P2.12 Equivalent Circuit Model and Evaluation of Inductive Conductivity Sensors
- SMSI 2020
(did not take place because of Covid-19 virus pandemic)
- SMSI 2020 - Sensors and Instrumentation
- P2 Sensors and Measurement Systems for Physical Quantities
- J. Förster, M. Mallach, T. Lange - KROHNE Innovation GmbH, Duisburg (Germany), M. Vogt - KROHNE Messtechnik GmbH, Duisburg (Germany)
- 248 - 249
Inductive sensors allow for contactless measurement of the electrical conductivity of liquids. A first magnetic coil is used for inducing an eddy current into the liquid, and this current is measured with a second coil. In this contribution, an equivalent circuit model is presented, including also a parasitic direct coupling and the liquid’s electrical permittivity. It will be shown analytically and with measurement results that the real part of the ratio of the measurement voltages has to be evaluated and that a trans-impedance amplifier with a small input-impedance has to be used for accurate measurements.