Study of the switching arc characteristics of a 500 kV HVDC self-excited oscillatory metallic return transfer breaker

Studies of circuit breakers are of interest to high voltage direct current (HVDC) power system. The method for investigation of the switching arc characteristics of a 500 kV metallic return transfer breaker (MRTB) is presented in this paper, by coupling magneto-hydro-dynamics (MHD) arc model with the resonant circuit equations. 2-D MHD arc model taking account of important physical processes of mass flow, Ohmic heating, radiation energy transfer, momentum exchange, Lorentz force and current flow is developed, and then the influence of stray resistor is analyzed under the interrupting current of DC 4 kA. Calculation results of the distribution of temperature and gas pressure in the nozzle region are presented, where the shock wave and negative voltage-current characteristic of arc are discussed. The calculated arc current and voltage are in agreement with the experimental results to some extent, which could verify the validity of the calculation method partially.