Comparative analyses of standards temperature rise test methods for induction machines

Induction machines temperature rise measurement is certainly a common demand of customers and manufacturers. The manufacturers have to optimize the product to be competitive, while the user wants to be sure that the motor is in accordance with the insulation temperature class limit. The most accepted condition to measure temperature rise in induction motors is under full load since it simulates the real operating conditions. However, it requires the use of dynamometers and sources of same or sometimes greater power than the rated power of machine under test. Additionally the coupling of high power, high speed or vertical machines can consume considerable time and investment. For these cases it is necessary to consider the use of alternative methods to measure the electrical machine temperature. In these alternative methods the load torque applied by the dynamometer is smaller than the motor nominal torque or even no load torque applied. This paper will present a comparison between the most common induction machines temperature rise methods.