Point level switch

Details Point level switch Point level switch

1991-01-03

1992-06-16

Cuchlinski, Jr., William A.

Measuring and testing

Liquid level or depth gauge

Immersible electrode type

324663, 364575, G01F 2326

Patent

active

051216329

ABSTRACT:
A point level sensor senses capacitance of a material in a vessel to determine level. The capacitance is input to a comparator which is part of an oscillator circuit developing a square wave signal having a period corresponding to capacitance. A microprocessor includes an internal counter which determines the period of four pulses to determine an average period. The microprocessor drives relay circuits providing discrete outputs according to specific precalibrated levels to be sensed. The point sensor includes a self-test mode which operates once per second to test for shorting of the probe, expected frequency response and an open probe.

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