Temperature rise values for D-C machines

THE RESULTS of heat run tests made jointly by the Allis-Chalmers Manufacturing Company, Century Electric Company, General Electric Company, Reliance Electric and Engineering Company, and Westinghouse Electric Corporation on a motor exchange program involving motors at 1750 rpm, 40 degrees centigrade open, from 1/2 to 50 horsepower, were reported in a previous article.¹ It was recommended that Table I of the American Standards Association C-50 Standard² be expanded, using values derived from the results of tests, to cover short-time rated motors and to include limiting values of temperature rise by the resistance method corresponding to existing values for the thermometer method for all windings.