Non-intrusive method for induction motor field efficiency estimation using on-site measurement and modified equivalent circuit

This paper proposes a non-intrusive method for low-voltage induction motor field efficiency estimation based on the modified equivalent circuit which includes the additional stray-load loss and friction and windage loss parameters for improving accuracy. This method focuses on a simple means without the expensive testing. This paper presents the use of on-site measurement data and speed measurement scheme using the motor current signature analysis (MCSA) incorporated with the proposed adaptive optimal design algorithm based on optimization process to evaluate the optimal parameters of modified circuit. This proposed method has been verified by using the shaft torque method results of low-voltage 2.2 (6-pole) and 4 kW (4-pole) motors. The results indicate that the estimated motor field efficiencies have sufficient accuracy (within 2 %) during the normal operations. Therefore, this simple procedure can provide the useful information for energy audit.