The Omron 61F-GPN-BC 24VDC is a conductive level controller from the 61F series, wired as a High/Low Level detector. It runs on 24VDC and switches a relay rated 5A at 240VAC — enough to drive a small pump contactor or alarm directly. The adjustable sensitivity (0 to 100kΩ) lets you tune it for different water conductivities or process fluids; the 100m max distance between controller and sensor probes means the electronics can sit in a dry panel while the probes live at the tank.
Mounts via an 11-pin octal socket (sold separately). The plug-in termination style means a failed unit swaps in seconds without rewiring — critical-spare logic: keep one in the cabinet.