Design And Experimental Researches On The Structure And Processes Of High Voltage Interrupters

The developing history and actuality of vacuum interrupters (VI's) at home and abroad is presented in this paper first. The basic design theory and manufacture processes for VI's are summarized subsequently. Taking high voltage VI's as object, we draw some key questions needed to be solved, based on the developing level and research state existed, that educes the research contents and target of this work.Electric field optimization is a main task of high voltage VI's design. Aim at the higher level of dynamic insulation design, a whole optimized design method for high voltage vacuum interrupters is proposed. According to the vulnerable breakdown spots (weak points) theory, we adopt the multi-gaps structure of high voltage VI's, in which the maximal field is drawn into the auxiliary gaps by symmetrical potential shields. With finite element method and the optimization theory, a mathematical model of electrical field intensity in VI's was given. By the optimization of the model with finite element software, a more symmetrical electric field in vacuum interrupters was obtained and its peak value appeared in second auxiliary gap.One of the key questions in the design and manufacture processes of high voltage vacuum interrupters, is the jointing strength of ceramic to metal. Analyses were be made to find the main factors to affect the jointing strength. The solder bound contour lines of standing straight weld beads had been gotten by solved energy bound equation. So the finite element model of standing straight weld beads can be set up. By compared the stress and the pulling trials, it is concluded that the stress of standing straight weld beads is smaller than that of planar weld beads. Its overall tension and joint strength per square meter are greater than that of planar weld beads. So the standing straight weld beads should be applied in high voltage VI's with larger diameter ceramics.As the volume of a high voltage vacuum interrupter is bigger, its structure reliability becomes lower. The jointing process parameters was optimized and researched in theory and experiments. The finite element model of weld beads was set up by Surface Evolver software. Then the stress in two different cooling techniques (natural cooling and force cooling) was calculated with ANSYS code. Based the stress analysis, a better cooling technique was gotten for high voltage VI's. Its cooling time is shortened by 3 hours while the jointing stress doesn't increase and the joint strength of ceramic and metal is not decreased. The stress-rupture tests...