A non-intrusive in-service motor efficiency estimation technique

Abstract

Optimising the energy use of electric motors presents a significant opportunity for reducing energy consumption in industry. A need exists for methods of accurately estimating the efficiency of motors without interrupting the motor driven process. This study describes the development of an accurate non-intrusive efficiency estimation technique for in-service induction motors. This method is based on a non-intrusive compensated slip method. A new motor speed estimation technique based on vibration signature analysis is developed and applied in the proposed efficiency estimation technique. The performance of this method is verified through experimental data. Six other efficiency estimation techniques are implemented in this work. Their practical performance is compared to the proposed non-intrusive compensated slip technique. The proposed method of estimating motor efficiency is found to be accurate and easy to implement. The robustness of the non-intrusive compensated slip method to variations in the supply voltage is evaluated. The technique is robust to under-voltage and over-voltage power system conditions. A comprehensive motor management strategy to reduce motor life cycle costs while increasing reliability is presented. This is an integrated approach based on the application of the speed and efficiency estimation techniques described in this study.