Overview of ABB 266GST

The ABB 266GST is a gauge pressure transmitter intended for demanding industrial pressure measurement applications. The transmitter measures pressure relative to atmospheric pressure and converts the measured process variable into an electrical or digital communication signal for use by a process control system.

The 266GST can be applied to different process media, including liquids, gases, and steam. In addition to pressure measurement, ABB specifies the transmitter for liquid level measurement in open tanks. This makes the device suitable for process plants where pressure and level measurement are integrated into automation and instrumentation systems.

The transmitter is available in different sensor ranges, process connections, housing configurations, communication protocols, and certification options. Therefore, the complete ordering code should be checked when identifying a specific 266GST configuration.

Product Identification

Gauge Pressure Measurement

The primary function of the ABB 266GST is gauge pressure measurement. Gauge pressure represents the difference between process pressure and the surrounding atmospheric pressure. This measurement method is commonly used in industrial systems where the pressure inside a process vessel, pipeline, or equipment section needs to be monitored relative to ambient conditions.

The transmitter receives pressure through its process connection and uses its pressure sensing element to determine the process value. The internal electronics process the sensor signal and provide the measured pressure through the selected output and communication interface.

Depending on the selected configuration, the 266GST can be integrated into conventional analog control systems or digital process automation networks. The appropriate communication option should be selected according to the control architecture and instrumentation requirements of the installation.

Accuracy and Measuring Range

ABB specifies a base accuracy of ±0.04% for the 266GST, with an optional accuracy of ±0.025% for configurations equipped with the corresponding accuracy option. This performance makes the transmitter suitable for applications where pressure measurement accuracy is an important part of process control.

The 266GST family covers a wide range of sensor span limits. Depending on the selected sensor configuration, the span limits can range from low-pressure measurement starting at 0.2 kPa to high-pressure measurement up to 60000 kPa. Individual configurations also have different overpressure limits.

The exact measuring range is determined by the complete transmitter ordering code and the selected sensor option. When replacing an existing transmitter, the calibrated range shown on the transmitter identification information should therefore be compared with the required process range.

Communication Options

The ABB 266GST is available with multiple communication technologies. Depending on the selected version, the transmitter can use a 4 to 20 mA output with HART communication, PROFIBUS PA, or FOUNDATION Fieldbus.

The 4 to 20 mA and HART configuration allows the transmitter to be integrated into conventional process instrumentation systems while providing digital communication for configuration, diagnostics, and measurement information. PROFIBUS PA and FOUNDATION Fieldbus configurations provide alternatives for process plants using digital fieldbus architectures.

Communication selection is configuration-dependent. A replacement transmitter should use a compatible communication protocol and hardware configuration to match the existing control system.

Local Display and Through The Glass Technology

The 266GST can be equipped with an optional local display. ABB also provides Through The Glass, or TTG, technology on compatible configurations. This technology allows selected transmitter functions to be configured through the front glass without removing the windowed cover.

Through The Glass operation can simplify field configuration and inspection because the operator does not need to open the transmitter housing for routine local interaction. This feature can be particularly useful in process environments where minimizing enclosure access is desirable.

The exact display and local operation features depend on the transmitter configuration. When ordering or replacing a 266GST, the display and operating options should therefore be checked against the original device requirements.

Typical Applications

ABB 266GST can be used in a wide range of process industries. Typical applications include pressure measurement on process pipelines, pressure monitoring on vessels, steam pressure measurement, gas pressure measurement, and liquid pressure measurement.

The transmitter can also be used for level measurement in open tanks. In this application, the pressure generated by the liquid column is related to the liquid level, allowing the transmitter to provide a continuous measurement signal to the process control system.

Other applications can include chemical processing, energy production, water and wastewater treatment, oil and gas facilities, pulp and paper processes, and general industrial process automation. The final application suitability depends on the process medium, pressure range, temperature, materials, connection type, and required certifications.

Process Connection and Materials

The 266GST is available with different process connection and wetted-part configurations. Selection of suitable materials is important because the pressure transmitter is directly exposed to the process medium through its pressure sensing system.

For corrosive or chemically aggressive media, the wetted materials should be selected according to the characteristics of the process fluid. ABB documentation provides different material and process connection options within the 266GST ordering structure.

Before installation, the process connection, sealing arrangement, pressure rating, and material compatibility should be checked. The transmitter should be installed using a configuration appropriate for the actual process conditions rather than relying only on the general 266GST model designation.

Installation Considerations

Correct installation is important for obtaining stable pressure measurement. The transmitter should be mounted according to the applicable ABB installation instructions and the requirements of the process connection.

Process piping should be arranged so that the transmitter is not exposed to unnecessary mechanical stress. The installation should also consider process temperature, ambient temperature, vibration, pressure pulsation, and the properties of the measured medium.

For liquid applications, the installation arrangement should minimize the possibility of gas pockets affecting measurement. For gas applications, the arrangement should avoid unwanted liquid accumulation in the sensing connection. Steam applications may require suitable impulse piping and condensate arrangements according to the process installation design.

Configuration and Calibration

ABB 266GST transmitters can be configured according to the selected communication and display options. Typical configurable parameters include the measuring range, engineering unit, output scaling, damping, alarm settings, and identification information.

ABB documentation states that transmitters are calibrated according to the specified measuring range. The calibrated range and measuring point information can be provided on the transmitter identification plate. If a specific range has not been specified, the transmitter may use a standard configuration according to the selected communication version.

When commissioning a 266GST, the configured measuring range should be checked against the process requirements. Incorrect range settings can result in an unsuitable output scaling even when the pressure sensor itself is functioning correctly.

Safety and Certification

The ABB 266GST has configurations intended for safety-related applications. ABB states that the transmitter is certified by TÜV NORD according to IEC 61508 and can meet SIL2 requirements in a single-transmitter 1oo1 configuration and SIL3 requirements in a redundant 1oo2 configuration.

Additional hazardous-area certifications and process-specific options are available depending on the ordering configuration. Certification should always be verified from the complete product identification and applicable documentation because not every 266GST configuration has the same approvals.

Maintenance and Troubleshooting

Routine maintenance of the 266GST should include inspection of the process connection, wiring, housing, display, and communication interface. The process connection should be checked for leakage or contamination, while electrical connections should be inspected for secure installation.

If the measured value appears incorrect, troubleshooting should begin by checking the process pressure, transmitter configuration, electrical supply, output signal, and communication settings. The sensor range and configured engineering unit should also be verified.

For digital communication systems, the associated configuration software, device description, driver, or fieldbus configuration should be checked according to the communication protocol used by the transmitter.

Technical Specifications Summary

Conclusion

ABB 266GST is a high-performance gauge pressure transmitter designed for industrial process measurement. It can measure liquid, gas, and steam pressure and can also be applied to level measurement in open tanks. Its flexible sensor ranges, communication options, local display functions, and available safety certifications allow the transmitter to be configured for different process automation requirements.

The 266GST provides a base accuracy of ±0.04%, with an optional ±0.025% accuracy configuration. Depending on the selected version, the transmitter can communicate through 4 to 20 mA with HART, PROFIBUS PA, or FOUNDATION Fieldbus.

For equipment replacement or system integration, the complete transmitter ordering code should be checked carefully because sensor range, process connection, communication protocol, display, materials, and certification can vary between configurations. Correct identification ensures that the selected ABB 266GST matches the required pressure measurement application and control system.