An improved motor replacement strategy using non-intrusive motor efficiency estimation

With increasing energy costs and a renewed focus on using energy in ways that support the environment, a structured approach is required to ensure that energy is used efficiently. Knowing the efficiency of installed motors is essential for effective motor energy management. The efficiency data can be used in the identification of opportunities for improving energy efficiency by replacing inefficient motors with high-efficiency motors and improving the motor-driven processes. In this paper, a non-invasive technique for estimating the efficiency of in-service induction motors without process interruption is presented. The motor efficiency is estimated using the non-intrusive compensated slip method. The accuracy of this technique is verified through experimental data. A comprehensive motor replacement strategy to reduce motor life cycle costs while increasing reliability is proposed. The application of energy management principles is combined with benefits that can be obtained from using energy-efficient motors. Tools for the economic analysis of the potential financial benefits of replacing motors with energy efficient motors are developed. The strategy presented incorporates benefits that can be obtained from using in-situ motor efficiency estimation. The replacement motor can be compared to the installed motor using the actual efficiency across the load profile for the application for which the motor is used. A case study of the application of the strategy is presented.