Reduction of inrush current by demagnetization of magnetic core

The peak value of three-phase transformer's inrush current depends, among other factors, on value of the residual flux in the iron core. Higher residual flux produces the inrush current of greater value. Diminishing of magnetism in the core can reduce value of the current. This article presents demagnetization of the transformer as a method of inrush current reduction. In the method proposed a condenser is the source of energy for demagnetization. Different condenser capacitances and voltages are implemented for calculation test to determine optimal values of these parameters. Later the residual flux established after demagnetization of the core is calculated for several initial values. Influence of the flux new value upon the inrush current is discussed.