The Design Of 126kV 31.5kA Self-energy SF6 Circuit Breaker

It is a very high advancement to the development from two-pressure arc-quenching chamber and single-pressure arc-quenching chamber to the self-energy arc-quenching chamber now for arc-quenching theory of SF6 CB make use of the arc blocking effect, namely arc-self-energy, to increase SF6 gas pressure in the arc-quenching chamber and get the efficient blasting effect to extinguish the arc when the arc current is zero. So the operation machine only provides kinetic energy needed for contactor moving, then operation power is decreased largely and machine is simplified. Consequently the structure and size of arc-quenching chamber are decreased and reliability of CB is improved greatly. So the development of self-energy SF6 CB is very important.In the paper, the math model of arc-quenching chamber air-pressure character is built on the base of 126kV/31.5kA self-energy SF6 CB's exploiting, then the theory analysis and calculation is deeply been done for cylinder radius, nozzle spout radius and opening position of moved contact that they have the essential effect for the use of arc energy in the course of opening. Arc-quenching chamber parameter is confirmed according to the request of full opening and fault opening when the CB is opening. In addition, electric field distribution of arc-quenching chamber is calculated in adopting ANASYS software and the largest electric field intention is analyzed under the impulsion voltage and infrequency voltage, then the size of insulation porcelain cover is determined. Designed product reaches miniaturization request.The small operation power, few component parts, appropriate structure, low noise and high reliability spring operation machine is designed for self-energy CB. Choice and comparison of structure are done and the choosing spring, fatigue intension, opening coil and so on are studied in design.Through the research and design from the above, 126kV/31.5kA self-energy SF6 CB's sample is manufactured in the paper. According to GB, type test is done and the analysis instruction of CB's opening test is done. The test result indicates that 126kV/31.5kA self-energy SF6 CB has excellent opening character and also proves the reasonability of arc-quenching chamber structure design.