction motor develop torque