What it is and what it does
The Omron 61F-GP-N8L-4KM AC240 is a High/Low Level controller from the 61F series, built for tank-level monitoring and control. It runs on a 240VAC supply and switches a SPDT (2 Form C) relay rated at 3A @ 250VAC — enough to kick a pump contactor or a solenoid valve directly. The sensitivity range of 0 ~ 0.5kOhm means it detects conductive liquids (water, mild chemicals) through a pair of probes; the 4km max distance between the controller and the sensor head makes it a good fit for remote tank farms or large reservoirs where the panel sits a long way from the tank. It mounts into an 8-pin octal socket (plug-in termination), so swapping a failed unit takes seconds — no re-wiring the panel. The operating range of -10°C to 55°C covers most indoor control rooms and sheltered outdoor cabinets.