Cylindrical geometry electroquasistatic dielectrometry sensors - Dielectrics and Electrical Insulation, IEEE Transactions on [see also Electrical Insulation, IEEE

Semi-analytical models are used to simulate the response of periodic-field electroquasistatic dielectrometry sensors. Due to the periodic structure of the sensors it is possible to use Fourier transform methods in combination with collocation point numerical techniques to generate accurate sensor simulations much more efficiently than with the more general finite-element methods. The models previously developed for Cartesian geometry sensors have been extended to sensors with cylindrical geometry. This enables the design of families of circularly symmetric dielectrometers with the ‘‘model-based’’ methodology, which requires close agreement between actual sensor response and simulated response. These kinds of sensors are needed in applications where the components being tested have circular symmetry, or if it is important to be insensitive to sensor orientation, in cases where a property shows some anisotropy. It is possible to extend the Fourier Series Cartesian geometry models to this case with the use of Fourier-Bessel Series over a radius large compared to the sensor dimensions. The validity of the cylindrical geometry model is confirmed experimentally, where the combined response of two circularly symmetric dielectric sensors with different depths of sensitivity is used to simultaneously measure the permittivity of a dielectric plate and its lift-off from the electrode surface. Index Terms — Dielectrometer, electroquasistatic, cylindrical, Bessel series, parameter estimation.