Triconex DO3625 (3625) 24VDC Digital Output Module

The Triconex DO3625 (commonly referred to as Model 3625) is a high-density, Triple Modular Redundant (TMR) digital output module designed exclusively for Triconex Tricon safety instrumented systems (SIS). Developed by Triconex (now part of Schneider Electric), this module is engineered to execute critical control commands by driving field devices in safety-critical industrial environments. It serves as the vital interface between the Tricon controller’s safety logic and physical actuators, ensuring fail-safe and fault-tolerant operation.

Featuring a robust TMR architecture, the 3625 module contains three independent signal paths. Output commands are voted on by a fault-tolerant output circuit, guaranteeing that a single component failure will not compromise the output signal. It supports both supervised and non-supervised output modes, offering unparalleled flexibility for diverse safety and control requirements. Comprehensive on-board diagnostics continuously monitor channel health, field wiring integrity, and load status, making it a cornerstone of predictive maintenance in high-availability systems.

The Triconex 3625 is deployed exclusively in safety-critical and high-reliability applications where a false output or failure could lead to significant risk. Key application areas include:

Oil & Gas: Emergency Shutdown (ESD) valves, wellhead isolation, pipeline shutoff, and fire & gas (F&G) alarm systems.
Petrochemical & Refining: Burner management systems (BMS), process interlocks, pump/motor starter control, and safety relief valve actuation.
Power Generation: Turbine control, boiler safety systems, and auxiliary plant safety shutoffs.
Chemical & Pharmaceutical: Reactor safety interlocks, emergency ventilation, and critical process isolation.
Mining & Metals: Conveyor safety, mill shutdown, and fire suppression systems.

Its core functions are to:

Drive solenoid valves, relays, indicator lights, and motor starters.
Execute safety interlock and emergency shutdown commands.
Provide supervised outputs to continuously verify field device and wiring integrity.
Interface with Tricon main processors for high-integrity, voted control signals.

Key Technical Specifications

General

Model: Triconex 3625 (DO3625)
Type: TMR Digital Output Module (Supervised/Non-Supervised)
Channels: 32 output points (commoned)
System Compatibility: Tricon v9, v10, and subsequent series
Form Factor: Rack-mounted module for Tricon chassis
Hot-Swappable: Yes, replacement without system shutdown

Electrical Ratings

Nominal Voltage: 24 VDC
Voltage Range: 16–32 VDC
Maximum Current per Point: 1.7 A
Surge Current: 7 A (for 10 ms)
Minimum Load: 10 mA (for supervision)
Channel Isolation: 1500 VDC
Power Consumption: <13 watts

Mechanical & Environmental

Operating Temperature: -20°C to +60°C
Relative Humidity: 5% to 95% (non-condensing)
Weight: Approx. 0.8–1.2 kg
Certifications: IEC 61508 SIL 3 capable

Key Features

Triple Modular Redundancy (TMR): Three independent channels with voting logic for zero single-point failure.
Supervised Outputs: Continuous loop-check diagnostics to detect open circuits, short circuits, and missing loads.
Comprehensive Status LEDs: PASS, FAULT, ACTIVE, and individual channel status indicators.
Self-Protected Circuits: No external fuses required; over-current protection per channel.
High-Density Design: Maximizes I/O capacity within minimal rack space.
Industrial Ruggedness: Designed for continuous operation in harsh industrial environments.