Some problems in the standardization of temperature ratings of fractional-horsepower motors

P. H. McAuley (Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.): The desire of all concerned with the thermal rating of electrical machinery is to arrive at rational temperature limits and to specify simple and accurate methods of measurement. At the winter convention in 1939, a great deal of information on this subject was presented. Following this, AIEE Standard No. 1 has been revised tentatively to favor the resistance method for determining temperature rise and changing the limits for this method from 55 degrees centigrade to 60 degrees centigrade. In general, our experience confirms the recommendations of these earlier authors whose work resulted in this step, and. in particular those of the paper “Measurement of Temperature in General-Purpose Squirrel-Cage Induction Motors,” by C. P. Potter, published in AIEE Transactions, 1939, pages 468–72.