Methods for thermal protection of medium voltage induction motors — A review

State-of-the-art overload relays for medium voltage induction motors utilize a simple thermal model and embedded temperature sensors for the thermal protection. However, this model is too conservative and not robust to changes in the motorpsilas cooling capability. This paper reviews thermal model-based approaches and parameter-based approaches to estimate the motor temperature. Each of these general approaches will be described along with their relative advantages and disadvantages. Since most of the methods in the literature are applied to small to medium size motors, this paper discusses their applicability to medium voltage motors, as well as issues that must be addressed in order to apply them to the medium voltage induction motors.