1330 MVA TURBO-GENERATORS FOR THE BELGIAN NUCLEAR POWER STATIONS.

The improvement of the coefficient of utilization is mainly the result of the increase in electrical loading. The increase in magnetic loading is significant, however, and is due to the adoption of a special distribution of the slots around the periphery of the rotor, which reduces the saturation of the rotor teeth on load and, at the same time, markedly decreases the amount of flux which penetrates radially into the stator slots and, as a result, the extra losses which this flux causes in the stator winding. The increase in stator weight is the result of several factors which acted in opposition. The use of water cooling resulted in a reduction of close to 20% of the weight of the copper, corresponding to a multiplication of current density by 2. 5. The increase in the magnetic load led to increase of the dimensions of the magnetic circuit. The requirement to limit the weight of the heaviest part from the handling point of view and the choice of an elastic mounting of the magnetic core, with respect to the frame, led to the adoption of a type of construction with separable internal and external frames.