Jawad Faiz, Amir Masoud Takbash

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This paper addresses derating of a three-phase squirrel-cage induction motor under rotor broken bars fault. For this purpose, a winding function based analytical model is used. Different types of effective losses including core losses and Ohmic losses are estimated using a full analytical method. The relationship between the induction motor losses and load is determined and it is shown that the core losses, known as the constant losses in the motor, vary with load. A proper function based on the induced electromotive force (emf), Steinmetz coefficients and load level are introduced to show variations of losses with the induction motor load. Finally, derating is applied assuming that the motor losses in all cases must be equal to that of the healthy induction motor.

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