Evaluation of AgSnO2 material on high current DC switching

An experimental study was conducted to evaluate the performance of AgSnO/sub 2/ contacts (with 12 wt.% and 15 wt.% of SnO/sub 2/) for high-current DC switching. The contacts were tested in a solenoid-operated fixture equipped with an arc quenching chamber and an in-line magnetic blow-out system. The switching experiment was performed at 480 V DC with currents up to 1500 A. The duty cycle was two operations per minute. Metallurgical analysis of the contact surface and cross section were performed after the tests. A qualitative comparison of the test results to AgWC and AgCdO was made. The Ag-(15 wt.%)SnO/sub 2/ contacts showed better weld resistance than AgCdO and better contact resistance than the AgWC. The Ag-(15 wt.%)SnO/sub 2/ was proved to be a promising candidate for high-current DC switching application. The reduced closing contact bounce significantly improved the contact welding and contact erosion characteristics and greatly relaxed the requirements on contact materials.<
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