Patent ID: 6239957
Filing Date: 2001-05-29
Classification: H01L,H02H,Y02E,Y10S

Abstract:
A current limiting device, comprising:a high temperature superconductor connected to an electrical circuit, the high temperature superconductor having a critical temperature and a critical current density, the critical current density varying with an applied magnetic field;a cooling system including a device to flow a cooled gas past the high temperature superconductor to maintain the temperature of the superconductor at or below the critical temperature;a magnetic field applying device to apply a magnetic field to the high temperature superconductor to define a critical current density, the magnetic field applying device comprising a shunt coil wound around the superconductor; anda control device to control the magnetic field applying device to apply the magnetic field to the high temperature superconductor,wherein the superconductor limits current flow in response to a current flow in the superconductor greater than the critical current density, andwherein the control device includes a normally open switch connected to the shunt coil, wherein the superconductor sheds current into the shunt coil to generate a magnetic field, and the magnetic field is removed by closing the switch.