Application Scenarios

At a liquefied natural gas (LNG) export terminal in Australia, a critical ESD valve failed to close during a simulated high-pressure event—triggering a plant-wide investigation. Root cause analysis revealed that a non-TMR digital output card in a legacy system had suffered a single-point latch-up failure. The facility replaced all such modules with TRICONEX 2351 units across its Tricon v10 SIS. During the next functional test, all 16 channels on each TRICONEX 2351 executed simultaneous, verified closures within 10 ms, with full agreement across all three voting legs. “This isn’t just an output card—it’s our last line of defense,” said the safety engineer. In applications where a single missed command could lead to environmental release or loss of life, the TRICONEX 2351 ensures deterministic, auditable action every time.

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Technical Principles and Innovative Values

Innovation Point 1: True TMR Output Voting – Unlike conventional DO cards, the TRICONEX 2351 receives three independent commands from the Tricon’s triple processors. Only if two out of three agree will the relay energize—eliminating spurious trips due to single-channel faults.

Innovation Point 2: Electromechanical Reliability Over Solid-State – By using gold-flashed, sealed relays instead of semiconductor switches, the TRICONEX 2351 avoids leakage current, thermal runaway, and false conduction—critical for fail-safe de-energize-to-trip (DTT) architectures.

Innovation Point 3: Comprehensive Diagnostic Coverage – Through Triconex Enhanced Diagnostic Monitor (EDM), users can detect relay coil failures, welded contacts, or broken field wiring before they compromise safety function—enabling predictive maintenance.

Innovation Point 4: Universal Load Compatibility – The relay-based design allows the TRICONEX 2351 to switch AC or DC, resistive or inductive loads without derating—simplifying engineering and reducing spare parts inventory.

Application Cases and Industry Value

During a refinery turnaround in Texas, engineers upgraded their F&G system from a simplex PLC to a Tricon SIS with TRICONEX 2351 modules driving deluge valve solenoids. Post-commissioning, a lightning strike induced a 5 kV surge on field wiring. While competing solid-state DO cards failed shorted (causing unintended water discharge), the TRICONEX 2351’s relays remained open—preventing millions in water damage and production loss. Similarly, in a nuclear auxiliary feedwater system, the module’s ability to prove contact status via EDM satisfied stringent regulatory requirements for periodic proof testing without manual intervention. Across industries, the TRICONEX 2351 is trusted where failure is not an option.

Related Product Combination Solutions

TRICONEX 3511E: 16-channel digital input (DI) module—often paired with TRICONEX 2351 for complete I/O loops

TRICONEX MP3008 / MP3009: Main processor chassis (v10) that hosts TRICONEX 2351 in I/O racks

TRICONEX 3700E (EDM): Enhanced Diagnostic Monitor software for real-time health tracking of TRICONEX 2351 channels

Asco 8210 Series Solenoids: Commonly driven by TRICONEX 2351 in ESD valve applications

Honeywell SM Series Relays: Used downstream for higher-power loads, triggered by TRICONEX 2351

TRICONEX 2352: Similar 8-channel version with higher current rating—alternative for heavy-duty actuators

ABB NTU-7C9-ABB: Not compatible—but fiber gateways may link Tricon to ABB 800xA for alarm visibility

GE Mark VIe VSDO: For hybrid turbine control where Tricon handles ESD and Mark VIe handles regulation

Installation, Maintenance, and Full-Cycle Support

Installation of the TRICONEX 2351 involves inserting it into a Tricon I/O chassis (e.g., MP3008) and connecting field devices to removable terminal blocks. No jumpers or DIP switches are required—the module is auto-configured by the Tricon controller. Field power (24–120 VAC/DC) must be supplied externally to the common terminals. During commissioning, output forcing and diagnostics are performed via Triconex Tools or EDM.

Maintenance is simplified by front-panel LEDs showing real-time channel status and EDM alerts for faults like “Relay Coil Open” or “Contact Welded.” Failed modules can be replaced hot in non-redundant racks, or during planned outages in safety-critical zones. As legacy Tricon hardware, genuine TRICONEX 2351 units are now provided through authorized reconditioning partners who perform full functional testing—including contact resistance, coil integrity, and TMR voting validation—per OEM specifications. Each unit ships with a test report, firmware version log, and traceable serial number for audit compliance.

Contact us for a customized solution—whether you’re maintaining an operational Tricon SIS, executing a safety system upgrade, or securing long-term spares for your SIL3 infrastructure. When lives and assets depend on a single output command, trust the TRICONEX 2351 to deliver it—safely, reliably, and without hesitation.