This chapter deals with the transient recovery voltage (TRV) of the transformer limited fault (TLF) current interrupting condition using capacitor current injection. The current generated by a discharging capacitor is injected to the transformer, and it is interrupted at its zero point by a diode. A transformer model for the TLF condition is constructed from leakage impedance and a stray capacitance with an ideal transformer in an EMTP computation. By using the frequency response analysis (FRA) measurement, the transformer constants are evaluated in high-frequency regions. The FRA measurement graphs show that the inductance value of the test transformer gradually decreases as the frequency increases. Based on this fact, a frequency-dependent transformer model is constructed. The frequency response of the model gives good agreement with the measured values. The experimental TRV and simulation results using the frequency-dependent transformer model are described.
Experiments on Capacitive Current Interruption with Air-Break High Voltage Disconnectors