Performance assessment of the rotational speed measurement system based on a single electrostatic sensor

Rotational speed is a key parameter for condition monitoring and control of rotating devices in many industries. This paper presents a novel measurement technique using a single electrostatic sensor coupled with autocorrelation signal processing algorithms. The characteristics of the electrostatic sensor are analyzed through Finite Element Modeling. Experimentation based performance assessment of the system for the speed measurement of shafts made of different materials, including polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC) and polyamide (PA) is reported. Effect of the size of the shaft is observed and quantified. Experimental results obtained on an experimental test rig suggest the measurement system is capable of producing repeatable rotational speed measurement with a maximum error of ±0.5% over the speed range of 600 to 3000 RPM (revolution per minute). The system performs better under the conditions of higher rotational speed and larger rotors.