Page 4 of catalogue Capacitive level measuring systems of Rechner Industrie-Elektronik GmbH

TECHNOLOGY
Capacitive level measurement has proven itself as one of the most universal level measurement principles. The reason for this is the possibility of the measurement of almost all products, no matter if liquids, bulk materials or pastes. This capacitive level measurement is based on the generation of an electric field between container and probe. Herewith a measuring capacitor is formed. Within this measuring capacitor the filling material works as a dielectric that changes its capacity. These capacity changes are electronically evaluated and are converted in to the desired output signals.

Three-Electrode-Principle The measurement systems now introduced all operate according to the three-electrode-principle. With the three-electrode-principle the container or an additional electrode serve as a counter-electrode to the probe electrodes. For this reason it is necessary with this system that the container is of a conductive material or a “substitute electrode” is fixed to the container wall, e.g. copper foil. This principle allows almost total elimination of the undesirable parasitic capacities and their effects, which inevitable appear in the practical operation, (e. g. generated via the probe connection cable – evaluation unit). on the basis of the patented circuit principles, outstanding parameters are achieved and the solution of exceptional applications are possible, e. g. multiple measurements and the DC-compensating analogue measurement (DC = dielectric constant).

The basis system In principle the level measurement consists of Probe + Connection Cable + Electronic Evaluation Unit

Probe The probe is a passive component part with an insulating outer cover. Standard housing: optional: GFK (glassfibre reinforced plastic). outer diameter 16 mm with outstanding mechanical properties. Recommended for use in applications with bulk materials or viscous materials. other plastic housings are available on request, such as PE, PVDF, PTFE. PEEK for use in the food industry, pharmaceutical and chemical industry. Also recommended for use in applications with non viscous fluids.

Electronic Evaluation Units Available options Limit value evaluation units Analogue evaluation units with 1 2 4 4n•4 measuring positions. - with fixed limit value switching points. - or/and with variable limit value switching points. with automatic DC-compensation

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RECHNER Industrie-Elektronik GmbH • Gaußstraße 8-10 • D-68623 Lampertheim • Tel. (0 62 06) 50 07-0 • Fax (0 62 06) 50 07-36 • e-mail: info@rechner-Sensors.de • www.rechner-sensors.com

All specifications are subject to change without notice. (10/2008)