Anisotropic high temperature superconductors as variable resistors and switches

Several anisotropic high temperature superconductors show critical current densities which are strongly dependent on the direction of an applied external magnetic field. The resistance of a sample can change by several orders of magnitude by applying a magnetic field. The potential for using the field dependent variable resistor or switch for applications in power systems is evaluated. Test results with small samples are presented, The requirements for large scale applications are outlined. The magnetic field triggering requirement, the frequency response of the device, use in 60 Hz AC circuits and heat transfer considerations are investigated. Several application examples are discussed. Use of the variable resistor as a fault current limiter, as a switching element in rectifier circuitry and as an improved dump resistor for a superconducting magnet is presented.<
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