The Omron 61F-I AC110/220 is a conductive-type level controller from the 61F series, built to sense high or low liquid levels and switch a relay accordingly. It runs on a dual-range 110/220VAC supply, so it slots into panels wired for either voltage without a separate transformer tap. The relay output is SPDT (2 Form C), rated at 5A at 220VAC — enough to kick a small pump contactor or alarm beacon directly. Sensitivity is adjustable from 0 to 4kOhm, which covers most conductive liquids (water, mild acids, coolants) but lets you dial out false triggers from foamy or slightly scaling media. Control distance from the sensor head to the controller can run up to 1km, so the 61F-I can sit in a central MCC while the probes live at a remote tank or sump.
Chassis-mount form factor — no DIN rail clip here. Plan for a screw-down footprint on a backplate or inside a small enclosure. The dual-voltage supply (110/220VAC) means the same unit works on a 120V control transformer or a 208/240V line. No jumper to move — it auto-ranges internally. Just watch that the neutral is bonded per local code; the controller expects a referenced AC supply.
Where It Runs
You'll find these in sump pump panels, cooling tower basins, condensate tanks, and coolant reservoirs on machine tools. The conductive sensing principle needs the liquid to carry some conductivity — distilled water or deionized water won't trigger it, but tap water, well water, and most process fluids will. Not rated for direct outdoor exposure or washdown zones — keep it dry.