Current Limiters - State of the Art

Discussing the state of the art of current limitation in medium voltage range shows the limits and drawbacks of today's current limiting techniques. Focusing on up-to-date research projects in the field, the major part of this paper explains various kinds of current limitation by means of super conducting materials. The two major principles, resistive and inductive limiters, are introduced as well as hybrid approaches. Unsolved problems using high temperature superconductors HTSC for current limiting devices are discussed. Beside the HTSC projects an alternative approach, the project "NST New Switchgear Technology" at the ETH Zurich (Switzerland) is introduced. Concluding from the discussed projects, a commercial realizable fault current limiter for medium (high) voltage range based on superconducting materials is not in sight in the near future.