Effects of transformer inrush current

Inrush current in transformers is often gets less importance compared to other effects/faults. Though the magnitude of inrush current may be in some cases less than compared to short circuit current, the frequency and duration of inrush current is generally more frequent, hence it will likely have more adverse effect compared to other faults. Inrush current may flow when transformer is energised. The amount of inrush current depends on when in the voltage cycle the transformer is energised and residual flux in the transformer. The other type of inrush current is sympathetic inrush current which flows in already energised transformer when another transformer is energised in parallel connected line. \n \nThis report contains basic principle, fundamental theory and relevant laws of the transformer and inrush current. A number of factors affecting inrush current are discussed. The inrush current theory and their equation are derived. The effects of inrush current are described in brief. As a part of this project a number of effects and factor affecting inrush current are considered for simulation. The Matlab Sim-Power system is used for the simulation. The simulation results compared with each other and also data available from actual same size transformer. Finally six solutions to inrush current mitigation techniques with a practical low cost answer are provided.