Description

The SIS AI3281 is a highly specialized 8-channel analog input safety module designed for critical safety applications within HIMA’s HIMax Safety Instrumented System (SIS) platform. This module serves as the primary interface for acquiring analog signals from field instruments in safety-critical processes, such as pressure transmitters, temperature sensors, and level switches, where failure could lead to hazardous events. The SIS AI3281 is engineered to meet the stringent requirements of Safety Integrity Level (SIL) 3 per IEC 61508 and IEC 61511 standards, providing the highest level of functional safety assurance for emergency shutdown (ESD), fire and gas (F&G), and burner management systems (BMS).

Unlike standard analog input modules, the SIS AI3281 incorporates redundant internal architectures and advanced self-diagnostic capabilities that continuously monitor the health of both the module itself and the connected field devices. This design ensures that any潜在 faults, such as wire breaks, short circuits, or internal component failures, are detected and managed appropriately to maintain the required safety integrity. The module features robust galvanic isolation between channels and from the system bus, protecting against ground loops and electromagnetic interference (EMI) that could compromise signal integrity in industrial environments. The SIS AI3281 is an essential component in any safety loop where reliable acquisition of analog process variables is crucial for making automated safety decisions.

AI3281 SIS

Technical Specifications

Parameter Name	Parameter Value
Product Model	AI3281
Manufacturer	SIS
Product Type	Safety Analog Input Module (HIMax Platform)
Safety Integrity Level	SIL 3 (IEC 61508/61511)
Number of Channels	8
Input Signal Type	4-20 mA (2-wire and 4-wire transmitters)
Resolution	16 bits
Accuracy	±0.1% of full scale
Update Time	< 500 ms (per channel group)
Diagnostic Coverage	> 90%
Hardware Fault Tolerance	1
Isolation	1500 V AC (channel-to-channel and channel-to-bus)
Operating Temperature	-40 to +70 °C (-40 to +158 °F)
Certifications	ATEX, IECEx, UL, CE

Main Features and Advantages

The AI3281 offers exceptional safety performance through its fault-tolerant design and comprehensive diagnostic suite. Its most critical feature is the built-in HART protocol support, which allows for advanced device diagnostics, configuration, and calibration of smart field instruments without compromising the safety function. This enables predictive maintenance strategies for safety-critical instrumentation. The module employs a redundant architecture with two independent measurement paths per channel, allowing continuous cross-comparison and validation of signals to detect discrepancies that might indicate a developing fault.

Advanced diagnostics: The module continuously performs self-tests on its internal circuitry, including the analog-to-digital converters, reference voltages, and signal conditioning components. It also monitors field wiring for open circuits, short circuits, and out-of-range signals. Any detected fault is immediately reported to the central safety controller and can be configured to trigger a specific safe reaction. The high degree of isolation ensures that a failure on one channel cannot affect adjacent channels or the system bus, maintaining overall system integrity. The HIMA AI3281 is designed for easy integration and configuration through HIMA’s dedicated engineering tools, streamlining the implementation of complex safety functions.

Application Field

The AI3281 is deployed in the most demanding safety-critical applications across process industries where the highest level of functional safety is required. In oil and gas facilities, it is essential for emergency shutdown systems (ESD) that monitor critical parameters such as pipeline pressure, vessel level, and compressor discharge temperature to initiate safe shutdowns during abnormal conditions. In chemical and petrochemical plants, the module is used in safety interlocks and fire and gas systems to detect hazardous gas concentrations, high reactor temperatures, or pressure excursions that could lead to dangerous situations.

Power generation facilities utilize the AI3281 in burner management systems (BMS) to monitor flame status, fuel pressure, and furnace draft pressure, ensuring safe boiler operation and preventing catastrophic explosions. In offshore platforms and LNG terminals, the module provides reliable safety monitoring where environmental conditions are particularly harsh and equipment failure could have severe consequences. The AI3281 is the preferred choice for any application where SIL 3 certification is required for analog input functions and where the highest reliability in safety signal acquisition is non-negotiable.

AI3281 SIS

Related Products

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