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.