Study Of The Influences Of Arc Nozzle Interrupting Chamber Parameters On The Breaking Performance Of SF₆ Circuit Breaker

As one of the most important electric equipments, high voltage circuit breaker is indispensable in the electric power system, so it is necessary to research the high voltage circuit breaker. The structure design of arc extinguish chamber becomes the difficult and key issue, considering the breaking characteristics influenced by the structures of chamber are important qualifications of high voltage SF₆ circuit breaker. Moreover, the influences of nozzle throat diameters on the breaking characteristics are investigated in this thesis, and a novel design method of arc extinguish chamber structures is proposed.In order to improve the large current breaking capability of high voltage SF₆ circuit breaker, the gas flowing efficiency should be improved, by increasing the operating power to increase gas pressure or improving the size and the nozzle structure of arc extinguish chamber to acquire the optimum arc flowing. For controlling the gas flowing characteristics for the high voltage SF₆ circuit breaker, the optimization design of nozzle construction is mainly researched, and the effects of the nozzle sizes on the gas flow are investigated.The moving direction of gas originating from the cylinder into the nozzle is changed from axial direction to the rotation when rotating gas slots with bevels are introduced to the upstream plain segments of nozzle. The distributions of gas pressure and velocity are directly influenced by the structures of the nozzle slots, which control the movement of the gas flow and affect the recovery strength of SF₆ dielectric during the interrupting process. Therefore, the investigation of the influences on the high voltage SF₆ circuit breaker of rotating gas slots with different angles is performed. The chamber models of high voltage SF₆ circuit breaker without rotating gas slots and with six types of different angle rotating gas slots structures are established aiming at the 126kV interrupter SF₆ circuit breaker. Moreover, the gas flow field of the above seven chamber structures are simulated and analyzed. The effect of the rotating gas slots on gas flowing is discussed by comparing the gas flow fields for different cases. Furthermore, the effects of different angle rotating gas slots structures on the distributions of pressure and velocity at various clearances are obtained by changing the angles of rotating gas slots structures during the whole interrupting process.The investigations in this thesis provide a theoretical basis to the further research on the nozzle optimum to improve the dielectric recovery strength for the circuit breakers, and have theoretical significance to optimize the arc quenching chamber.