An uninterruptible power supply system has a regulated power source, an electrical generator electrically interconnected to the regulated power source, an engine having a main shaft integral with or coupled to the shaft of the electrical generator, a rotating rectifier mounted onto a shaft of the electrical generator, a mains power supply, a switch connected between the electrical generator, the mains power supply and a synchronous machine of the regulated power source, a synchronous generator, and an uninterruptible load. The regulated power source has a housing, a synchronous machine, a synchronous generator, and a flywheel sharing a common shaft. The electrical generator has a shaft coupled to a combustion engine. The switch transfers power from the synchronous machine to the electrical generator to cause the electrical generator to rotate its shaft or the main shaft of the engine. A short-stop load is supplied power from the electrical generator.

The hollow rotor shaft for a rotating electrical machine includes two parts. A first part includes a first hollow cylindrical element and a second part includes a second hollow cylindrical element, whereby sections of a first end of the first and second elements are in contact and secured by securing means.

The hollow rotor shaft for a rotating electrical machine includes two parts. A first part includes a first hollow cylindrical element and a second part includes a second hollow cylindrical element, whereby sections of a first end of the first and second elements are in contact and secured by securing means.

A resistor pack assembly including an anti-rotation housing. The anti-rotation housing includes a first surface, a second surface opposite the first surface, one or more anti-rotation lugs extending away from the first surface, and an internal cavity extending from the second surface into the anti-rotation housing towards the first surface. The resistor pack assembly also including a positive rail located at least partially within the internal cavity, a negative rail having an inner circular face and an outer circular face located radially outward from the inner circular face, and an insulator ring is interposed between the second surface of the anti-rotation housing and the outer circular face of the negative rail.

A rotary electric machine includes a stator with a stator winding, a rotor with a field winding supported for rotation about a rotation axis relative to the stator, and an excitation winding. The excitation winding is fixed relative to the rotor and is electrically connected to the field winding. The rotor defines a coolant channel having an inlet and an outlet. Liquid coolant enters the inlet and flows outwardly through a portion of the excitation winding to conduct heat away from the excitation winding. Generators, aircraft electrical systems, and methods of cooling rotary electric machines are also described.

A method for manufacturing a main rotor for a generator is provided. The method includes printing at least part of a rotor shaft by a three-dimensional printing process. The step of printing at least part of the rotor shaft includes printing a plurality of closed outlets and a plurality of open outlets. A rotor core is printed by the three-dimensional printing process. The step of printing the rotor core includes printing a plurality of liquid coolant conduits that extend through the rotor core and fluidly connecting the plurality of liquid coolant conduits to the plurality of closed openings.

A method for manufacturing a main rotor for a generator is provided. The method includes printing at least part of a rotor shaft by a three-dimensional printing process. The step of printing at least part of the rotor shaft includes printing a plurality of closed outlets and a plurality of open outlets. A rotor core is printed by the three-dimensional printing process. The step of printing the rotor core includes printing a plurality of liquid coolant conduits that extend through the rotor core and fluidly connecting the plurality of liquid coolant conduits to the plurality of closed openings.

A main field connection to connect to a main field winding has a semi-cylindrical portion with an axially thicker outer surface, an axially thinner inner surface, with an aperture. An extending portion extends from the semi-cylindrical portion to a remote extending end. The remote extending end extends for a first axial distance. The axially thicker portion of the semi-cylindrical portion extends for a second axial distance. A ratio of the first axial distance to the second axial distance is between 0.65 and 1.4. A rotating assembly, a generator and a method are also disclosed.

An excitation system (15) is disclosed for providing excitation to a main rotating electrical machine (2). The excitation system comprises an exciter (50) and an auxiliary generator (52). The exciter and the auxiliary generator have separate stator cores (14, 18) and share a common rotor core (16). The common rotor (16) core may be located between the two stator cores (14, 18). This may help to optimize space, improve material usage and reduce the total rotating mass. A mounting arrangement for the common rotor core is also disclosed.

A power supply system includes a regulated power source that has an a synchronous machine, a flywheel with the shaft connected thereto, an electrical generator electrically connected through a switch to the synchronous machine of the regulated power source, an engine having a main shaft coupled to the shaft of the electrical generator, a power supply, and a switch connected between the electrical generator, the power supply and the regulated power source. The switch transfers power from the regulated power source to the electrical generator so as to cause the electrical generator to rotate the shaft in order to rotate the shaft of the engine during engine start-up.