True level - analog capacitive sensing - February 2006

Level Measurement & Control

True level - analog capacitive sensing

February 2006 Level Measurement & Control

The Rechner KF Series True Level capacitive measuring system for analog level measuring is designed to provide precise measurements at any level - not just at a couple of specific points the way the old fashioned limit switches operated but at all points in between the sensing range.

Available from ASSTech Process Electronics & Instrumentation, the new KF automatically compensates for the dielectric constants of the material being controlled. This means that the measured filling height is not dependent on the material being sensed and the sensitivity never needs to be adjusted. This is a great advantage when different products, with different dielectric constants, are processed in the same material handling equipment.

The analog probe has a reference system (R), a measuring range (M) and a non-active range IB at the top of the probe for mounting inside a tank. The reference detector (R) is located in the bottom 85 mm of the probe and determines the dielectric characteristics of the material relaying this information to the measuring range (M). This will automatically calibrate the sensor every time the material is changed from powder to paste to pellets etc - or if changes in temperature or humidity occur in the environment.

The measuring range of the sensor can be as long as 1885 mm and can be provided with digital set points to customer specifications, or can be supplied with an analog signal over this range. The inactive range (IB) has a minimum length of 30 mm at the top of the probe and provides a mounting area for metallic clamps or brackets.

The Per Level probe can be provided with one, two or three fixed switching points. The position of the points is determined by the customer, but a separation between points of 50 mm minimum must be maintained. Smaller distances are possible on request, depending upon the characteristics of the medium and the geometrical configuration of the container.

* Level measurement in containers and pipes of metal or conductive material with a diameter up to 2 m (for non-metallic containers an additional electrode is necessary).

* Suitable for bulk goods, pastes or liquids with an Er > 1,2.

* Due to its large measuring capacity it is also suitable for non-homogenous media.

* With the corresponding type of mounting, the sensor is virtually independent of the discharge cone.

* Deposits on the sensor cause negligible influence on the measurement.

* Applicable for product temperatures between -40 and +180°C.

* Output options of 0 to 20 mA, 4 to 20 mA, 0 to 10 V, 0 to 10 kHz.

For more information contact Anastas Schnippenkotter, ASSTech Process Electronics & Instrumentation, 011 794 7057.

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Level Measurement & Control

True level - analog capacitive sensing

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