High-speed alternating current generators

Claim 1

A high-speed gas or steam turbine driven a.c. generator comprising: a stator and a fluid-tight stator housing having bearing end-shields, magnetizing coils and stator windings enclosed in the stator housing; a windingless rotor having two or more pole units of the same magnetic polarity arranged in sequence on a common through shaft which is part of the rotor; first and second fluid bearings between the rotor, and the stator housing in the region of said end shields; one or more additional fluid bearings formed along the length of the rotor and intermediate between said first and second bearings; the additional bearings being formed at cylindrical regions of the rotor and complementary annular bearing regions of a lining of electrically and magnetically inactive material which lining is secured to stator laminae and a stator frame construction, said bearing lining being fluid tight and arranged to extend substantially over the length of the rotor; a common fluid lubricant in said first and second bearings and the additional bearings; an evaporation cooling circuit to cause cooling of the windings in the stator housing by means of an axial flow of a coolant in the stator housing, the cooling circuit being isolated from the ambient atmosphere and the bearing fluid located in an annular gap on the rotor surface so that the pressure of the bearing fluid around the rotor surface is independent of the internal pressure level of the stator housing which is itself sealed from the atmosphere.