The TRICONEX 3625​ is a triple modular redundant (TMR) contact output module designed for the Tricon safety instrumented system. Its primary function is to serve as a highly reliable, fail-safe interface that executes voted safety commands from the TMR controller by actuating critical final elements in the field. It provides a physical, dry contact closure to energize devices such as solenoid valves, shutdown valves, motor starters, and alarm annunciators, bringing a process to a predefined safe state upon the detection of a hazardous condition.

Triple Redundant, Fault-Tolerant Output Voting:

Each output channel on the TRICONEX 3625​ is implemented with three independent solid-state switches, one per TMR channel. The outputs are physically wired in a series-parallel configuration to a single field device. The TMR controller logic drives all three switches. For the output to be energized (ON), at least two of the three channels must command it ON. This 2-out-of-3 (2oo3) voting scheme ensures that a single fault within the module—a failed switch or a fault in one processor channel—will not prevent a required safety action from occurring, nor will it cause a spurious, unsafe activation.

High-Current Capacity with Diagnostics:

The module features robust, high-current-rated output contacts capable of directly driving inductive loads common in industrial settings. It incorporates comprehensive diagnostics to monitor the health of each output channel. These diagnostics can detect faults such as open load (wire break), short-circuit conditions, and internal module failures. Diagnostic status is reported back to the main processor, enabling predictive maintenance and immediate awareness of any output circuit impairment.

Fail-Safe De-energize-to-Trip Design:

The TRICONEX 3625​ adheres to the fundamental safety principle of “de-energize to trip.” In its normal, non-activated state, the output contacts are open. When the safety logic demands an action, the module closes the contacts to energize the field device (e.g., to close a shutdown valve). In the event of a loss of system power, module failure, or a confirmed fault, the outputs will inherently default to the open (de-energized) state, driving the process to its safe condition. This design provides a predictable and reliable failure mode.

Online Replacement and High Availability:

The module supports online, hot-replacement procedures. If a fault is diagnosed, the TRICONEX 3625​ can be safely removed and replaced while the Tricon system remains operational. The TMR architecture ensures that the remaining two healthy channels for each output continue to perform the voting function, maintaining the safety system’s availability and allowing maintenance without a process shutdown.

The TRICONEX 3625​ is deployed to actuate final elements in critical safety shutdown sequences. Its primary applications are in Emergency Shutdown (ESD) systems for oil & gas facilities to close shutdown valves, in Fire & Gas (F&G) systems to activate deluge valves or fire pumps, and in Burner Management Systems (BMS) to shut off fuel valves. It is also used in turbine and compressor protection systems to initiate emergency stops and in process industries to activate critical alarms or backup systems.

A high-density TMR digital input module. It acquires the safety-critical status signals (e.g., from pressure switches or emergency stops) that the logic solver uses to make a decision. The TRICONEX 3625​ is the complementary module that executes the resulting action command.

A TMR analog input module. While the TRICONEX 3625​ handles discrete outputs, the 3721​ handles critical analog signals (e.g., pressure, temperature). The safety logic solver uses inputs from modules like the 3721​ to make complex decisions, which may then result in outputs via the 3625.

The Main Processor Module. The TRICONEX 3625​ receives its voted command signals from the TRICONEX 4351B. The main processor executes the safety application logic and sends independent output commands to each of the three channels within the 3625​ module, which then performs the final hardware voting.