A Digital Torque Angle Transducer

This paper describes a digital transducer which displays the torque angle of a synchronous machine operating in motoring or generating modes. The transducer can also provide a torque angle feedback signal for digital control applications in power systems. A signal indicating the rotor position, which is detected using a photo device, is compared with the terminal voltage reference, and the phase shift indicating the torque angle is processed to provide a digital display. Though very simple circuits have been used in building the transducer, very accurate and stable readings are obtained. The sampling technique used in the counter makes the reading independent of minor variations in line frequency. Experimental results are presented to indicate the performance of the circuit. The transducer can be modified to indicate angular speed.