A method, system and device for an electric generator comprising dynamically selectable number of generator disk assemblies.

An electric machine has a stator and a rotor which is separated from the stator by an air gap. The rotor has at least one first rotor body, which has a first group of permanent magnets, and at least one second rotor body, which is arranged at an axial distance from the first rotor body) and has a second group of permanent magnets. A rotor shaft is coupled to the first rotor body and the second rotor coaxially within the first rotor body and the second rotor body so as to transmit a torque. At least the first rotor body is mounted on the rotor shaft so as to be rotatable relative to the second rotor body against the effect of a first torsional stiffness by means of a mechanical field-attenuation mechanism.

A gas turbine engine includes: first spool including first compressor and first turbine drivingly coupled by first main shaft; second spool including a second compressor and second turbine drivingly coupled by second main shaft; combustion equipment; electrical machine arrangement including: first rotor drivingly coupled to first main shaft and carrying array of rotor elements; second rotor drivingly coupled to second main shaft and carrying array of rotor elements; and stator arrangement including array of stator coils arranged around an axis, axis being coaxial with an axis of rotation of first rotor and an axis of rotation of second rotor. Stator arrangement is axially translatable relative to first and second rotors, between: a first axial position in which array of stator coils interacts with array of rotor elements of first rotor; and a second axial position in which array of stator coils interacts with array of rotor elements of second rotor.

A gas turbine engine includes: first spool including first compressor and first turbine drivingly coupled by first main shaft; second spool including a second compressor and second turbine drivingly coupled by second main shaft; combustion equipment; electrical machine arrangement including: first rotor drivingly coupled to first main shaft and carrying array of rotor elements; second rotor drivingly coupled to second main shaft and carrying array of rotor elements; and stator arrangement including array of stator coils arranged around an axis, axis being coaxial with an axis of rotation of first rotor and an axis of rotation of second rotor. Stator arrangement is axially translatable relative to first and second rotors, between: a first axial position in which array of stator coils interacts with array of rotor elements of first rotor; and a second axial position in which array of stator coils interacts with array of rotor elements of second rotor.