Analyses Of Hydraulic Operating Mechanism Characteristics For High Voltage SF₆Circuit Breaker

As the power source of the circuit breaker, the operating mechanism drives the arcextinguishing system directly or through the linkage, and its motion characteristics play animportant role in the opening and closing performances and the capability of the circuitbreaker. The hydraulic operating mechanism, as one of the branches, usually operates withthe SF6circuit breaker. So, it is important for improving the overall level of the circuitbreaker, to research the hydraulic operating mechanism, establish the simulation model toanalyze its motion characteristic. Main research covers as follows:According to the structure features and the operating principal of the level3valvesystem, the forces on the first to the third level valve are analyzed, using the theory ofHydrodynamics and Electromagnetism, to calculate the moving time of the whole valvesystem during the opening process of the circuit breaker. Based on the dynamicsfundamental laws and the first law of thermodynamics, the unified mathematical model ofthe hydraulic operating mechanism, the arc-quenching chamber and the linkage isdeveloped. The model of the accumulator outlet pressure is also considered. Consulting theBernoulli equation and its structure features, the throttling characteristics of the cushioningdevice are analyzed and the mathematical model is given out. According to themathematical models, the co-simulation model of the hydraulic operating mechanism andthe arc-quenching chamber is established.Moreover, the hydraulic operating mechanism of550kV high voltage circuit breakeris taken into consideration, the key structure parameters, such as the inner diameter of thehydraulic cylinder, the outer diameter of the piston rod, the piston stroke of the hydrauliccylinder, and the pipe diameter, are analyzed, to find the main influence fctors on theopening performance of the hydraulic operating mechanism. Based on the research above,the combination simulation of the hydraulic operating mechanism and the arc-quenchingchamber of252kV high voltage circuit breaker has been realized, and the above influence factor on the opening capability has been analyzed.