The Omron 61F-G1NR AC110/220 is a High/Low level controller from the 61F series, designed for liquid-level monitoring in tanks, reservoirs, and process vessels. It operates on a 110/220VAC supply and uses a two-wire or three-probe sensing method with a sensitivity range of 0 to 1.1kOhm — adjustable to match the conductivity of the liquid. The relay output (2x SPDT Form C) is rated 3A at 200VAC, enough to drive a pump contactor or alarm directly. Mounts on standard DIN rail (snap-on) with screw terminals for field wiring. The control-to-sensor distance can reach 800m, so the controller can sit in a central panel while the probes are out at the tank. Built-in features include Alarm Low contact and idling prevention — the latter keeps the pump from cycling on foam or turbulence.
The 0–1.1kOhm sensitivity covers most conductive liquids — water with typical tap conductivity (500–800 µS/cm) is well within range, but deionized water or low-conductivity hydrocarbons may need a different controller. The 800m cable distance is the maximum between controller and probe; voltage drop over that length at the probe's sensing current is negligible with the recommended cable gauge. The 3A contact rating at 200VAC is sufficient for direct control of a small pump contactor (e.g., up to 0.75 kW) or pilot relay. For larger loads, interpose a contactor. The SPDT (Form C) per channel gives both fill and empty logic without an external inverter.
DIN-rail snap-on mounting with screw terminals means a 5-minute swap on a live panel if you pre-wire a removable terminal block.