An Alternative Methodology for Quantifying Voltage Unbalance Based on the Effects of the Temperatures and Efficiency of Induction Motors

Many unbalanced voltage conditions, which produce different effects on electric equipment, are associated with the same voltage unbalance factor. This fact hinders the precise association between the values of this index and the effects of voltage unbalance. In the present study, an alternative methodology for quantifying voltage unbalance based on the effects of this phenomenon on the temperature and efficiency of three-phase induction motors is proposed. The application of the suggested methodology results in an index that contemplates the combined effects of the modules and angles of the positive and negative sequence voltages. Aiming to apply this methodology and evaluate its performance, we selected a comprehensive set of balanced and unbalanced voltage conditions and used it on a three-phase induction motor. The results show that the index obtained, when compared to the traditional voltage unbalance factors, reduces the uncertainties inherent to the quantification process of this phenomenon. In other words, it allows a better association between the values and effects of the voltage unbalance. For these reasons, this index is considered as a potential alternative that can be employed in industrial utilities and standards that deal with voltage unbalance.