The Omron 61F-G4NL AC110/220 2KM is a High/Low Level controller from the 61F series, designed for liquid level detection and control in industrial tanks, sumps, and process vessels. It operates on a dual-range supply of 110/220VAC and drives relay outputs with SPDT contact configurations — two Form C and three Form C — rated at 3A at 200VAC. The unit accepts a two-wire electrode probe and can be mounted up to 2 km from the sensor, making it suitable for remote tank farms or large-site level monitoring.
The 2 km control-to-sensor distance is the maximum cable run between the controller and the electrode probe — not the tank depth. For a 50 m tank farm run, you have ample headroom; for a 2.5 km pipeline sump, this part won't reach. The sensitivity adjustment range of 0 to 1.8 kOhm lets you tune the detection threshold for different liquid conductivities — set low for distilled water or high-conductivity process fluids, set high for aggressive chemicals or foaming media where false triggering is a concern. The relay output with SPDT contacts provides both normally-open and normally-closed switching per level point, so you can wire for pump-up (fill) or pump-down (drain) logic without external inverters. The 3A at 200VAC contact rating is sufficient for pilot-duty solenoid valves, alarm annunciators, or small contactor coils — but not for direct motor starting above fractional horsepower. DIN rail mounting means it clips onto standard 35 mm top-hat rail inside a control panel.
High/Low Level controllers like this one are deployed in water and wastewater treatment, chemical batching, coolant sump management, and food-and-beverage tank level control. The idling prevention feature stops a pump from running dry when the low-level probe breaks contact — a common failure mode that burns out pump seals and motors. The level indication output can drive a panel lamp or PLC input for remote status.