Analysis of Sensor Effects for a Position Measurement System in Harsh Environments

Eddy current displacement sensors (ECDS) have been suggested as a suitable technique to measure small displacements. To model the interaction between a sensing coil and a metallic plate, a transformer based equivalent circuit model (ECM) is used. However, in harsh environment like continuous casting, large displacements and high temperatures need to be separately addressed in a standard ECM. In this paper we present an analysis of the sensor effects of an ECDS in harsh environments. We analyse the impact of cross sensitivities (CS), i.e. displacement and temperature variations, on the input impedance of an ECM and present a finite element model (FEM) that represents these CS. A special expression for the input impedance allows a better interpretation of the sensor behavior. The paper addressed a first approach to analyse sensor effects of ECDS based on an ECM in harsh environments.