Loadless full load temperature rise test for three phase induction motors

This paper introduces a new method for measuring the full load temperature rise of three phase induction motors. The method is very simple. cheap and reliable. It does not require a mechanical load to be coupled to the motor shaft, as in the conventional method. Also, it does not need any auxiliary machines or special power electronics to generate the two frequency supplies, as needed by the dual frequency method. The method is simply to run the motor at no load without any thing coupled to the shaft but with the supply voltage slightly higher than the rated voltage of the motor. This causes the motor to draw from the supply a no load power higher than that drawn at rated voltage. The value of this power can be controlled by changing the applied voltage to simulate the full load conditions on the motor. The results obtained in this study showed that an input voltage of about 120\% of the rated voltage of the motor is a suitable value to cause the full load losses to occur in the motor body, and hence, the full load temperature rise is obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.