Improvement of Percussion Welding Characteristics of CuCr25 Contact Material by Decreasing Tensile Strength

Copper-Chromium contact material is widely used in vacuum interrupters. However, there are occasionally percussion welding phenomena when CuCr25 (25% weight Cr) contact material close electrical circuit, especially in the case of high rated short circuit making current tests. It was reported that the resistance welding performance of Cu Cr contact material can be improved by adding 0.1%similar to 4"/0 Te to decrease the tensile strength. In order to investigate the influence of tensile strength of contact material on percussion welding performance by adding Te (0.01%), a percussion welding experiment was designed to compare weld force between CuCr25 and CuCr25-Te contact material. The percussion welding experiment simulated the contacts in a vacuum interrupter closed a DC circuit and bounced once. The DC currents were 300A and 400A. The bounce times were 2s and 3s. With a lower tensile strength (220 similar to 240Mpa) than CuCr25 (335 similar to 345Mpa), the CuCr25-Te contact material was less proned to occur percussion weld than CuCr25 contact material. And the maximum percussion weld forces of CuCr25-Te were also lower than CuCr25 under same arcing currents and arcing times. The percussion welding characteristic of CuCr25 contact material is proved to be superior by reducing its tensile strength.