Abstract: A P-bar excitation system employs a generator having means for adjusting the voltage and current available from the P-bars. In some installations, the direct output of the P-bars can be connected directly to the rectifier and control circuit for development of dc excitation power. This permits elimination of the conventional excitation transformer and overall simplification of the excitation system. The voltage and current are adjusted using paired P-bars per phase, wherein each pair of P-bars is connected in series, and angularly displaced from each other about the inner circumference of the armature to attain a vector sum of voltages yielding and desired voltage per phase. In another embodiment, the generator magnetic flux, or equivalently, the number of armature turns is adjusted to yield the desired P-bar voltage and current.

Abstract: An excitation system of a large dynamoelectric machine includes an excitation transformer having a liquid coolant system. The coolant system of the transformer is supplied with a liquid coolant, preferably from an existing source of de-ionized water, thereby permitting a smaller transformer to be used and/or the output rating of the transformer (and ultimately the output rating of the machine) to be increased, while using the same size transformer. The transformer may be disposed separate from, yet closely proximate, the machine.

Abstract: A simplified static excitation system for a fluid-cooled dynamoelectric machine comprises a potential source excitation winding disposed in the stator slots, the winding being responsive to the fundamental frequency of the generator air-gap magnetic flux. The excitation system further comprises transformer means coupling the excitation winding to rectification means which is coupled to the rotating field windings so as to provide direct electric current thereto. The transformer means is preferably disposed within the cooling fluid of the machine.