No load method of estimating stray load loss in small cage induction motors

The author refers to the principal methods that have been used for measuring losses in cage induction motors and their assessment by Schwarz (1964) and later investigators. Some claims have been contradictory and almost the only consensus is that the existing BS 4999 method is inadequate for small motors; no satisfactory alternative has been suggested. The author describes a no load test method which is simpler to perform and has fewer theoretical objections than other methods that have been used previously. Typical test results for three motors in the size range 0.25 to 5 kW are shown