Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-02-22
1999-01-05
Hofsass, Jeffery
Communications: electrical
Condition responsive indicating system
Specific condition
340612, 340620, 73304C, 73304R, 331 64, 331 65, 324660, 324674, G08B 2100
Patent
active
058567836
ABSTRACT:
A pump control system which can distinguish between water and oil so that a pump can be controlled to pump water and deactivated before oil is pumped. Sensing is accomplished by a pair of capacitive sensors, one located above the other in a vessel in which water accumulates. A dual mode frequency oscillator is associated with each sensor. Each sensor reacts to the dielectric constant of the liquid at the sensor by changing its capacitance, to thus detect the presence of a conductive substance, such as a liquid, to cause the sensor's oscillator to switch its mode of oscillation. The dual mode oscillator of each sensor selectively generates a control signal having two different duty cycles. As the dielectric constant of the liquid medium is sensed, a logic circuit interposed between the sensors allows the output of each sensor to be turned off when only the lower sensor is in water. The circuit turns on the pump only when both sensors are in water and the pump remains on until both sensors are out of water. An adjustable deadband is provided, thereby avoiding having the pump turning on and off with a slight water level change. Each sensor detects the difference between dielectric constants of air and of oil, in relation to that of water. As a result, the pump control system differentiates between water and oil and activates the system to pump water while deactivating the system before oil on the water surface is pumped.
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Hofsass Jeffery
Lefkowitz Edward
Raptor, Inc.
Waters William Patrick
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