Electrical contact characteristics of YBaCuO bulk

A persistent current switch (PCS) is used for superconducting applications, such as superconducting magnetic energy storage (SMES) system. The authors have proposed a mechanical switch of Y-Ba-Cu-O (YBCO) bulk as a mechanical PCS. In previous study, in order to investigate the contact characteristics of switch, 50 A current test was performed and the contact resistance between two contacts was measured by four-terminal method. As a result, it became clear that polishing and metal depositing on contact surfaces was effective methods to reduce the residual resistance. This paper focused on the greater current test (above 50 A) in order to perform more practical experiment as PCS used for SMES. In this experiment, the authors examined the characteristics to the transfer current of switch, which was not obtained by former 50 A current test. As a result, it was obtained that the transfer current had a relationship with the layer thickness of deposited Ag on contact surfaces.