Research Of The Breaking Overvoltage Of High-voltage Current-Limiting Fuse

High-voltage current-limiting fuse is a very common protector which is used to protect generator,transformer and other important equipment. Current-limiting fuse can cut off the short circuit current rapidly, but it will produce an overvoltage acting on the facility at the mean time. We can use the combined arrester and fuse to limit the overvoltage. The paper mainly discussed the overvoltage at the different situation during the fusing process. It provided rules for designing arrester; it also gave help for fuse design.The fusing process of the fuse is a very complex thermoelectric coupling course. We built a current field model of the fuse based on the current continuity equation. The model is correlative with temperature. Temperature field model is also built based on temperature field differential equation. We have done some assumptions and simplifications to combinate the two equations with the conservation of energy to set up a thermoelectric coupling model describing the fusing process. To solve the equations the finite element method is adopted based on ANSYS. The paper discussed two fuse wires with different shape and introduced detailedly how to built the fuse model, how to confirm boundary conditions,how to load and how to solve. Compared the calculated curve and the real assay curve we can make a conclusion that: this method can calculate the melting time of the fuse at the huge short current (more than 50 times of the current rating) with the error less than 5%; the resistor and time characteristic can also be acquired, it provided the date for overvoltage calculation of the fuse model.The research of the overvoltage during fusing process is based on short circuit test of the fuse. We built the simulation model of the short circuit test using EMTP/ATP. In this model the fuse is simulated by a time variable nonlinear resistor combined with a switch, the nonlinear resistor represented the fore-arc resistor during fusing process, the switch is used to control the cut off time, and both of the above is calculated by the ANSYS. Compared the real assay curve and the simulation wave we found that: the calculated overvoltage amplitude value is accuracy with error less than 5%.But the wave is more or less different especially the part of the post-arc. At last the paper discussed the source of the error and developed a new method to deal with the fuse model. We used several nonlinear resistors in series to replace one single nonlinear resistor. With this method we built a more accuracy fuse model. Using this model we can obtain a more similar simulation result compared with the real overvoltage.