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Closed-field capacitive liquid level sensor

United States Patent

5,722,290
March 3, 1998
View the Complete Patent at the US Patent & Trademark Office
Savannah River National Laboratory - Visit the Technology Transfer Website
A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units.
Kronberg; James W. (Aiken, SC)
The United States of America as represented by the United States (Washington, DC)
08/ 408,412
March 21, 1995
The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the United States Department of Energy and Westinghouse Savannah River Company.