Schneider Electric Triconex 3721 | 3721 Analog Input Module

Product Description

Overview

The Triconex 3721 (Part No. 3721) is a high-reliability Analog Input Module engineered for integration with the Tricon™ Triple Modular Redundancy (TMR) system by Schneider Electric. Designed for mission-critical safety applications, this module provides accurate analog signal acquisition while ensuring fault tolerance and continuous operation. Its architecture guarantees that a single hardware or wiring fault does not compromise process safety or trigger unintended shutdowns.

Core Features

Triple Modular Redundancy (TMR) Architecture

• Three independent processing legs (A, B, C) with 2-out-of-3 voting logic

• Electrical isolation between legs to prevent fault propagation

• Continuous monitoring for "stuck-at" faults and signal drift

High-Precision Analog Performance

• 32 differential analog input channels

• Input voltage ranges: 0–5 VDC or ±5 VDC with ±6% tolerance

• Input current support: 4–20 mA via compatible termination panels

• Resolution: Selectable 12-bit or 14-bit

• Sampling/Update rate: 10 ms per channel

• Accuracy: Better than 0.15% of Full Scale Reading (FSR) from 0°C to 60°C

• Common-mode rejection: -85 dB (DC–100 Hz)

• Input overrange protection: 150 VDC / 115 VAC continuous

Industrial-Grade Design

• Weight: 1.36 kg; Shipping weight: 4 kg

• High immunity to EMI and vibration

• Certified for SIL 3 applications according to IEC 61508

• Hot-swappable module for online maintenance without process interruption

Technical Specifications

Applications

• Emergency Shutdown (ESD) Systems

• Fire & Gas (F&G) Monitoring

• Burner Management Systems (BMS)

• Turbomachinery Control (TMC)

Frequently Asked Questions

Q: Can the module be replaced while the system is running?
A: Yes, the Triconex 3721 supports hot-swapping without interrupting safety functions.

Q: Does the module support both voltage and current inputs?
A: Yes, it supports 0–5 VDC or ±5 VDC and 4–20 mA input signals (with appropriate external termination panels).

Q: Is the module suitable for SIL 3 systems?
A: Yes, it is designed and certified for SIL 3 safety-critical applications.

Q: How is signal accuracy ensured across harsh environments?
A: The module features continuous diagnostics, high common-mode rejection, and triple-leg voting to maintain signal integrity.