Development of Contact Material Solutions for Low-Voltage Circuit Breaker Applications (2)

The focus of the experimental studies was in the influence of contact material composition, production parameters and the contact material - breaker interaction, as the performance of the breaker is a function of breaker design, contact material and especially their interaction. Therefore, typical material combinations used for low voltage protection devices were compared by means of their switching behavior and performance. Model-switch tests have been carried out to show this performance under stable and well defined boundary conditions. The chosen test parameters simulate device tests, excluding the influence of switching device kinematics and tolerances. Focus of the tests was to scrutinize the influence of the material composition on the erosion behavior and contact resistance for AgWC materials. Additionally a comparison on the performance of different silver refractory metals like AgW or AgMo at comparable vol.-% refractory metal was made. Furthermore, the impact of different graphite contents, manufacturing parameters and fiber orientation of AgC materials on weld break forces have been worked out. This experimental quantification of influences can be seen as a basis for contact material selection during protection device design.