A novel method for load testing and efficiency measurement of three-phase induction motors

This paper describes a novel method of fail load testing for temperature rise and efficiency evaluation of three-phase induction motors. A synthetic loading technique is used, without the need to connect a load to the machine´s drive shaft. The new method uses a digital signal processor controlled power electronic inverter to continually accelerate and decelerate the induction machine, while using a new real time data acquisition system to accurately determine and record the machine´s performance. The method proposed considerably reduces the testing time compared with conventional methods of temperature rise and efficiency measurement and the accuracy of the result is maintained. Simulation using a hypothetical machine is used to confirm the technique for efficiency evaluation.