Erosion dependency of 3-phase contactor contacts on configurationof loads

摘要

Following the concept of symmetrical components and trigonometry,derived expressions for the voltage across nonarcing open contacts ofthree phase contactors used with various load configurations arediscussed. The validity of the derived relations is examinedexperimentally. A phase current of 20 A at a line to line voltage of 415V and a gap-length of 2 mm on Ag-SnO₂ contacts are used for5000 operations with loads arranged in delta and star configurations. Aninspection of SEM photographs demonstrates the dependency of erosionupon load configurations