Abstract: There is provided an electrical switch comprising a length of superconducting material. In some forms the electrical switch is configured to be controlled between a low-resistance state and a higher-resistance state by the selective application of one or more switching mechanisms. In the higher-resistance state, current flowing through the length of superconducting material may approach the critical current of the length of superconducting material, may be substantially equal to the critical current or may be greater than the critical current. In some forms, the length of superconducting material is a length of high temperature superconducting material.

Abstract: The invention relates to a superconducting electrical switch. The switch comprises two parallel branches of superconducting material in a loop, and a magnetic field generator which generates a time-varying magnetic field through the loop in a direction generally parallel to the axis of the loop. The magnetic field generator is selectively activated and de-activated to switch the electrical switch between a low-resistance state and a higher-resistance state. In the low-resistance state, there is no magnetic field through the loop and transport current flows through the loop. In the higher-resistance state, a magnetic field through the loop induces a screening current such that the sum of the transport current and the screening current is substantially equal to the critical current or is greater than the critical current of the superconducting material. The switch may be used in, for example, a rectifier or fault current limiter.

Abstract: A superconducting circuit having: a charging loop; a load loop including a superconductor; a superconducting connection which is simultaneously part of the charging loop and the load loop; and a controller to control a state of the connection between a first and second conductive states. In both the first and second states the connection is in a superconducting state, but a resistance or impedance of the superconducting connection is higher in the first conductive state than in the second conductive state such that the superconducting circuit is configured to induce flux flow between the charging loop and the load loop when the connection is its first conductive state, and inhibits flux flow between the charging loop and the load loop when the connection is its second conductive state; in particular wherein the superconducting connection operates in a flux flow regime in the first conductive state.

Abstract: A superconducting circuit having: a charging loop; a load loop including a superconductor; a superconducting connection which is simultaneously part of the charging loop and the load loop; and a controller to control a state of the connection between a first and second conductive states. In both the first and second states the connection is in a superconducting state, but a resistance or impedance of the superconducting connection is higher in the first conductive state than in the second conductive state such that the superconducting circuit is configured to induce flux flow between the charging loop and the load loop when the connection is its first conductive state, and inhibits flux flow between the charging loop and the load loop when the connection is its second conductive state; in particular wherein the superconducting connection operates in a flux flow regime in the first conductive state.