Failure Analysis of High-Voltage Circuit Breakers Servicing in 500 kV HVDC Converter Stations

The circuit breakers for AC filters (ACF) are key power equipment that is used for energization and de-energization of ACF. The objective of this paper is to survey typical failures of SF6 circuit breakers used for ACF in operation. All of the failures presented in this paper are analyzed through methods like waveform monitoring, simulation, and ingredient testing after disassembling. There are 297 failures mentioned in this paper, which can be classified into three main types-failures triggered by restriking, flashover of insulating components, and mechanical failures, which account for 45%, 24%, and 31 %, respectively. Among them, restriking usually happens due to the breakdown of the key components like nozzle and contacts, or the particles adhered to the surface of arc-extinguishing chamber. Flashover is usually derived from an insufficient design of the components or the particles cluttering on the surface of the insulating components. While mechanical failures usually includes the leakage of SF6 gases and the break of mechanical transmission components.