High Current Making Switch

A fast making (closing) switch for high currents is described. It was built to test a homopolar generator developed at the University of Texas. The switch is laid out to carry 300 kA for 3 seconds. It is pneumatically operated and can be tripped without transferring any valves; consequently timing is precise and fast. The contacts are designed to avoid arcings and for minimal inductance. Contact pressure is enhanced by the electromagnetic forces of the current. Tests on the prototype were carried to 550 kA. Oscillograms of the tests are shown. This prototype confirmed the validity of the design criteria and forms the basis for future designs.