Used for tank level control via float switch when connected with a long cable to the pump panel. The operating distance is approximately 1,000m, depending on the type and cross-section of the cable used. It is connected with a ball-type float switch.

The relay is energized when the tank level is low and the float switch contact is short-circuited. Conversely, the relay is de-energized when the tank is full and the float switch contact is open.