The Omron 61F-GP-N AC110 is a High/Low Level controller from the 61F series, designed for conductive liquid level sensing in tanks, sumps, and process vessels. It operates on a 110VAC supply and provides SPDT relay output (2 Form C) rated at 3A @ 250VAC — enough to drive a small pump or alarm directly. Sensitivity is adjustable from 0 to 4 kOhm, which covers most tap water and light chemical solutions; the 1 km max distance between controller and electrode lets you place the unit in a central panel while the probes sit at the tank.
The 0–4 kOhm sensitivity range is the key selection parameter: it sets the conductivity threshold at which the relay picks up. For low-conductivity fluids (deionized water, some condensates), you may need a lower range than this controller offers — the 61F series also includes models with a 0–100 kOhm range for those cases. The 110VAC supply is standard for industrial panels in many regions, but if your control voltage is 24VAC/DC or 220VAC, this unit will not work without a transformer. The socketable 11-pin octal base (standard 8- or 11-pin octal relay footprint) makes replacement quick — pull the old unit, plug in the new one — but verify that your existing socket is wired for the 61F pinout, which differs from a plain octal relay.
Integration Notes
Termination is plug-in; no tools needed for replacement. The relay output is SPDT (2 Form C), meaning you get one normally-open and one normally-closed contact per pole — useful for both pump control and alarm indication on the same unit.