Analysis and Design in Extra High Voltage Circuit Breakers Employing Shunted Capacitors

The two dimensional (2D) electric field mathematical model of arc-quenching chamber employing shunted capacitors in a 550kV dual-break extra high voltage SF6 circuit breakers (EHV SF6 CB) has been established and the influences of shunted capacitors are discussed based on finite element method (FEM). A novel structure of capacitor banks has been suggested to improve the electrical field distribution and the voltage distributions of capacitors has been analyzed based on the FEM. Finally, the lightning impulse test is performed on the CB employing shunted capacitors. It reveals that the design and construction of shunted capacitors is of vital importance, otherwise the insulation breakdown will occur between the shunted capacitors and the metal screens.