Direct-on-Line or DOL Starting of Induction Motor

Direct-on-Line or DOL Starting is the simplest mode of starting of Induction Motor where the stator is directly connected to the mains supply as shown in figure below.   The motor starts with its own characteristics. When it is switched on, the motor behaves like a transformer with its secondary, formed by the very low … Read more

Why does Induction Motor has Poor Power Factor at No Load

Induction Motor when started at no load has very poor power factor in the range of 0.1 to 0.3. For understanding the effect of loading on the power factor of Induction Motor, we will consider three components of current flowing in an Induction Motor namely Magnetizing Current, Stator Loss Component of Current and Load Component … Read more

Why Rotor Core Loss is Negligible for Induction Motor?

We have already discussed about losses in electrical machine in “Losses in Electrical Machine – Core Loss”. Under normal operating condition, the core loss in the Rotor of an Induction Motor is negligible. In this post we will discuss about this.     Core loss consists of Hysteresis Loss and Eddy Current Loss. Hysteresis Loss … Read more

Cogging in Induction Motor

Cogging phenomenon is observed in Squirrel Cage Induction Motor during starting for certain combination of Stator and Rotor Slots. In Cogging motor fails to start at all. For better understanding a view of Stator Core Laminations, Stator Core and Rotor of Squirrel Cage Induction Motor is shown in figure below. Squirrel Cage Induction Motor Stator … Read more

Crawling in Induction Motor

Crawling is a phenomenon in which Induction Motor operates at very low speed. Crawling is caused by the presence of space harmonics in the air gap flux. For understanding Crawling, there are some points which are very important to know. Those points are as follows: Speed of Rotating magnetic flux = 2f/P, where f is … Read more