In this paper, the on-service non-invasive efficiency estimation using equivalent circuit (EC) for three-phase induction motor replacement program is presented and investigated. The motor equivalent circuit parameters (ECPs) are estimated by particle swarm optimization (PSO) using measurement data during on-service condition. Then, the non-invasive equivalent circuit method (NIECM) for motor efficiency estimation can be performed using the PSO based motor ECPs estimation. In the proposed NIECM, the induction motor ECPs are estimated by using the measured motor voltage, current, real and reactive powers, power factor, and speed. Therefore, the motor efficiency can be non-invasively analyzed. The developed NIECM software has been tested with nine motors in the laboratory and investigated with five motor replacement programs. The experimentation results of the proposed NIECM, comparing to conventional slip method (SM) and current method (CM), are illustrated and discussed. Among NIECM, CM, and SM, the proposed NIECM provide the minimum error in efficiency estimation comparing to the shaft-torque method. Therefore, the proposed NIECM can, potentially and conveniently, be applied for the on-service non-invasive three-phase induction motor efficiency estimations, with the reasonable mismatch to the laboratory shaft-torque method.
Keywords
equivalent circuit method, current method, non-invasive induction motor efficiency estimation, particle swarm optimization, slip method.