Abstract: An electrical machine including a moveable permanent magnet configured to generate a first magnetic field. A stator including windings configured to excite a second magnetic field. A moveable inter-pole component located between the permanent magnet component and the stator, the inter-pole component comprising an array of magnetic inter-pole pieces. The speed of movement of the inter-pole component is controlled to set a magnetic gear ratio between the first and second magnetic fields. Also a gas turbine engine, propulsor or thruster incorporating the electrical machine.

Abstract: A fault current limiter comprising: an input node; an output node; a variable impedance element coupled between the input node and the output node; a multi-cycle refrigeration system, comprising a first coolant cycle for cooling the variable impedance element and a second coolant cycle, thermally coupled to the first coolant cycle, for cooling the first coolant, wherein the variable impedance element comprises Magnesium Diboride.

Abstract: Condition monitoring of an electrical machine is achieved by using electro-magnetic finite element analysis to analyse the machine based on model parameters corresponding with at least one fault condition. This allows the effect of the fault condition to be predicted. Metrology is used to recover live measurements for comparison with the predictions from the electro-magnetic finite element analysis to identify any fault signatures within the live measurements, in principle allowing those faults to be detected or diagnosed before they become catastrophic.