A new approach for measurement of the torque-speed characteristics of induction motors

The authors present a new measurement technique for the determination of the torque-speed characteristics of induction motors. This technique is in compliance with the IEEE standard test procedure for polyphase induction motors and generators. The basic principle of this new approach consists of three main steps. The first is dynamic measurement of the speed as a function of time. The second is digital filtering of the raw speed data. Finally, the speed signal is numerically differentiated to obtain the acceleration from which the torque of the machine can be found. Experimental tests using two 20 HP induction motors confirmed that this approach is more advantageous than other methods. Also, the method produces accurate results over the full speed range of the machine in contrast to some other methods