Comparative analyses of standards temperature rise test methods for induction machines

To measure induction machines temperature rise is no doubt a common demand of customers and manufacturers. The manufacturers must optimize the product to be competitive, while the user must be sure about the motor insulation class limit. The most accepted condition to measure temperature rise in induction motors is under full load. This condition is advantageous because it simulates real life operation on field. However, this requires for dynamometers and sources of same or sometimes greater power than the rated power of machine under test. Besides the coupling of high power, high speed or vertical machines can consume considerable time and investment. In these cases it is necessary to use alternative methods to measure the electrical machine temperature. In these methods the load torque applied by the dynamometer is smaller than the motor nominal torque or even no load torque is applied. In this paper we will present a comparison between the most common induction machines temperature rise methods.