Description
The Triconex 3708EN is a high-density, Triple Modular Redundant (TMR) Analog Input Module designed for use in Tricon safety-instrumented systems (SIS). It provides 16 differential isolated input channels, specifically engineered for critical applications requiring the highest levels of safety and availability, such as Emergency Shutdown (ESD) and Fire and Gas (F&G) systems.
Product Parameters (Datasheet)
- Model Number: 3708EN
- Module Type: TMR Analog Input (Enhanced)
- Number of Channels: 16, differential isolated
- Input Range: 0 to 5 VDC or 4 to 20 mA (using external 250-ohm resistor)
- Resolution: 12-bit
- Accuracy: < 0.15% of FSR (0 to 5 VDC)
- Input Impedance: > 10 MOhms (Voltage mode)
- Isolation: 1000 VDC (Channel-to-channel and channel-to-chassis)
- Scan Rate: 50 ms (nominal)
- System Compatibility: Tricon v9.6 and higher / v10.x systems
TRICONEX 3708EN
TRICONEX 3708EN
TRICONEX 3708EN
Country of Origin
This safety-critical module is engineered and manufactured by Triconex (a brand of Schneider Electric) in the USA.
Application Fields
The 3708EN is the gold standard for high-integrity process protection:
- Emergency Shutdown (ESD): Monitoring critical pressures and temperatures to trigger plant-wide safety trips.
- Fire and Gas (F&G) Systems: Interfacing with flame and toxic gas detectors.
- Boiler Management Systems (BMS): Ensuring safe fuel-to-air ratios and drum levels.
- Nuclear Safety: Used in non-safety and safety-related monitoring loops.
- High Pressure Protection (HIPPS): Providing rapid isolation for pipelines and pressure vessels.
Product Usage Instructions
- Chassis Placement: Insert the 3708EN into any I/O slot of a Tricon TMR chassis. Ensure the module is fully seated and the top/bottom fasteners are tightened.
- Termination: Use the appropriate External Termination Panel (ETP) to connect field wiring. For 4-20mA signals, ensure the precision 250-ohm shunt resistors are installed at the ETP.
- Redundancy: As a TMR module, the 3708EN contains three independent input legs. Ensure the system is configured in TriStation 1131 to treat the module as a TMR point.
- Hot Swapping: This module is hot-swappable. When replacing, wait for the “Active” light on the new module to turn green before removing the redundant partner if applicable.
- Diagnostics: Monitor the “PASS,” “FAULT,” and “ACTIVE” LEDs on the front panel to verify the health of the three internal microprocessors.
Product Technical Description
The 3708EN utilizes Triconex’s signature Triple Modular Redundant (TMR) architecture. Each of the 16 input signals is split into three separate paths. Three independent microprocessors (Legs A, B, and C) perform their own A/D conversion and signal conditioning. The results are then shared and “voted” upon by the main Tricon processors. This ensures that even if one internal component fails, the module continues to provide correct data to the safety logic without interruption. The “EN” designation stands for “Enhanced,” featuring improved diagnostic coverage and better noise rejection compared to the legacy 3708 models.
Q&A (Common Questions)
Q: Can I use this module for thermocouples directly? A: No, the 3708EN is a 0-5V / 4-20mA module. For thermocouples, you should use the 3706A or 3702 series modules, or use external signal conditioners.
Q: What is the difference between the 3708E and 3708EN? A: The “EN” version is the newest revision, providing higher accuracy and enhanced self-diagnostic capabilities for internal circuitry health monitoring.
Q: Does it support HART communication? A: The 3708EN is an analog-only module. For HART pass-through capabilities, the 3721 or newer 3723 modules are required.
Q: Is it possible to use this in a non-TMR (Simplex) configuration? A: While Tricon hardware can technically run in degraded modes, the 3708EN is fundamentally a TMR module and should always be used in a TMR environment to maintain safety certifications (SIL 3).
Similar Model Recommendations
- Triconex 3708E (Standard Enhanced AI)
- Triconex 3721 (HART Analog Input Module)
- Triconex 3805E (Analog Output Module)
- Triconex 3503E (Digital Input Module)
- Triconex 3625 (Digital Output Module)
For more information on the Triconex 3708EN and our full inventory of Triconex safety parts, please contact our technical sales team.
