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 Cogging 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 Crawling in Induction Motor
As we know that Rotor Conductors of Squirrel Cage Induction Motor are skewed. It is not straight conductor as shown in figure below. Rotor conductors are skewed because of the following reasons: Primarily to prevent the Cogging Phenomenon. It is a phenomenon in which, if the rotor conductors are straight, there are chances of magnetic … Read more Why Skewed Rotor Conductors in an Induction Motor?
SFRA stands for Sweep Frequency Response Analysis. This test is very reliable for condition monitoring of physical condition of transformer winding, core and above all core & winding integrity. Why to conduct SFRA test? The winding of Transformer may be subjected to mechanical stresses during transportation, heavy short circuit faults, transient switching impulses & lightening impulses etc. … Read more SFRA Test of Transformer
The area of the window and cross-sectional area of the limb are the main dimensions of a transformer; the product of which is directly proportional to the size and weight of the Transformer. Larger this product, bigger and heavier is the Transformer. While designing a Transformer, the designer starts with an equation called the Output Equation of … Read more Why Size of Transformer Decreases as Frequency Increases?
In this post we will discuss the Magnetizing Inrush Current in a Power Transformer. Magnetizing Inrush urrent in Transformers results from any abrupt changes of the magnetizing voltage. This current in transformer may be caused by energizing an unloaded transformer, occurrence of an external fault, voltage recovery after clearing an external fault and out-of phase … Read more Transformer Inrush Current
Brushless Excitation System is a technology for providing the field current to the Synchronous Generator without using Slip Ring and Carbon Brushes. As this method of Excitation i.e. Brushless Excitation System do not use Carbon Brushes, therefore the losses because of contact resistance of carbon brushes is eliminated. Also, in case of initial start up … Read more Brushless Excitation System