Measurement of stray load loss in polyphase induction motors

FOR LACK of a satisfactory method of measurement, no provision is made for stray load losses in the A.I.E.E. standard efficiency tests for induction motors. These losses may amount to from 2 to 5 per cent in squirrel cage motors from 1 to 5 hp. in size, decreasing gradually with increase in motor rating until they are less than 1 per cent for motors of several hundred horsepower. Development of an easy method of measuring stray load losses would not only rectify this situation, but also would permit the losses themselves to be studied more intensively and perhaps ultimately to be reduced greatly.