Description

The ABB AI845 is a highly specialized, 8-channel analog input module designed exclusively for temperature measurement applications within ABB’s Symphony™ Plus and Advant® Controller 400 distributed control system (DCS) families. This module is a critical component for accurate and reliable process temperature monitoring, directly interfacing with a wide variety of resistance temperature detectors (RTDs) and thermocouples without the need for external signal transmitters. The ABB AI845 performs all necessary signal conditioning, linearization, and conversion within the module itself, delivering high-resolution digital values representing precise temperature readings to the central controller for display, logging, and control purposes.

Engineered for operational excellence in harsh industrial environments, the ABB AI845 provides exceptional noise immunity and electrical isolation. Each input channel is fully isolated from the others and from the system bus, protecting the integrity of the often low-level millivolt signals from thermocouples and RTDs against electromagnetic interference (EMI) and ground loops. This robust design ensures that the delicate temperature data remains accurate and uncompromised. As a member of the versatile S800 I/O family, the ABB AI845 supports hot-swapping, allowing for maintenance and replacement without a system shutdown, which is crucial for minimizing downtime in continuous process operations. The reliability and precision of the ABB AI845 make it an indispensable asset for any process where temperature is a critical-to-quality variable.

AI845 ABB

Technical Specifications

Parameter Name	Parameter Value
Product Model	AI845
Manufacturer	ABB
Product Type	Temperature Input Module (S800 I/O)
Number of Channels	8
Supported Sensors	RTDs (Pt100, Ni100, Ni120, Cu10, etc.), Thermocouples (J, K, T, E, R, S, B, N, C)
Measurement Resolution	0.1 °C / 0.1 °F
Accuracy	±0.1% of reading (for Pt100)
Update Time	500 ms per module (all channels)
Input Break Detection	Yes (Open circuit detection for all sensor types)
Isolation	1500 V AC (channel-to-channel and channel-to-bus)
Sensor Excitation	Current source for RTDs; reference junction compensation for T/Cs
Operating Temperature	0 to 60 °C (32 to 140 °F)

Main Features and Advantages

The ABB AI845 module stands out due to its dedicated focus on high-fidelity temperature measurement and advanced integrated functionality. A primary feature is its built-in intelligence for sensor management. The module automatically provides the correct excitation current for RTD measurements and incorporates a highly accurate cold junction compensation (CJC) circuit for thermocouple inputs, eliminating the need for external hardware and reducing potential points of failure. Each channel is individually configurable via software, allowing a single ABB AI845 module to support a mix of different RTD types and thermocouple types across its eight channels, offering tremendous flexibility.

Diagnostic capabilities are a core advantage of the ABB AI845. It continuously performs self-diagnostics and monitors all connected sensors for critical faults such as open circuits, short circuits, and out-of-range signals. These diagnostics are reported directly to the control system, enabling predictive maintenance and allowing operators to address sensor issues before they impact process quality or cause unscheduled downtime. The module’s high level of internal isolation ensures that even a failure on one channel, such as a high-voltage surge, will not propagate to adjacent channels or damage the backplane, safeguarding the entire control loop and ensuring overall system resilience.

Application Field

The ABB AI845 is deployed across process industries where precise and reliable temperature monitoring is essential for safety, quality, and efficiency. In the oil and gas sector, it is used to monitor critical temperatures in distillation columns, catalytic crackers, furnace tubes, and pipeline pump stations. In power generation, the module is essential for measuring bearing temperatures in turbines and generators, monitoring boiler temperatures, and ensuring optimal performance of heat exchangers and condensers.

The chemical and pharmaceutical industries rely on the ABB AI845 for batch and continuous process control, where exact temperature profiles are crucial for reaction kinetics, product consistency, and regulatory compliance. It is found controlling reactor jacket temperatures, monitoring storage tank conditions, and overseeing distillation processes. In pulp and paper manufacturing and metals processing, the module is used to measure temperatures in rolling mills, drying ovens, and digesters. The ABB AI845 is the preferred solution for any application within an ABB DCS that demands robust, accurate, and fault-tolerant temperature measurement.

AI845 ABB

Related Products

AO845: An analog output module often used in control loops where a temperature controller’s output drives a final control element.

AI840: A general-purpose analog input module for standard 4-20mA signals, complementing the temperature-specific AI845.

CI841: A communication interface module that connects the S800 I/O rack, housing the AI845, to the higher-level controller.

DI810: Digital input module for integrating discrete status signals into the same control system.

TU810: A temperature transmitter module that can be used as an alternative or complementary solution for specific signal conditioning needs.

S800 I/O Rack (e.g., TB801 or TB811): The physical mounting and connectivity unit required for installing the module.