Building of short circuit ampere - second characteristics for a series of amorphous core transformers

Abstract

In this paper, the finite element method (FEM) with Ansys Maxwell software is used to simulate a series of ten amorphous core transformers (AMCT) power. These AMCT operate in the three-phase short-circuit fault mode on the low voltage winding. The study determines the maximum short-circuit current on the low voltage (LV) and high voltage (HV) winding; of 10 different AMCT power. From this result, the study builds the short-circuit ampere-second characteristic of AMCT. Thanks to that, the transformer operator determines the correct short-circuit cutting time to support the selection of the right fuse cut out (FCO). Thereby, the AMCT will avoid the harmful effects of electromagnetic force that causes the AMCT winding to break. This research result helps us to determine the correct short-circuit cutting time of the FCO to disconnect the transformer's electrical connection from the high-voltage grid. From there, we protect against short-circuit breaking and displacement of the winding caused by short-circuit electromagnetic force.