Distribution Vacuum-Arc Fault-Current Limiter. Final Report

摘要

The objective of this project was the demonstration of the feasibility of using a vacuum arc as the basis for a distribution class fault current limiter. The concept used was an electric discharge in vacuum between a hollow cylindrical anode and a short rod cathode located on the axis of the anode. The device has two modes of operation. One mode utilizes an externally applied axial magnetic field; the other uses the discharge's inherent magnetic field. A series of experiments yielded analytic models of the two modes of operation. It was found that for both cases, high arc voltages were generated by the conduction of current through an electron space charge region (sheath) near the anode. It was concluded that the vacuum arc with applied axial magnetic field was the most suitable mode for use as a commutating switch for a switched resistor fault current limiter. The test device used for the project could reliably commutate currents of 6.4 kA peak. The design of a 20 kA peak prototype commutating switch was completed but the prototype was not constructed. This vacuum arc device with applied axial magnetic field may be considered an alternative switching device for dc applications. (ERA citation 07:043293)