The Design and Performance of Modern, Large Turbine Generators [includes discussion]

Advancements in the art of design and construction of large turbine generators have brought about marked improvements in the familiar designs of these machines. New methods of cooling give machines new and different characteristics. The physical sizes of conventionally cooled generators are largely determined by their heat-dissipating ability. Their efficiencies are not greatly influenced by their physical size. Conductor-cooled generators, on the other hand, have such increased heat-dissi-pating ability that their size is determined almost entirely by other factors. The balance of such economic considerations as generator size and efficiency tends to govern the design of machines with this type of cooling. Losses are an interrelated function of machine size, hydrogen pressure, coolant pumping pressure, and the geometry of the coolant passages. The choice of hydrogen pressure for maximum capability is affected by such performance characteristics as efficiency, short-circuit ratio, and capability in air. It is shown how these various factors are related and the way in which their influence is brought to bear, first on the choices made while the generator is being designed and, second, on the performance of the generator after it is installed.