TRICONEX 3805E

Description

Product Overview

The TRICONEX 3805E is a high-performance, triple modular redundant (TMR) analog input module designed for the Triconex Tricon safety instrumented system (SIS). This module is engineered to provide the highest level of availability and fault tolerance for reading critical 4-20 mA process signals, such as those from pressure, level, and flow transmitters in safety-related applications. The primary function of the TRICONEX 3805E is to accept three independent 4-20 mA signals from a single field transmitter via isolated channels, perform continuous diagnostics and mid-value voting, and deliver a single, validated, high-integrity analog value to the TMR main processors.

Product Parameters and Specifications

• Function: TMR 4-20 mA Analog Input Module for Tricon System.
• Safety Standard: Designed and certified for use in Safety Instrumented Systems up to SIL 3 per IEC 61508/IEC 61511.
• Architecture: True Triple Modular Redundant (TMR). Each input point has three completely isolated input circuits.
• Input Signal: Accepts standard 4-20 mA current loop signals.
• Number of Channels: Typically provides 8 TMR analog input points (utilizing 24 physical field connections).
• Accuracy: High accuracy specification (e.g., ±0.1% of full scale) under defined conditions.
• Diagnostic Coverage: Very High (>99%). Continuous diagnostics include cross-channel comparison, open/short circuit detection, out-of-range detection, and internal hardware fault detection.
• Isolation: High-grade isolation between field-side channels, between the triplets, and from the system backplane.
• Update Rate: Fast and deterministic update rate synchronized with the Tricon controller scan.
• HART Support: Some variants may support HART digital communication superimposed on the 4-20 mA signal, allowing for bidirectional device configuration and diagnostics.

Advantages and Key Features

The TRICONEX 3805E offers unparalleled advantages for safety-critical analog monitoring. Its core strength is the hardware-based TMR architecture, which provides inherent fault tolerance. A single failure in wiring, the field transmitter, or one of the three internal input channels is masked by the voting logic, preventing a spurious trip or a dangerous undetected failure. This leads to extremely high system availability and a very low Probability of Failure on Demand (PFD). The module’s extensive diagnostic suite is capable of identifying the vast majority of dangerous failure modes. The TRICONEX 3805E supports hot-swappable replacement in online systems, allowing for maintenance without a process shutdown. Its design is optimized for integration with the Tricon system’s TriStation 1131 software, providing seamless configuration, calibration, and real-time diagnostic visibility.

Application Cases in Industry

This module is a standard component in TMR-based safety systems for the most hazardous processes. In Oil & Gas, the 3805E is used in offshore platform Emergency Shutdown (ESD) systems to monitor wellhead pressure, separator level, and gas detection concentrations. Within Refineries and Petrochemical Plants, it reads signals for reactor pressure, furnace tube temperature, and critical column levels to initiate safe shutdowns. For Power Generation, especially in turbine control and burner management systems, it provides fault-tolerant measurement of steam pressure, fuel flow, and drum level. The TRICONEX 3805E is also critical in LNG liquefaction trains and Pharmaceutical facilities where high-integrity analog measurement is required for safety interlocks.

Comparison with Competing Products

Compared to standard PLC or DCS analog input modules, the 3805E is in a different category, being specifically designed and certified for safety instrumented functions (SIF) with TMR redundancy. Its most direct competitors are other safety system vendors’ TMR analog input modules, such as those from ICS Triplex (Trusted TMR). Both offer TMR architecture and SIL 3 capability. Key differentiators often lie in the specific system architecture (Triconex uses a single-chassis TMR vs. some distributed architectures), diagnostic methodologies, module density, and the proprietary engineering toolset (TriStation). The choice between them frequently depends on existing plant standards, legacy system compatibility, and engineer familiarity.

Selection Suggestions and Precautions

• Selection Advice:
  1. Signal Type Verification: Confirm your field transmitters provide a standard 2-wire or 4-wire 4-20 mA output. The TRICONEX 3805E is designed for this signal type.
  2. System Compatibility: Ensure the module is compatible with your specific Tricon chassis model (e.g., Tricon v9, v10, v11) and main processor.
  3. HART Requirement: If you need to communicate with HART-enabled field devices, specify the HART-capable variant of the module at the time of purchase.
  4. Loop Power: Determine if the field transmitter requires loop power. Some variants may supply loop power; others may require an external isolated supply.
• Important Precautions:
  1. Wiring Segregation: For true fault tolerance, the three independent wires for each TMR input point must be physically routed in separate cables or conduits. Failure to do so compromises the TMR architecture and can create a common cause failure.
  2. Calibration: While the module is highly stable, the entire loop (transmitter, wiring, 3805E input) should be calibrated periodically as part of the proof testing regime to maintain the SIF’s safety performance.
  3. Grounding and Shielding: Follow Triconex installation guidelines precisely for shield grounding on analog cables. Typically, the shield should be grounded at one end only (usually in the marshalling cabinet) to prevent ground loops.
  4. Configuration: The module’s parameters (engineering units, range, diagnostics) must be correctly configured in the TriStation 1131 software. An incorrectly configured safety input is a dangerous failure.

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