Correlation of rating data for rotating electric machinery

THE variety and extremes of environmental conditions to which electric equipment is subjected in military aircraft in connection with the stringent performance, weight, and space requirements make it mandatory that the environmental factors be properly considered in the application of this equipment. The major effect of the environment is that of cooling which has become a problem area in high-speed, high-altitude aircraft.1¿3 For some time, the available information on cooling characteristics of electric machinery has been inadequate in its scope and was not sufficiently confirmed by tests.4¿6 Adequate and correct rating data must be made available to the airframe designer for the purpose of applying the equipment in an efficient and reliable manner. In this paper, a rating and correlation method is described as applied to blast-cooled aircraft generators, but the method is not restricted to this equipment and is adaptable to any equipment which is cooled by forced convection with gases or liquids as the coolant.