Electrical contacts are widely used for telecommunication and electric power systems as a device mechanically making and breaking electrical current. In the future, they will be more indispensable. In this paper, we explored the possibilities of early lifetime prediction of Ag-Ni contacts for an electromagnetic contactor. Contact erosion often leads to the contact failure and the system fault. Especially, for heavy electrical systems, the failure can cause critical troubles. We must estimate approximate periods of the system fault to avoid the troubles. The tests of lifetime are very important for that purpose. However, the tests often require enormous amount of time. We investigate the possibilities of lifetime prediction of contacts. In the past work, we confirmed that the mass loss could lead to the contact failure of Ag-Ni contacts and the mass loss of cathode was in proportion to total arc energy generated between the anode and the cathode. At this time we measured the mass losses of cathodes with a few making and breaking operations for more samples, and accurately predicted the mass losses after a lot of operations. We compared them with experimented results of a lot of operations.
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