Eddy Current Measuring System for Testing Conductive Objects

When testing various electrically conductive objects, eddy current measuring sensor systems are widely used. Their peculiarity consists of the possibility of testing products and measuring their parameters without contact between the sensor and the test object. As before, it is relevant to carry out work to reduce the measurement error, expand the measuring range, reduce the influence of ambient temperature, and increase the reliability of the eddy current sensor design. By changing the active and inductive resistance of the sensor, the geometric and electromagnetic parameters of the test object are evaluated or the distance (lift off) between the end plane of the sensor is determined.It is shown that the measuring range of the eddy current sensor is determined by the nonlinearity of the calibration characteristic, and the important thing is not the value of the inductance of the winding, but its change from the gap, and the introduced inductance depends on the ratio of the geometric dimensions of the winding. The following electrical parameters of the eddy current sensor are determined: inductance, active resistance, own winding capacity, introduced complex resistance. The methodology for calculating the electrical parameters of eddy current sensors allows to increase the reliability of the test results. A design technology is proposed and the main structural and electrical parameters of the invoice parametric eddy current sensor used in vibration diagnostics of rotary machines for measuring the gap are determined. Computational experiments were carried out, that made it possible to evaluate the change in the electric parameters of the eddy current sensor depending on the measured gap to the control object.