The thesis deals with the contact system of the disconnector switch with fuse SDF D02. The purpose of the work was to verify how the design of the contact system, the materials used and the contact conditions affect the voltage drop, heating and service life of the device. The research was carried out using a combination of numerical analysis in the COMSOL Multiphysics program and laboratory measurements on manufactured samples.
First, a numerical model of the disconnector switch with fuse was created and calibrated based on measurements of the reference device. Various construction and material designs of the contact system were compared with it. The numerical results showed that the K2 and K6 designs were particularly advantageous. The K2 design was only considered numerically, while the K1, K4 and K6 designs were created and verified with laboratory measurements. The most favorable experimental result was achieved by the K6 design with a double contact bridge and galvanically silver-plated contacts, in which the maximum temperature rise was 61.3 K.
The K6 design was then verified with a service life test. After 2000 switching cycles, the maximum temperature rise was 78 K, so the device still met the required criterion of 80 K. The test was continued up to 10000 cycles, after which greater wear of the contact surfaces was found, and repeated heating measurements no longer met the required criterion.
In the final part, a parametric numerical analysis of the influence of contact force, contact fit and surface roughness was performed. The results showed that contact forces between 3 N and 5 N are suitable for heating. Appropriate contact fit and quality of the contact surfaces also have a significant impact. Based on the results, the K6 design is suitable for use with a smaller number of switching cycles, while the K2 solution represents a solution for further development and experimental verification in more demanding applications.
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