ATP/EMTP Study of Ferroresonance Involving HV Inductive VT and Circuit Breaker Capacitance

Ferroresonance is a phenomenon usually initiated by transients in power networks resulting from, for example, switching operations or ground faults. Non linear behavior of the core of an inductive voltage transformer results in magnetic saturation. Long-lasting ferroresonant states are dangerous to equipment due to prolonged overvoltage and large overcurrents in HV windings. In the present article, numerical simulations of the ferroresonance phenomenon in a HV inductive VT are presented. The ferroresonant oscillations analysed result from interaction between the voltage transformer and the grading capacitance of a circuit breaker.