Abstract: A superconducting electrical machine 1 such as a ship's engine has a rotor 10 and a stator 30, the rotor having superconductive windings 15. The rotor 10 includes an additional normally-conducting winding 55 in parallel to the superconducting winding 15 but not normally connected. In the event of a fault in the superconducting winding 15, the additional winding 55 can take a sufficient current to run the engine to maintain mobility of the ship. Moreover, while this normally-conducting operation is under way, the heat generated warms the cooled engine ready for maintenance.

Abstract: In a DC electrical power system used in an aircraft, an earthing arrangement is provided between electrical power supply rails in the form of a pair of capacitors with a mid electrical voltage earthing point, having an earthing path, in which electrical resistance is provided to limit electrical current flow and therefore allow continued operation despite the earth fault.

Abstract: A generator control arrangement for an electrical power generator, the arrangement comprising a controller arranged to regulate output voltage from a generator to a target value, the controller including a voltage comparator for comparing a presented voltage with a desired output voltage, the presented voltage derived in a transfer comparator by combination of a reference voltage value and an error value between a reference electrical current value and a measured electrical current value subject to a processor gain whereby the processor gain can be specifically set at zero to enable control by voltage or the processor gain can be specifically set at greater than zero to enable control by electrical current.

Abstract: In DC electrical power systems used for example in aircraft typically an earthing arrangement is provided between electrical power supply rails in the form of a pair of capacitors with a mid electrical voltage earthing point. In such circumstances in previous arrangements an earth fault will have low impedance to the ground and therefore have excess electrical current flow. By aspects of the present invention electrical resistance is provided in the earthing path to limit electrical current flow and therefore allow continued operation despite the earth fault.

Abstract: Electrical power generation through a number of generators has efficiency benefits particularly with regard to aerospace applications. However, should parallel operation of these generators be interrupted through malfunction of one of the generators or otherwise, care must be taken in order to maintain the rate of electrical voltage for system demands. Previously it has been known to control parallel operating electrical power generators respectively through voltage control and electrical current control regimes so at least some of the generators must be able to operate under both regimes. This necessitated separate control loops which at least is inconvenient. By providing a common voltage comparator which receives a reference electrical current Vtgt from a transfer comparator 23 it is possible to achieve voltage as well as electrical current control.