Liquid Level Control Relay RD-LC1

The RELETEK RD-LC1 Liquid Level Control Relay is a microcontroller-based liquid level monitoring and control device designed to automatically manage the level of conductive liquids in tanks, reservoirs, wells, and similar systems. By using conductive electrodes as level sensors, the relay detects changes in liquid level and switches its output contact accordingly, making it suitable for automatic filling or draining control in electrical and industrial automation systems.

The RD-LC1 supports 2-electrode and 3-electrode operating modes, allowing it to be configured for different liquid-level control arrangements. In a typical two-level application, electrodes can be positioned at minimum and maximum levels to control a pump or contactor according to the liquid level. The relay can therefore be integrated into systems where maintaining a defined liquid level is required, such as water tanks, pumping systems, industrial reservoirs, and agricultural irrigation installations.

A key feature of the RD-LC1 is its adjustable sensitivity from 5kΩ to 100kΩ. This adjustment allows the controller to respond to different electrical conductivity conditions of the monitored liquid. The unit also provides a 2-second trip delay, helping reduce unwanted switching caused by short-duration changes or unstable liquid contact with the electrodes.

The relay is powered through terminals A1-A2 and supports 220V AC or 380V AC at 50/60Hz, with a power consumption of less than 1W. Its output consists of one changeover contact (1 C/O) rated at 8A/250V AC-1, allowing it to control compatible loads directly or operate a contactor when higher-current pumps or equipment need to be switched.

For installation and troubleshooting, the RD-LC1 includes separate green and red LED indicators for supply and output status. The controller uses a compact 2-module DIN-rail housing and is designed for TH-35 rail mounting according to EN 60715, making it suitable for electrical distribution boards and automation control panels.

The RELETEK RD-LC1 is therefore a practical solution for automatic liquid-level control where conductive-liquid sensing and relay-based switching are required. For loads exceeding the relay's 8A AC-1 rating, a suitable contactor should be used rather than connecting the load directly to the relay output.

Features

• Microcontroller-based liquid level controller

• Adjustable sensitivity from 5kΩ to 100kΩ

• Supports 2 or 3 electrodes

• 220V / 380V AC supply

• 2-second trip delay

• One changeover relay output

• 8A / 250V AC-1 contact rating

• Green power and red output LED indicators

• Compact 2-module DIN-rail design

• TH-35 rail mounting

Specifications

Specifications are based primarily on the manufacturer's RELETEK documentation.

Applications

• Water tank level control

• Well and reservoir monitoring

• Automatic pump control

• Tank filling systems

• Tank drainage systems

• Industrial liquid-level control

• Agricultural irrigation systems

• Water treatment and pumping installations

• Electrical automation panels

• Contactor control for liquid pumping equipment