Thermal model based digital relaying algorithm for induction motor protection

Abstract

Thermal models can be used to protect induction motors from excessive overheating resulting from overloading, failure to start, unbalance and frequent starting. Such a model is adopted for use in a relaying algorithm. The developed algorithm accurately calculates the change in motor temperature and hence, protects the motor from excessive overheating. The lab results, included in this paper, of motor temperature during a loading cycle show high correspondence with the established thermal model.