Immune algorithm based non-intrusive efficiency determination for in-situ induction motor

On average, industrial motors operate at less than 60% of their rated load, and thus at reduced efficiency, which results in zuasted energy. The evaluation of motor efficiency enables energy savings in industry. However, because of the uninterrupted characteristic of industrial process, traditional methods cannot be used for in-situ motors. This paper proposes an immune algorithm based non-intrusive method for in-situ motor efficiency determination based on a modified induction motor equivalence circuit. Rotor stray load loss is considered in the equivalence circuit by adding an equivalent résister in series with the rotor circuit. The proposed method is verified by testing a 5 HP (3.75 kW) squirrel cage induction motor, and the results are compared with the torque-gauge method and the conventional equivalent circuit parameters estimation method using no-load and locked-rotor tests. © Institution of Engineers Australia, 2010.