Voltage transformer(TV) interturn short circuit at generator outlet will cause unbalanced voltage in system

resulting in zero sequence stator ground fault protection of generator fundamental. The external characteristics of TV fault are of great significance to stable operation of the unit. In order to understand the external characteristics of TV fault

based on Maxwell and Simplorer software

a field circuit direct coupling finite element model for the electromagnetic conversion process of single-phase voltage transformer is established

which can realize data exchange between field circuits at each calculation step. In view of the large number of turns of TV primary winding

which is difficult to model directly

winding grouping technology is proposed. An experimental platform is designed and built to verify the accuracy of the simulation model. Based on the calculation results of finite element eigenvalues

the electrical and magnetic eigenvalues of TV in different operating states are analyzed

and the analytical model of TV inter turn fault based on winding grouping technology is further given. The simulation results show that

the TV turn-to-turn fault model is accurate and effective in analyzing the primary current

circulating current and other fault characteristic quantities.