Study of Induction motor characteristics and calculating starting time and operational stability

1. Similarities between mechanical Clutch and Induction motor.

Clutch operation

Consider driving shat of a mechanical clutch with Torque T and speed w1 and the driven shaft has Torque T and speed w2.

If we consider there are no losses then torque of driving shaft is same as torque is driven shaft.

The relationship between the angular velocities of the two shafts are give by the equation

w1 = w2(1-s), where s is the slip value

Indcution motor

In an induction motor the motor speed wm is always less than the synchronous speed ws (the speed of stator\'s rotating magnetic field)

The relationship between motor speed and synchronous speed is given by the equation

wm = ws(1-s), where s is the slip value

It can be clearly seen that these two equations are similar in nature. Thus the operation of an induction motor is similar to a mechnical clutch

2. Calculating the starting time of an indcution motor drive with following parameters:

J=10 kg-m²,

T = 15 + 0.5wm

T_l=5+0.6ω_m

3. A drive has following equations for motor and load torques:

Tm=(1+2ω_m)

T_{l= 3} √ω_m

Obtain the equillibrium points and determine the stability