Description
The Triconex 3720 is a high-density, Triple Modular Redundant (TMR) Digital Output (DO) module designed for use in the Tricon safety-instrumented system (SIS). It provides 32 isolated output points, engineered specifically for mission-critical applications where high availability and safety integrity are mandatory.
Product Parameters (Datasheet)
- Model Number: 3720
- Module Type: TMR Digital Output (DO)
- Number of Points: 32 (Isolated)
- Nominal Voltage: 24V DC
- Output Voltage Range: 18–30V DC
- Current Rating: 0.5A per point (Maximum)
- Minimum Load: 10mA
- Leakage Current: < 2mA
- On-state Voltage Drop: < 1.5V at 0.5A
- Isolation: 1500V DC (Chassis to Output)
- Self-Test Frequency: Every 500ms (Internal diagnostics)
- Hot-Swappable: Yes
TRICONEX 3720
TRICONEX 3720
TRICONEX 3720
Country of Origin
This safety module was engineered and manufactured in the United States by Triconex (now a flagship brand of Schneider Electric).
Application Fields
The 3720 is a cornerstone of industrial safety, used extensively in:
- Emergency Shutdown (ESD): Controlling final elements like solenoid valves to safely halt a process.
- Fire & Gas (F&G) Systems: Activating alarms, beacons, and suppression systems.
- Burner Management Systems (BMS): Managing fuel valves and ignition sequences in large boilers.
- Nuclear Safety: Providing redundant control for cooling and containment systems.
- Turbo-Machinery Control: Interfacing with high-speed trip solenoids on turbines.
Product Usage Instructions
- Chassis Placement: Insert the 3720 module into any I/O slot of a Tricon v9 or v10 Main Chassis or Expansion Chassis.
- Termination: The module must be used with a corresponding External Termination Assembly (ETA) or a dedicated Tricon Field Termination Assembly (FTA) via a standard interface cable.
- Redundancy: To maintain the TMR safety rating, ensure the Tricon system’s three main processors (MPs) are active. The 3720 will automatically perform “2-out-of-3” voting on the output signals.
- Field Wiring: Verify that the field load (e.g., solenoid) does not exceed the 0.5A per point limit. Use shielded twisted-pair cables for environments with high electromagnetic noise.
- Diagnostic Monitoring: Monitor the “Active” and “Fault” LEDs on the front panel. A steady green “Active” LED indicates the module is participating in the TMR voting process.
Product Technical Description
The 3720 is a “Hi-Density” module, meaning it packs 32 points into a single slot without sacrificing safety. Technically, it employs Triple Modular Redundant (TMR) architecture. Each output point is governed by three separate branches of logic. These three branches are voted on by a specialized output circuit that ensures a single hardware failure (in one of the three paths) will not result in a “fail-to-danger” or a “nuisance trip” condition. The module also features comprehensive “Output Voter Manual” (OVM) diagnostics, which periodically exercise the output switches to detect hidden failures without affecting the state of the field load.
Q&A (Common Questions)
Q: What happens if one of the 32 points fails? A: Due to the TMR design, a single component failure on a branch will not change the output state. The module will report a “Fault” to the main processor, and the “Fault” LED will illuminate, allowing for a hot-swap replacement.
Q: Can this module drive high-current motors? A: No. The 3720 is rated for 0.5A per point. For higher current loads, it must drive an interposing relay or a larger contactor.
Q: Is the 3720 compatible with Tricon CX systems? A: The 3720 is designed for the “Legacy” Tricon (v9/v10) chassis. While Tricon CX can communicate with legacy systems, the physical 3720 card only fits into the standard Tricon rack.
Q: Does it support line monitoring? A: Yes, certain termination assemblies used with the 3720 can support supervised wiring to detect open or short circuits in the field wiring.
Similar Model Recommendations
- Triconex 3721: 24V DC Digital Output, 0.5A (Standard density/alternative revision).
- Triconex 3604E: 24V DC Digital Input module for TMR sensing.
- Triconex 3700: 115V AC Digital Output module for high-voltage logic.
- Triconex 3805H: Analog Output module for 4-20mA control loops.
- Triconex 3703E: Isolated Digital Output for specialized relay-like switching.
For technical datasheets or to check current stock for the Triconex 3720 and other safety-instrumented system spares, please contact our support team.
