ABB Conductivity Analyzer Application Guide

ABB Conductivity Analyzer: High precision Industrial Water Quality Online Monitoring and Intelligent Analysis Solution

Real time and accurate conductivity monitoring is the key to ensuring production process safety, improving product quality, and controlling costs in industrial fields such as power, chemical, pharmaceutical, and microelectronics that require extremely high water purity. As a global leader in process automation, ABB's conductivity analyzer integrates advanced sensing technology, intelligent algorithms, and robust industrial design, providing a reliable and powerful tool for continuous monitoring and control of solution conductivity. This article is based on ABB's official technical manual, providing a comprehensive analysis of the design principles, core functions, configuration methods, and practical applications of the analyzer.

Instrument Overview and Design Concept

The ABB conductivity analyzer is designed for continuous online monitoring and control, offering two versions for wall/pipeline installation and disk installation, and supporting single or dual sensor input modes. Each sensor channel is equipped with an independent temperature input (supporting Pt100 or Pt1000 platinum resistors) for achieving high-precision temperature compensation.

The core operation of the instrument is completed through five tactile membrane buttons on the front panel, combined with a dual layer display interface: the upper layer consists of two rows of 4 and a half digit digital tubes, which are used to display measurement values, alarm setpoints, and units; The lower layer is a 16 character dot matrix display screen that provides programming and status information. All programming functions are protected by a five digit secure password to prevent unauthorized tampering, ensuring the stability and security of process control.

Core functions and advanced applications

1. Automatic Temperature Compensation (ATC): From Principle to Practice

The conductivity of a solution is significantly affected by temperature. This analyzer provides multiple advanced temperature compensation modes, far beyond simple linear compensation:

No compensation: Suitable for situations where raw measurement values are required, such as monitoring of water for injection (WFI) and purified water in accordance with the United States Pharmacopeia (USP).

Linear compensation: suitable for monitoring non-standard solutions or solutions of unknown purity with known temperature coefficient (α).

Pre set curve compensation: For specific impurity types in pure water systems, multiple pre set compensation curves are provided, including UPW (pure water), HCl (trace acid), NaOH (trace alkali), NaCl (trace salt), and NH3 (trace ammonia). For example, in the water treated with ammonia in the boiler, selecting the NH3 compensation curve can more accurately reflect the true changes in impurity concentration.

Its advanced compensation algorithm, especially for ultrapure water (UPW), not only considers the temperature effect of impurity ions (usually α ≈ 0.02/° C), but also separates and compensates for the main effects of H ⁺ and OH ⁻ ions generated by hydrolysis ions when approaching the state of ultrapure water. The compensated readings are uniformly converted to the international standard reference temperature of 25 ° C, ensuring comparability and accuracy of the data under different temperature conditions.

2. Dual sensor input and differential conductivity application

The dual input model greatly expands the application range of the instrument, and by comparing the readings of two sensors, various calculations can be performed:

Ratio (A/B) and difference (A-B): used to monitor the performance of ion exchange columns, desalination rate of reverse osmosis systems, etc.

Transmittance (% Passage) and Rejection (% Rejection): Directly calculate the percentage of conductivity passing through or being rejected in the processing unit, which intuitively reflects the processing efficiency.

Inferred pH: This is an advanced feature of the analyzer. Given the presence of only a single regulator (such as ammonia or sodium hydroxide) in a known sample, the pH value of the sample can be calculated by measuring the difference between the specific conductivity before and after passing through the cation exchange column, known as the "inferred pH". This function is widely used in the monitoring of boiler water chemical treatment (such as ammonia and hydrazine addition). The instrument can be programmed to set a conductivity alarm limit for cations (0.060-1.000 μ S/cm). If this limit is exceeded or the conductivity before cations exceeds 10 μ S/cm, an alarm will be triggered, indicating the presence of other impurities and verifying the validity of the inferred pH value.

3. Flexible analog output and alarm configuration

The analyzer provides isolated analog current output (0/4-20mA), which can be flexibly allocated to any measured variable (conductivity or temperature). The output function supports linear, bilinear, and logarithmic outputs of 2 or 3 orders of magnitude, making it very suitable for situations with a wide range of conductivity changes (such as from ultrapure water to concentrated saltwater).

The alarm function is powerful, and each alarm can be independently set to fail safe or non fail safe mode, equipped with adjustable delay time and lag interval, effectively preventing false alarms caused by process noise or instantaneous fluctuations.

Key points for installation, calibration, and maintenance

1. Installation specifications and EMC considerations

Correct installation is the foundation for ensuring measurement accuracy and long-term stability.

Location selection: It should be installed in a location that is free from excessive vibration, avoids harmful vapors or droplets, and is easy to observe. The cable length between the sensor and analyzer needs to be limited according to the conductivity cell constant (K) (≤ 50m when K<0.1, ≤ 100m when K ≥ 0.1).

Wiring and grounding: Protective grounding (PE) is crucial and must be reliably connected to the grounding bolts of the enclosure to ensure personal safety, suppress radio frequency interference (RFI), and ensure the normal operation of the power filter. The metal braided layer of the conductivity pool cable is prohibited from grounding, and it should be cut short to the insulation layer at the end of the conductivity pool.

Wiring isolation: Signal lines (conductivity pool, analog output) should be laid separately from power lines (power supply, relay), preferably in grounded metal tubes to minimize electromagnetic interference.

Relay protection: If the relay is used to switch loads, arc extinguishing elements (RC absorbers for AC and freewheeling diodes for DC) must be connected at both ends of the contacts to prevent contact erosion and RFI interference with the normal operation of the analyzer.

2. Calibration and fault diagnosis

The analyzer undergoes precise calibration before leaving the factory, using high stability components and an analog-to-digital conversion chip with self compensation function, so regular calibration is usually not required. Calibration is mainly carried out when replacing the input board or when there is suspicion that the calibration data has been tampered with.

Calibration method: Simulate the resistance of the conductivity cell and temperature sensor by connecting them to a precision resistance box. Follow the "Factory Settings" menu to complete the calibration of the sensor zero point, span, and internal reference voltage in sequence.

Troubleshooting: The instrument provides clear error information (such as "A: FAULTRA Pt100"). If there is no response during measurement, first check if the conductivity cell is clean and if the parameter settings are correct. It is possible to quickly determine whether the fault point is located in the analyzer, cable, or conductivity cell itself by disconnecting the sensor and directly connecting it to the analog input of the resistance box. The method for checking temperature input is similar.

Summary of Technical Specifications

Measurement range: 0-0.5 to 0-10000 μ S/cm (depending on the conductivity cell constant K value).

Measurement unit: Supports μ S/cm, mS/cm, M Ω· cm, and TDS (conversion coefficient input required).

Accuracy: better than ± 1% of the reading.

Temperature compensation range: -10 to 150 ° C.

Display: Dual row backlit LCD digital tube and dot matrix character display.

Analog output: standard 2 channels, optional extension to 4 channels; 0/4-20mA， Isolated output with an accuracy of ± 0.25% FSD.

Environmental rating: Complies with EN 61326 (industrial environment) EMC standards, with a protection level typically NEMA 4X/IP66.

Power supply: usually AC or DC low voltage power supply.