Estimating the effects of harmonic voltage fluctuations on the temperature rise of squirrel-cage motors

A preliminary analysis of the effect of randomly varying harmonic voltages on the temperature rise of squirrel-cage motors is presented. The stochastic process of random variations of harmonic voltages is defined by means of simple statistics (mean, standard deviation, type of distribution). Computational models based on a first-order approximation of the motor losses and on the Monte Carlo method yield results which prove that equipment with large thermal time-constant is capable of withstanding, for a short period of time, total harmonic distortions larger than 5%.<
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