Why Choose the Finder 72.01.8.240.5002 Liquid Level Control Relay?
The Finder 72.01.8.240.5002 is a versatile liquid level monitoring and control relay designed for automatic filling, emptying and level supervision of tanks containing electrically conductive liquids. Part of the Finder 72 Series monitoring relay range, it provides reliable liquid level detection for industrial automation, water management, pumping installations and process control systems.
Featuring an adjustable sensitivity range of 5–450 kΩ, this specialised level control relay can detect conductive liquids with relatively low electrical conductivity. Its 230–240 V AC supply, selectable filling or emptying functions and 16 A changeover output contact make it suitable for a wide range of liquid level control applications. The relay can operate with two electrodes for single-level monitoring or three electrodes for minimum and maximum level control.
The Finder 72.01.8.240.5002 also features gold-plated silver nickel (AgNi + Au) output contacts, enabling dependable switching of low-level control signals down to 5 V and 1 mA. This makes it particularly useful for integration with electronic control circuits and the Finder 72.42 pump priority change relay. Its compact 35 mm DIN rail housing, adjustable sensitivity and selectable delay provide a practical solution for industrial tank monitoring and automatic pump control.
Key Advantages
- Automatic filling and emptying control for tanks containing conductive liquids.
- Adjustable 5–450 kΩ sensitivity range for different liquid conductivity levels.
- Low-conductivity liquid detection suitable for applications down to approximately 2 µS conductivity under specified conditions.
- 230–240 V AC operating supply for industrial electrical control installations.
- 16 A changeover output contact for switching suitably rated control and electrical loads.
- Gold-plated AgNi + Au contacts support reliable low-current signal switching.
- Minimum switching capability of 5 V at 1 mA for sensitive electronic control applications.
- Selectable 0.5 s or 7 s delay helps prevent unwanted switching caused by liquid movement.
- Two-electrode or three-electrode operation for single-level or minimum/maximum level monitoring.
- 35 mm DIN rail mounting simplifies installation in electrical control cabinets.
- IP20 protection rating for use within appropriately protected electrical enclosures.
- Suitable for integration with Finder 72.42 pump alternation and priority control relays.
Key Features
- Finder 72 Series liquid level monitoring relay.
- Type 72.01 adjustable sensitivity level controller.
- Conductive liquid level detection using external electrodes.
- 5–450 kΩ adjustable sensing sensitivity.
- 230–240 V AC supply voltage at 50/60 Hz.
- Single changeover (SPDT / 1 CO) output contact.
- 16 A rated output current.
- AgNi + Au gold-plated contact material.
- 5 V / 1 mA minimum switching capability.
- Filling or emptying operating modes.
- Selectable 0.5 s or 7 s delay.
- Two-electrode or three-electrode sensing arrangements.
- 4 V AC electrode sensing voltage.
- 0.2 mA electrode sensing current.
- 35 mm modular DIN rail housing.
- IP20 protection rating.
- Operating temperature range of −20 to +60 °C.
- Designed for integration into industrial pumping and tank level control systems.
Technical Specifications
- Manufacturer: Finder
- Series: 72 Series Monitoring Relays
- Model: 72.01.8.240.5002
- Product type: Liquid level control relay
- Relay type: 72.01
- Monitoring principle: Conductive liquid level detection
- Supply voltage: 230–240 V AC
- Supply frequency: 50/60 Hz
- Rated supply consumption: 2.5 VA
- Output configuration: 1 changeover contact (1 CO / SPDT)
- Rated output current: 16 A
- Rated contact voltage: 250 V AC
- Contact material: Silver nickel with gold plating (AgNi + Au)
- Minimum switching voltage: 5 V
- Minimum switching current: 1 mA
- Sensitivity adjustment range: 5–450 kΩ
- Low-conductivity detection capability: Down to approximately 2 µS
- Operating functions: Filling / emptying
- Selectable delay: 0.5 s or 7 s
- Electrode sensing voltage: 4 V AC
- Electrode sensing current: 0.2 mA
- Electrode inputs: 3
- Single-level control: Two-electrode arrangement
- Minimum/maximum level control: Three-electrode arrangement
- Protection rating: IP20
- Mounting type: 35 mm DIN rail
- Connection type: Screw terminals
- Housing width: 35 mm
- Housing height: 84 mm
- Housing depth: 54.6 mm
- Operating temperature: −20 to +60 °C
- Insulation between supply, contacts and electrodes: Reinforced insulation
- Impulse withstand voltage: 6 kV
- Compatible control accessory: Finder 72.42 priority change relay
- EAN: 8012823364186
Reliable Liquid Level Monitoring and Automatic Pump Control
The Finder 72.01.8.240.5002 monitors liquid levels by measuring electrical conductivity between sensing electrodes installed inside a tank or reservoir. When the liquid reaches or falls below the selected electrode positions, the relay responds according to its configured filling or emptying function. This allows pumps, valves and control circuits to be operated automatically without requiring continuous manual supervision.
The relay supports two-electrode and three-electrode sensing arrangements. A two-electrode installation can monitor a single liquid level, while a three-electrode configuration provides minimum and maximum level control. In suitable conductive metal tanks, the tank itself may serve as the common electrode, simplifying the sensing arrangement.
Its adjustable 5–450 kΩ sensitivity is particularly valuable when monitoring liquids with varying conductivity. The extended sensitivity range enables the relay to detect liquids with relatively low conductivity, making it more flexible than standard fixed-sensitivity level controllers. Correct sensitivity adjustment depends on the liquid characteristics, electrode installation and electrical conditions.
The filling mode can be used to start a pump when the liquid falls to a minimum level and stop it when the required maximum level is reached. In emptying mode, the relay can operate a pump to remove liquid from a tank or sump when the level rises, stopping the pump once the lower level is reached. These functions help automate water management and reduce unnecessary pump operation.
The selectable 0.5 s or 7 s delay helps prevent unwanted relay switching caused by waves, splashing or temporary changes in liquid contact with the electrodes. Selecting the appropriate delay can improve the stability of pump control systems and reduce unnecessary switching cycles.
A distinguishing feature of the 72.01.8.240.5002 is its gold-plated AgNi + Au changeover contact. Unlike standard contacts intended primarily for larger electrical loads, this version supports reliable switching of low-level signals down to 5 V and 1 mA. This makes it especially suitable for electronic control inputs and applications involving the Finder 72.42 pump priority change relay, where low-current control signals are used to coordinate pump operation.
With its 16 A changeover output, compact DIN rail design and adjustable sensing characteristics, the Finder 72.01.8.240.5002 can form part of a dependable liquid level automation system. Where pumps or other loads exceed the relay's switching capability, a suitably rated contactor or motor starter should be used. The relay is intended for conductive liquids and is not suitable for direct detection of non-conductive liquids such as oils.
Typical Applications
- Automatic water tank filling and emptying systems.
- Industrial liquid level monitoring and control.
- Water treatment and filtration installations.
- Wastewater pumping and sump management systems.
- Reservoir minimum and maximum level control.
- Low-conductivity liquid monitoring in suitable industrial processes.
- Industrial pump start and stop control circuits.
- Tank overflow prevention and low-level alarm systems.
- Pump alternation systems using Finder 72.42 priority change relays.
- Industrial process tanks and storage vessels.
- Building services and water distribution control panels.
- PLC-connected liquid level monitoring systems.
- OEM pumping equipment and electrical panel manufacturing.
