Abstract: A rotor disc assembly 10 for an AC machine includes a rotor disc 20, permanent magnets 30 and a spider 40. The rotor disc 10 has a circumferential lip 22 projecting from a surface thereof. The permanent magnets 30 are positioned in a circular array on the surface of the rotor disc 20, with constant angular pitch, and so as to lie against the lip 22. The spider includes an annular base portion 41, with a plurality of arms 42 projecting radially outwards therefrom. The spider 40 is fixed to the surface of the rotor disc 20 such that each arm 42 is between and abuts a respective juxtaposed pair of the permanent magnets 30. The arms 42 and the members 30 are each provided with cooperating wedge-shaped cross sections such that each arm 42 constrains the respective two permanent magnets 30 both axially and tangentially on the surface of the rotor disc 20.

Abstract: A method of magnetizing members of magnetizable material (210) including presenting a magnetizer head to a circular array of the members (210) mounted on a rotor plate (200) of an electrical machine. The magnetizer head includes a circular array of coils (142), each coil (142) being positioned adjacent a respective one of the members (210). A current is supplied to selected juxtaposed pairs of the coils (142) so as to set up a magnetic field. Flux of the field forms a closed loop through the pair of coils (142) and the adjacent pair of members (210), such that uncontrolled flux leakage from this loop is minimized and such that the pair of members (210) are at least partially magnetized.

Abstract: A method of controlling connection of an AC power output to a load (11) and to a power supply grid (8). The AC power output is produced by an AC power generating system which includes an AC/AC convertor (3) and which is independently operable to supply power to the load (11). Operation of the AC/AC convertor (3) for independent operation is controlled in accordance with a reference (Unr) which is generated within the system. In order to connect the AC power output to the power supply grid (8) in addition to supplying the load (11), the reference (Enr) which was derived from the AC power output voltage (Vacc) during independent operation is replaced by another reference (Irp) which is derived from the voltage (Vacg) of the grid (8) so that the AC/AC convertor (3) is controlled by that other reference (Irp) when the AC power output is connected.to the grid (8) as well as supplying the power required by the load (11).

Abstract: A rotor disc for an electrical machine is disclosed. The rotor disc comprises a series of magnetisable members arranged in a circumferential series on a surface thereof and against peripheral retaining structure of the disc. The disc also includes a retainer fixable to the surface and arranged for assisting in retaining the members at least axially on the surface when so fixed. The retainer is arranged to abut at least one of a substantially circumferentially and substantially tangentially extending, radially inner part of each member and thereby to provide the axial retention.

Abstract: A generating set includes an engie driven generator (PGM) having two sets of stator windings (Ga and Gb). A bi-directional AC/DC converter (BCo) has its AC input connected to a junction between the two sets of stator windings (Ga and Gb) and its DC input connected to a number of the generator (PGM) is converted into an intermediate DC link by a convertor (Col) to produce an output for a load Lo. In normal operation of the system, an emf generated in one (Ga) of the sets of stator windings is rectified by the bi-direcitonal converter (BCo) to charge the energy storages (ESI-ESN) whilst the remainder of the generator output is fed through the converter to the load (Lo). In the event of a stepped increase in the load demand, the bi-directional converter (BCo) is operated to feed energy from the storage devices (ESI-ESN) to the stator windings (Ga) of the generator (PGM) to impart a driving torque to the generator rotor to accelerte the rotor to meet the increased load demand.

Abstract: A toroidal AC generator includes an outer casing and an annular stator core of ferromagnetic material which is encased in a hollow annular cover of plastics material and which is fixed to the casing between the discs of a twin disc rotor. Each rotor disc carries a circular array of alternately polarised permanent magnets which face the stator core. The hollow annular cover is a two-part moulding and is formed of radially inner and outer ring portions which are joined by circular arrays of radial ribs which extend across the opposed radial faces of the annular core and form open-ended radial passages for the electrical phase windings which are wound around the cover. The ribs project radially beyond the radially outer ring portion and form hooks around which a winding may be retained temporarily during winding.

Abstract: An electric power generating set which automatically varies its speed to match load variations at any time includes an engine driven generator G which provides a positive, Ga and a negative, Gb AC output voltage each of which is rectified by a respective rectifier Re3a, Re3b. Each rectifier Re3a,Re3b has one terminal connected to a common neutral line N. The DC output voltage of each rectifier Re3a, Re3b is boosted in a respective booster circuit which also has one terminal connected to the neutral line N. The combined output of the two booster circuits, Va+Vb is fed to an Inverter IN which converts it to the AC power output of the generating set. A DC load current between the booster circuits and the inverter IN is monitored and used to provide a speed demand feedback signal Srs to the speed control of the engine EN.

Abstract: An AC generator comprises a rotor 25 within a stator 24. The rotor carries a fan 27 at one end of the stator. The fan 27 is within a casing 30 which forms volume discharge passages 32. The fan 27 has blades 31 which project from the hub 28 at an angle which is oblique to the radial whereby those blades 31 trail the radial. The stator windings 23 form terminal leads 34 which are led from the end of the stator 24 remote from the fan 27. A circumferential array of cleats 35 which each have the form of a comb, support and guide the terminal leads 34 circumferentially, spaced from one another, to a certain location at the top from which the leads are taken and connected to terminals above. Those terminals are formed by the lower ends of busbars (56 to 58, 61 to 69) which extend through and which are supported by a structural panel of insulating material which forms an insulating barrier between the ends of those busbars.