Calculation of very fast transient over-voltage in transformer windings

Finite-difference time-domain (FDTD) method is introduced to calculate the transient over-voltage of transformer windings using multi-conductor transmission lines (MTL) model. The termination of windings is characterized by VFTO, which is caused by disconnector switching off short bus. Discrete formulation of transformer windings in the time domain is given. Several representative curves with respect to time in transformer windings are illustrated. The maximums of over-voltage and electric field intensity generated in wire coils and in wire turns are also given. It is essential for transformer´s insulation design.