The heat paths in electrical machinery

The paper deals with methods of predetermining the temperature rise in electric machinery. Data are given of the heat conductivity of insulating materials. The methods of carrying away heat by the circulation of air are discussed, and there is given an account of experiments made to determine the amount of heat absorbed by air under various conditions as to temperature and velocity in passing over coils and through ventilating ducts. The heat conductivity of punchings in actual machines is also considered.