Frequency response and bandwidth of an electrostatic flow probe

Abstract This paper is the continuation of a theoretical study presented earlier [J.B. Gajewski, Electrostatic, inductive ring probe bandwidth, Meas. Sci. Technol. 7 (1996) 1766] and presents results of laboratory experiments upon an electrostatic (inductive), non-intrusive ring probe, as used for measuring the net electric charge or mean mass flow rate (or volume loading – concentration), or both, of particulates in pneumatic transport pipes. The goal of that experimental work was to obtain the frequency response characteristic and bandwidth of the probe. An AC analysis in the output of an equivalent circuit of the probe and preamplifier, representing a model of this system, were also made to get the frequency response of the modelled probe–preamplifier circuit over a range of frequencies. In this paper are presented the results of laboratory tests upon the frequency response and bandwidth of an actual electrostatic flow probe, which is used in everyday experiments and research. The experiments were conducted under real laboratory conditions that are very similar to those one can encounter in industry. The frequency response characteristics were obtained that permit the probe bandwidth to be determined. The characteristics resulted from AC analyses of the modelled equivalent circuit of the probe and preamplifier are in good agreement with experimental ones.