Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1995-01-09
1996-08-13
Wieder, Kenneth A.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324664, 324671, 324689, 73304C, 340620, 361284, G01R 2726, G01F 2326
Patent
active
055460054
ABSTRACT:
A continuous liquid level measuring system having a guarded capacitance probe and related drive circuit for providing accurate level measurements, even when measuring the level of ionic and highly viscous fluids. The capacitance probe has two parallel electrodes, each constructed of a half-tube section, that are separated from each other by an insulated guard wire. The probe is excited by a 1 MHz excitation signal applied across the electrodes. The current through the electrodes is a function of the capacitance between the electrodes, which is affected by the relative permitivity of the surrounding liquid. The effects of highly viscous ionic liquids that adhere to the probe are reduced by exciting the guard wire with a guard signal that is 180.degree. out of phase from the probe's excitation signal. The guard signal changes the electric field existing in the space adjacent the junctions of the two electrodes to reduce any liquid coating effects on the level measurement. The capacitance probe is connected to a capacitance measurement circuit through at least one 1:1 ratio pulse transformer for isolation, effectively eliminating the effects of noise currents on the probe's capacitance. Preferably, a second pulse transformer is provided to isolate the guard wire.
REFERENCES:
patent: 2852937 (1958-09-01), Maze
patent: 3496460 (1970-02-01), Martin
patent: 3710244 (1973-01-01), Rauchwerger
patent: 3771548 (1973-11-01), Rauchwerger
patent: 3864974 (1975-02-01), Rauchwerger
patent: 3879644 (1975-04-01), Maltby
patent: 3958159 (1976-05-01), Rauchwerger
patent: 4025846 (1977-05-01), Franz et al.
patent: 4064753 (1977-12-01), Sun et al.
patent: 4347741 (1982-09-01), Geiger
patent: 4383445 (1983-05-01), Siegel et al.
patent: 4417472 (1983-11-01), Tward
patent: 4417473 (1983-11-01), Tward et al.
patent: 4449405 (1984-05-01), Franz et al.
patent: 4483463 (1984-11-01), Buschmann
patent: 4499766 (1985-02-01), Fathauer et al.
patent: 4515015 (1985-05-01), Kuhlman
patent: 4683418 (1987-07-01), Wagner et al.
patent: 4757252 (1988-07-01), Maltby et al.
patent: 4903530 (1990-02-01), Hull
patent: 5042299 (1991-08-01), Wells
patent: 5083460 (1992-01-01), Kumada et al.
patent: 5337353 (1994-08-01), Boie et al.
Brown Glenn W.
Flowline Inc.
Wieder Kenneth A.
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