Notes on internal heating of stator coils

This paper deals with the problem of internal heating of stator coils for a-c. generators, particularly those with long cores in which little heat can be conducted from the center of the machine to the ends. In such generators, the heat must pass out to the iron through the insulation, and it is important that the probable temperature difference between inside and outside of the insulation be known at least approximately. Heat conductivity coefficients for various kinds of insulating materials are given, and a method of calculating the temperature gradient described. Some examples of tests made to determine the difference in temperature between inside and outside of coil are also included.