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Title: Design of Electrical Contacts for Fast Mechanical Disconnect Switches
Committee:
Dr. Lukas Graber, ECE, Chair , Advisor
Dr. Maryam Saeedifard, ECE
Dr. Michael Varenberg, ME
Dr. Santiago Grijalva, ECE
Dr. Michael Steurer, Florida State
Abstract: The objective of this research is to develop an understanding for the design considerations for electrical contacts with the goal to improve the performance of fast mechanical disconnect switches (FMS). The design of electrical contacts involves tradeoffs between current rating, voltage rating and speed of FMS, which are demonstrated for an FMS protype based on piezoelectric actuators. The research focus involves the selection of optimal geometries (profile) for the contacts and selection of the most suitable contact material to achieve certain performance goals Contacts with uniform field geometries such as Bruce and Rogowski were shown to minimize the enhancement of the electric field when open and contact resistance when closed. The most suitable contact materials are identified by deriving the material indices that affect performance of FMS. The material selection process identified minimizing power loss, fretting wear and overheating as the major objectives and copper based contact materials as the most suitable for this application. The impact of fretting wear was further studied and was found to result in a derating of voltage and current rating of FMS. The potential performance gains with dissimilar contact materials are explored. Dissimilar contact materials were found to improve the life expectancy of FMS by delaying the increase in contact resistance caused by fretting wear. The use dissimilar contact materials to redirect heat away from the temperature sensitive components via thermal rectification is demonstrated through simulation and experiments. The combination of these two effects allow for the design of electrical contacts that can significantly improve the performance of FMS.
