A new range of vacuum interrupters developed using latest modeling tools

Vacuum interrupters have been widely used for power distribution systems since the 1960s and hare proven their reliability in service. Work is continuing to improve this technology and to satisfy the growing requirements of the electrical power industry. A new family of vacuum interrupters, the so called VG range, has been developed covering power The key drivers for this project were an optimised design, reduced development time and expenditure and reduced environmental impact. To achieve these targets a maximum of modeling techniques was employed. Vacuum interrupters have many electrical functions such as interrupting short circuit currents, conducting the rated current and withstanding lightning impulse voltage. Furthermore, they also have to fulfill important mechanical duties. The heart of each vacuum interrupter is the are control geometry that is required to distribute the arc energy equally over the contact surface. In the course of the development three dimensional electro-magnetic modeling was applied to optimise the ohmic resistance of the interrupters and to extend the short circuit interruption performance up to 63 kArms. Electrostatic calculations were also used. Relevant areas were not only the dielectric design of the interrupters itself, but also the interrupter mounted in circuit breakers or the optimisation of the interrupter manufacturing process. Finite element calculations were used to optimise the mechanical performance by simulating and varying different geometries and taking into account a variety of materials and their properties. The paper presents the modeling approach taken for this development project by discussing some actual examples.