Should transformer to be protected against inrush current?
We all know that when transformer is energized at no-load condition, core will get saturated. Due to that, huge inrush current is demanded from the source voltage. This phenomenon is quite frequent in all the types of machines. In rotating machine, there are several methods like direct on line(DOL), soft starter etc used to reduce the inrush current as it effects the dynamic performance of the rotor during starting period. Transformer also has the inrush effect but it is not given any consideration yet. There are certain parameters which put light on the importance of studying this phenomenon in stationary machine. Inrush current condition in transformer is transient phenomenon. So, it mainly understood by two parameters namely magnitude and duration. Magnitude of inrush current depends on : - Switching angle of source voltage - Rating of transformer - Impedance of energizing system - location of windings (inner or outer) - Magnetic properties and residual flux