High voltage current limiting device

Abstract

A high voltage, current limiting device is connected in series with a high voltage power source and a protected load to interrupt current for an over-current condition [Typically 50 kA]. The current limiting device includes a current sensor/isolator and a switch connected in series. A current limiter, which may include a fuse or polymer current limiting material, is connected in parallel to the current sensor/isolator. The current sensor/isolator includes a pair of electrically insulated supports secured to a plurality of support rods to maintain the insulated supports at a predetermined fixed spacing to support an expulsion fuse. The expulsion fuse link includes a pair of copper conductors of adequate current carrying capability that are attached to ends of a main weak link fuse. A pair of coil springs hold the weak link fuse under tension to repel the conductors apart when the weak link fuse melts open during an over-current condition. An electrically insulating flapper pivotally connected at one end of a support rod provides a barrier between the source side and the load side of the current sensor/isolator when the main weak fuse melts open. One embodiment of the current limiter may include a high voltage polymer current limiting (PCL) device having a conductor-filled polymer composite material disposed between a pair of electrodes. The electrodes are forced inwardly by a pair of opposing springs to compress the composite material. The composite material, electrodes and springs are surrounded by pure silica, e.g., sand, within an enclosure.

Dependencies are inferred from the claim text.