Induction motors that work with unbalanced line voltages have increased losses and excessive heating. In order to maintain the operational life time of the motor the international standards recommend the derating of the motor. This paper presents a study regarding the influence of the positive sequence voltage on induction motors temperature. This study aims to determine whether the voltage unbalance factors indicated by NEMA standards and currently used in industry include the influence of the positive sequence voltage on the performance of three-phase induction motors.
