Contact design for switching system with parallel arms - has different active areas embedded with extension for arc vapour

摘要

A contact system is designed for use in for an electrical switching unit and it consists of a pair of parallel contact arms. The contact arms are made from a base metal, whereas the contacts are made from a noble metal. The active areas of the contacts (11, 21) are different. The contact with the smaller surface area is embedded in the contact arm (2) which has an extension (10) in the direction of travel of the arc. This extension will collect evaporated contact material and extends over the contact with the larger area. The centres of the two contacts are displaced away from the direction of the arc. The thickness of the extension of the contact arm is greater than the remaining section.