Equivalent Resistance Analysis of an Eddy Current Displacement Sensor

In this paper, a theoretical analysis of an equivalent resistance of an eddy current displacement sensor is described. The AC resistance becomes lager due to the influence of the skin effect and the proximity effect when the operating frequency of the sensor becomes higher. The equivalent electronic circuit of the eddy current displacement sensor is composed of inductance, resistance and parasitic capacitance. The inductance was calculated by using the theory of Dodd. When calculating the resistance, both skin effect and proximity effect were taken account of. The parasitic capacitance was estimated by using the experimental results. The equivalent resistance of the eddy current displacement sensor was calculated by using them all. Through experiments, we confirmed that the calculated equivalent resistance well accorded with actually measured one.