Water-cooled generator connections

The increase in rating of generating plant in the past two decades has greatly increased the problems of conducting the power away to the distribution system. The conventional arrangement of naturally aircooled busbars has reached such a size that accommodation within the machine foundations is becoming increasingly difficult, and the use of forced cooling is an obvious solution. Forced-air cooling has been used, but the experience obtained with water cooling of stator windings has led to the application of this method to the generator connections. Two systems of generator connections using internal water cooling of the conductor have been developed, and are described in the paper. The first proceeded in two stages: the double-angle conductor of a nonsegregated busbar was replaced by a water-cooled tube supported on porcelain-post type insulators, and a water-cooled phase-isolated system using epoxy-resin insulators was developed. The second system involved the use of water-cooled cables. Design aspects of the two systems are discussed, prototype tests detailed and various installations described. This application of water cooling has been satisfactory, and various problems encountered during the development have been overcome. The experience gained indicates that designs can be produced for very much larger current ratings than those of the present installations without substantial increase in space requirements, and satisfactory connections of this type can be provided for the largest generators being designed or envisaged.