Li Yang

This paper presents the numerical study of current self-excited oscillations during the opening of HVDC metallic return transfer breaker (MRTB). The switching arc is simulated using magneto-hydrodynamics (MHD) theory coupled with the electric circuit variation. The calculated result gives good agreement with the experiment, and shows that the arc model can accurately simulate the current oscillation and the commutation process in MRTB. The MRTB prototype in this study is designed to break about 5.2 kA of DC current. The results from both simulation and experiment show that the current oscillation starts at about 16.5 ms and the total arc time is about 24 ms when the commutation capacitor bank and inductor are 72 μF and 173 μH, respectively. This study can help improve the current interruption capability of MRTB.