Description

The Triconex 5351 is a 32-channel digital output (DO) module engineered for the Tricon® and Triconex® Triple-Modular Redundant (TMR) safety instrumented systems (SIS), developed by Schneider Electric. Designed to meet the highest functional safety standards—including SIL 3 per IEC 61508 and IEC 61511—the Triconex 5351 provides fail-safe actuation of field devices such as solenoid valves, motor starters, and alarm annunciators in mission-critical applications where process integrity and personnel safety are paramount. Unlike conventional PLC outputs, the Triconex 5351 operates within a fully fault-tolerant architecture: three independent processing channels vote on every output command, ensuring that no single hardware failure can cause an unsafe condition.

As part of the enhanced 53xx series, the Triconex 5351 supports both 120 VAC and 120 VDC loads per channel, with individual channel diagnostics, short-circuit protection, and open-wire detection. It integrates seamlessly into Tricon v10 and v11 chassis, communicating with the main processors via the high-speed TriBus™ backplane. Each output is electrically isolated and capable of driving inductive or resistive loads up to 2 A per channel (with derating at elevated temperatures). The Triconex 5351’s robust design—featuring conformal coating, wide temperature tolerance, and immunity to EMI—makes it a staple in oil & gas refineries, chemical plants, power generation facilities, and water treatment infrastructure where reliability under stress is non-negotiable.

Technical Specifications

Main Features and Advantages

Triple-modular redundancy with zero single point of failure: The Triconex 5351 operates within Triconex’s patented TMR architecture, where three independent microprocessors execute the same logic and compare results before energizing any output. If one channel fails, the other two override it—ensuring safe state enforcement without interruption. This makes the Triconex 5351 suitable for emergency shutdown (ESD), fire & gas (F&G), and burner management systems where failure could result in catastrophic consequences.

Comprehensive real-time diagnostics for predictive maintenance: Every channel on the Triconex 5351 continuously monitors load current, detects open wires, short circuits, and overloads, and reports faults to the controller without affecting other channels. These diagnostics are accessible via Triconex’s Enhanced Diagnostic Monitor (EDM) software, enabling operators to identify degrading components before they cause spurious trips—a key requirement for achieving high proof test intervals under IEC 61511.

Wide voltage compatibility and high drive capability: Supporting both AC and DC loads up to 150 V, the Triconex 5351 eliminates the need for external interposing relays in most applications. Its 2 A per-channel rating allows direct control of pilot-duty solenoids, indicator lamps, and small contactor coils—simplifying panel design and reducing component count, which in turn improves overall system reliability.

Hot-swappable and backward compatible: The Triconex 5351 can be replaced during operation without powering down the entire Tricon system—minimizing downtime in continuous-process industries. It is also pin-compatible with earlier models like the 5350, allowing seamless upgrades with no wiring changes, protecting legacy engineering investments while enhancing diagnostic depth and thermal performance.

Robust construction for extreme environments: With conformal-coated PCBs, ruggedized connectors, and immunity to industrial noise (tested per IEC 61000-4), the Triconex 5351 performs reliably in offshore platforms, desert compressor stations, and arctic LNG facilities. Optional ATEX certification extends its use into Zone 2 hazardous areas.

Application Field

The Triconex 5351 is predominantly used in safety-critical process industries where regulatory compliance and operational continuity are inseparable. In oil & gas upstream and midstream operations, it actuates emergency isolation valves (EIVs) on pipelines and wellheads during high-pressure or leak events, forming the final control element layer of a SIL 3-certified SIS. In refineries and petrochemical plants, the Triconex 5351 drives blowdown valves, deluge system triggers, and reactor dump mechanisms in response to temperature or pressure excursions detected by redundant sensors.

In power generation, particularly in combined-cycle and nuclear facilities, the Triconex 5351 interfaces with turbine trip solenoids, generator breaker controls, and auxiliary shutdown systems—ensuring rapid, fail-safe responses to overspeed or loss-of-coolant scenarios. Similarly, in water and wastewater infrastructure, it manages chlorine injection cutoffs and pump station emergency stops to prevent environmental contamination. Because the Triconex 5351 delivers certified safety performance without sacrificing diagnostic transparency, it remains the output module of choice for engineers designing systems where “safe failure” is not just a requirement—but a legal and ethical obligation.

Related Products

5350: Predecessor to 5351; similar specs but fewer diagnostics and lower thermal rating.
5331: 32-channel TMR digital input module—often paired with 5351 in ESD loops.
5361: Analog output module (4–20 mA) for modulating valve control in safety systems.
5300: Base terminal block assembly used with 5351 for field wiring.
5301: Removable terminal block (RTB) for 5351, enabling quick disconnect during maintenance.
Tricon MP3008: Main processor module compatible with 5351 in v10/v11 systems.
Triconex EDM Software: Diagnostic tool for monitoring 5351 channel health and fault logs.
5371: High-density digital output (64-channel) variant for space-constrained cabinets.