Rotational speed measurement using electrostatic sensors and correlation signal processing techniques

Rotational speed is a key parameter for the condition monitoring and control of rotating equipment such as generators, electromotors, centrifugal and machine tool spindles. This paper presents the principle and application of electrostatic sensors and correlation signal processing techniques to real-time measurement of rotational speed. Experimental tests were conducted on a test rig under a range of conditions. The results suggest that the operability and accuracy of the measurement system depend on a number of factors, in particular, the distance between the electrodes and the surface of the rotating equipment. The system performs better under higher rotational speed conditions as more electrostatic charge is produced on the rotating surface.