Phasor visualizer: a general purpose instrument for induction motor drives

This paper describes an instrument for the real-time visualization of the quantities necessary for analysis, diagnosis and investigations of AC machine drives on an oscillographic display. The instrument needs no shaft position or speed sensor, it uses exclusively the acquired stator currents and voltages and provides information, in electrical and visual form of: stator and rotor flux; torque; reactive power; torque current; flux current; torque angle; and slip frequency. The measuring instrument is based on analogue signal processing techniques. Its main fields of application are: monitoring systems; control units; as a research tool for induction motor drives; and in test shops. Practical results of the implementation are presented and discussed