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Impedance Spectroscopy

Advanced Applications: Battery Research, Bioimpedance, System Design

Ed. by Kanoun, Olfa

Open Access
eBook (PDF)
Publication Date:
December 2018
Copyright year:
2019
ISBN
978-3-11-055892-0
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Interface circuit for oil quality assessment considering dielectric losses and stray capacitances

Fendri, Ahmed / Jribi, Racem / Kanoun, Olfa / Ghariani, Hamadi

Abstract

Dielectric spectroscopy is becoming a popular technique in addition to the chemical and optical methods for oil quality assessment. It is based on the measurement of the variation of the dielectric properties of oil corresponding to the change of its chemical and physical properties. In this investigation an interface circuit for the measurement of the dielectric properties of oil is proposed using the capacitanceto- voltage conversion technique. The circuit measures the variation of capacitance of the sensor. The output voltage of the circuit is a DC voltage proportional to the capacitance of the sensor with a resolution of 5 mV/pF. The differential technique was used to eliminate stray capacitances caused by the circuit. Regression analysis has been carried out to describe a mathematical relation between the change of the capacitance and the output voltage. Simulations show a maximum relative deviation of 0.03 % for capacitance in the range of 100 pF to 1000 pF while experimental results show a maximum relative deviation of 2 % for the same capacitance range. The effects of stray capacitances and dielectric losses are also investigated. Stray capacitances decrease the measurement accuracy to 0.1 %, while the parallel resistance, which represents the dielectric losses does not affect the accuracy, if its value is higher than 10 MΩ. For resistance values lower than 10 MΩ the circuit is not stable and it is threfore not possible to estimate the capacitance value using the output voltage.

Citation Information

Ahmed Fendri, Racem Jribi, Olfa Kanoun, Hamadi Ghariani (2018). Interface circuit for oil quality assessment considering dielectric losses and stray capacitances. In Olfa Kanoun (Editor), Impedance Spectroscopy: Advanced Applications: Battery Research, Bioimpedance, System Design (pp. 93–104). Berlin, Boston: De Gruyter. https://doi.org/10.1515/9783110558920-010

Book DOI: https://doi.org/10.1515/9783110558920

Online ISBN: 9783110558920

© 2018 Walter de Gruyter GmbH, Berlin/Munich/BostonGet Permission

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