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: Apparatus for containing liquid coolant within a liquid cooled transformer includes a vessel having opposing sides for forming a chamber. The chamber is prevented from decreasing below a predetermined volume limit when compressive force is applied to the vessel by providing separation elements which are coupled to at least one of the sides and extend into the chamber for contacting the other side when the limit is reached, thereby preventing further volume reduction of the chamber. When a liquid under pressure is supplied to the chamber the vessel tends to expand, such that when the apparatus is disposed between laminations of a core of a transformer for cooling the transformer, force is exerted on the laminations, thereby ensuring that the laminations do not loosen under adverse operating conditions.

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 coil assembly includes a first winding for circumferentially surrounding at least a portion of a leg of a transformer core, a second winding spaced from and circumferentially surrounding at least a portion of the first winding, first supports, such as axially extending insulative rods, disposed between the first and second winding, for inhibiting axial motion of the second winding relative to the first winding and a second support disposed about at least a portion of the outer periphery of the second winding for inhibiting radial motion of the second winding relative to the first winding. Encapsulating material, such as an epoxy resin having glass fibers disposed therethrough, is disposed between the first winding and the leg, between the first and second winding and disposed about the second support for forming a monolithic structure. In a transformer including such a coil assembly, the leg and conductors forming the windings may be fluid cooled.

Abstract: A stator core for a dynamoelectric machine includes two pairs of dovetail slots disposed at respective predetermined radial positions in each armature slot. All stator slots contain armature bars. A few equally spaced stator slots also contain "P" bars atop or radially inward from armature bars. Wedges are installed in the radially outer dovetail slots of stator slots containing only armature bars. Wedges are installed in radially inner dovetail slots in stator slots containing both armature bars and "P" bars.