What it is and what it does
The Omron 61F-GL AC100/200 2KM is a conductive level controller that detects high or low liquid levels using probes. It's built for bulk tanks, sumps, or any wet well where you need a relay to kick a pump or valve when the level hits a set point. It runs on 100/200VAC supply and outputs through a SPDT relay (2 Form C) rated 5A at 220VAC — enough to directly switch a small pump contactor without an interposing relay. Sensitivity is adjustable from 0 to 1.8 kOhm, which means it works with plain stainless rods in clean water or slightly conductive process fluids. The 2 km max distance between controller and sensor head gives you flexibility to mount the electronics away from the tank.
Mounting and wiring in the field
Chassis mount with screw terminals — no DIN rail, so you'll need to drill the panel or use a separate DIN adapter plate if your enclosure is set up for rail. The screw terminals accept standard ring or fork lugs; strip length around 8 mm. Operating range is -10°C to 55°C, fine for most indoor control panels. If this lives in an unheated pump house in a northern winter, keep it above freezing.
What the ratings mean for your BOM
The 5A @ 220VAC contact rating is resistive — if you're switching an inductive motor load, derate or add a contactor. The SPDT (2 Form C) gives one N.O. and one N.C. set of contacts, so you can wire both high-level alarm and low-level pump start from the same unit. Sensitivity range of 0 to 1.8 kOhm covers the conductivity of most water-based liquids. For oils or non-conductive fluids, you'd need a different sensing method (capacitive or ultrasonic).