It is important for an induction motor to perform as per the aids and expectations of the industrial needs. Thus, any industry scan the following factors that helps in better performance of the motors:
Resistance maintained by rotor:
It is important to determine the rotor performance which is generally examined by the material used in the construction of the same. Since rotor resistance is the most significant parameter, it is also examined in squirrel case induction motor by the area of cross-section at the end of the rings. Please note that the most common material used in the rotor resistance copper and aluminum.
The performance of the rotor is generally affected by the fluctuation in rotor resistant. How, if you ask? Let’s discuss few points under the favor of statement.
While you start the induction motor, the increase in starting resistance results into increasing value of starting torque. The torque diminishes as soon as it reaches its maximum value.
The rotor resistance is inverselypropositional to starting current and operative efficiency. Also, the increase in rotor resistance results into percent regulation without affecting the maximum torque as it depends upon reactance of the rotor itself.
Shapes of both stator and rotor slots and steep
Though it is said that slots in the rotor shall be parallel to the shafts, but the twist is attained by given flight or skew. In order to reduce the noise and vibration of the motor including caging and synchrous cups with the procedure of skewing the stator or rotor slots.
The shapes of rotor steeps and slots plays an important role in the induction motors as it affects the reactors. The effect of reactance is then followed by starting current and maximum torque affected at the same level. In other words, we can mention that under the presence of deeper slots the induction motors results into leakage reactance. The procedure is followed by much lesser value of maximum torque and slip along with starting current under the consideration to maximum torque.
It is important to reduce the harmonic torques for a better performance of induction motors. Mentioned below are some methods to reduce the same:
If air gap length can be increase
If rotor slots can skewed
If winding is possible in integral slots
Air gap length
In order to operate at low power factor the induction motors consider air gap as one of the two main sources.
If air gap length is reduced over the expected limit, it can cause the following situations:
Overload capacity will be reduced
From magnetic pull to noise and pulsation losses will realize a much higher increase