An economical method for induction motor field efficiency estimation for use in on-site energy audit and management

This paper proposes an economical method that can help the plants to make right decision in replacing the inefficient induction motors with more efficient ones. This method focuses on the field efficiency of motors without the needs for removing motors and measuring the output power. The use of a few sets of measured data from field test coupled with the genetic algorithms for evaluating motor equivalent circuit instead of using the no-load and blocked-rotor tests is proposed. To illustrate how well the estimated efficiency matches that of calculated obtained from the standard evaluations, the results of various induction motors rating up to 100 hp are presented. Test results indicate that this method has a high accuracy, then it is suitable for conducting on-site energy audits of motors in order to project cost savings and payback and to support a confidence decision regarding the investment in higher efficiency motors.