A new measurement technique for the determination of the
torque-speed characteristics of induction motors is presented. "his
technique is in compliance with the IEEE standard test procedure
for polyphase induction motors and generators. It is based on the
acceleration method which is performed under no load conditions.
A fast data acquisition system is used to record the speed and other
signals of interest. The data is then processed digitally with the objective
of removing undesired extraneous signals, while preserving
the accuracy of the machine characteristics over the complete
range of speed. To achieve this objective, new and unique algorithms
to perform adaptive window-size average filtering and
numerical differentiation have been developed. Experimental tests
performed on 1-hp, 20-hp and 600-hp induction motors confirmed
that this approach has several advantages over other currently
available methods. It produces very accurate results over the full
dynamic speed range of the machine and permits precise correlation
between the switching transients on the line with the variation
of the speed signal.