Spectroscopic impedance measurement front-end for applications in industrial processes

Abstract

The determination and differentiation of various materials is of great interest in numerous applications. For this purpose, spectroscopic impedance measurement systems are applied. The frequency dependent impedance analysis enables a detailed material investigation and an assessment of its composition e. g. the moisture content. By applying impedance measurement systems in industrial environments conditions as high temperatures, high pressures or vibrations have to be considered. In this paper we present a front-end topology intended to be used for frequency spectroscopic based measurement systems, deployed in industrial environments. The impedance measurement capability of the proposed system is investigated by means of a realized prototype. We present results obtained for measurement frequencies up to 50\hspace{0.1667em}\text{MHz} and address calibration strategies, which improve the robustness. The measurement electronics is also characterized over the environmental temperature range.

ECT in a large scale industrial pneumatic conveying system

“…In the presented sensor setup this effect was minimized by a suitable routing and separation of the transmission lines. For arbitrary line lengths or varying frequencies also impedance matched designs [41] have been studied, which can be relevant for the application of impedance spectroscopic measurement techniques [17,42]. Yet the low-Z measurement circuitry remains favourable due to the shunting of parasitic capacitances.…”

“…This is for example the case in pneumatic conveying, where the particulate matter causes abrasion on the sensor. Publications on electrical tomography systems cover all aspects of these measurement systems such as the sensor design [13][14][15], and the measurement electronics [16,17]. The bulk of publications can yet be found in the field of signal processing and image reconstruction methods [18].…”