Interdependency of test environment and current breaking capacity of a model vacuum switch

Abstract

In contact material development it is elementary to have a fundamental understanding of the effects of the test environment on the switching performance. However, the complexity of those dependencies make it difficult to identify a definite cause-effect relationship between contact material and switching properties, especially if the effect of small variations in the contact material, such as the particle distribution and the morphology, shall be investigated. This paper sensitizes to the strong interdependencies of test conditions and current breaking capacity. To identify these dependencies the test environment was systematically modified. The modifications could reproducibly be correlated with their effect on the test results. In particular, the topology of the high current circuit and the contact bolt design showed strong effects. The circuit topology was optimized for reduction of the magnetic flux density within the contact gap, and it was standardized to ensure long-term reproducibility of future results. The modifications of the test circuit could also be recognized in the characteristic arcing voltage.