Liquid Level Controls (LLC) are designed to detect and control levels of liquids which are electrically conductive. These controls sense the resistance value between the probe(s) and the common point. The conductive liquid completes the electrical path between the probe(s) and the common point. The LLCs then compare this value with a fixed setpoint value or as determined by the adjustable potentiometer. The output of these LLC’s can be used to turn on and off pumps, solenoids, or valves to lower, raise, or maintain the liquid level in a containment tank.
Applications:
Single-Probe Level Control
Liquid Resistance Chart
A low cost, open board, single probe LLC1 series, or 8-pin plug-in LLC4 series, with the ‘A’ drain logic, is being used as an AC/R condensate level control. When the conductive condensate (18K typical) touches the probe, the resistance between the probe and common decreases to a value below the selected trip point. The output remains de-energized until a fixed time delay is completed. Then the LLC’s output energizes causing the pump to run. As the reservoir begins to drain, the condensate level drops. Contact between the probe and the condensate is broken causing the resistance to increase to a value above the trip point. Then the output of the LLC transfers and the pump is de-energized; ending the pump down cycle.
NOTE: Conductive level sensing should not be used with distilled water. Its measured resistance is >450K.
FOR MORE APPLICATIONS Please Download the SSAC Application Sheet.
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