HH5200i Conductivity Electrode| Two-Electrode Graphite Digital Conductivity Sensor

The HH5200i is a digital two-electrode conductivity sensor with its signal conditioning, temperature compensation, and communication electronics integrated into the sensor body. It connects directly to a compatible PLC, controller, gateway, data logger, or automation platform using Modbus RTU over RS485.

Its graphite measuring electrodes provide a mechanically simple conductivity-measurement platform with compatibility across many water and industrial applications. The sensor measures conductivity up to 70 mS/cm, equivalent to 70,000 μS/cm, covering many surface-water, wastewater, aquaculture, seawater, and process-water conditions.

Unlike a conventional analog conductivity electrode, the HH5200i processes the measurement internally and supplies digital data without requiring a separate conductivity transmitter. A receiving controller, display, PLC, or gateway is still required to power the sensor, read its Modbus registers, display the result, or use the data for process control.

An integrated NTC 22K element provides temperature data. The standard configuration compensates conductivity to 25 °C using a linear coefficient of 2%/°C. This default may be suitable for some general aqueous solutions, but the correct coefficient depends on the actual ionic composition and concentration.

The sensor uses a POM housing with a G3/4 process connection and integrated cable. Pipeline and immersion versions are available, together with a low-power configuration for energy-constrained monitoring systems.

Key benefits

• Integrated digital electronics: Conductivity measurement, temperature compensation, and communication are handled inside the sensor.
• Direct control-system integration: Modbus RTU allows connection to compatible PLCs, controllers, gateways, and monitoring platforms.
• Graphite measuring element: Provides a corrosion-resistant electrode material for many compatible aqueous processes.
• Broad measurement coverage: One sensor configuration measures up to 70 mS/cm without field selection between multiple replaceable cell constants.
• Wide power input: Operates from a 6–30 VDC supply.
• Flexible installation: Available for compatible pipeline and immersion assemblies.
• Long-distance communication: Cable lengths up to 100 metres are available when power and RS485 network requirements are satisfied.

Configuration options

• Low-power version: Available for battery-powered or energy-constrained systems.
• Installation configuration: Pipeline and immersion versions are available.
• Extended cable: Cable lengths up to 100 metres, subject to supply-voltage drop and RS485 network design.
• Communication settings: Device address, baud rate, parity, register map, and byte order should be matched to the receiving system.
• Process adapter: Confirm the exact G3/4 thread form, seal, and required immersion depth before ordering.

Measurement and installation notes

Two-electrode conductivity sensors can be affected by electrode polarization at higher conductivity. Confirm accuracy and linearity near the upper portion of the 70 mS/cm range under representative process conditions.

The minimum usable conductivity and resolution have not been provided. Although surface water is listed as an application, the sensor should not be positioned for pure or very low-conductivity water until its low-end performance is verified.

The fixed 2%/°C compensation coefficient is not universal. Seawater, concentrated salts, acids, alkalis, nutrient solutions, and mixed wastewater can have different or nonlinear temperature behaviour. Where necessary, use raw conductivity and temperature data with a validated application-specific compensation model, if supported by the Modbus protocol.

Deposits, biofilm, oil, scale, and suspended solids can change the effective measuring surface and cause drift or slow response. Install the sensor in a representative flowing location with access for inspection and cleaning.

Graphite and POM offer compatibility with many aqueous media, but the complete construction—including seals, cable jacket, junctions, and process fitting—must be checked against the actual chemicals, concentrations, temperature, pressure, and cleaning agents.

For long RS485 networks, use suitable twisted-pair cabling, daisy-chain topology, unique device addresses, correct polarity, and appropriate termination and biasing.

Classification

Product Type

• Industrial Sensors

Parameter

• Conductivity
• Temperature

Connectivity

• Digital
• RS485
• Modbus RTU

Application

• Surface Water Monitoring
• Industrial Wastewater Treatment
• Seawater & Brackish Water
• Aquaculture
• Agricultural & Fertigation Water
• Industrial Process Water
• OEM Monitoring & Automation Systems
• Remote Water-Quality Monitoring