Triconex 3704E 64-Ch Analog Input 0-5/10V TMR

Product Overview

The 3704E is a 64-channel high-density analog input module manufactured by Invensys Triconex for the Tricon safety instrumented system. It provides TMR-protected acquisition of voltage and current signals from field transmitters, converting analog process variables into digital data for safety logic execution. With 0–5 VDC and 0–10 VDC voltage ranges plus 0–20 mA current capability via external shunt resistors, the 3704E delivers maximum channel density for large-scale process monitoring applications.

Key Specifications

• System: Invensys Triconex Tricon SIS
• Type: TMR Analog Input Module
• Channels: 64 single-ended inputs
• Voltage Range: 0–5 VDC / 0–10 VDC
• Current Range: 0–20 mA (requires 250 Ω or 500 Ω external shunt)
• Resolution: 12 bits
• Accuracy: Better than 0.25% of full scale (0°C to 60°C)
• Input Resistance: ≥ 30 MΩ (powered), 30 kΩ typical (powered off)
• Leg-to-Leg Isolation: 200 kΩ typical
• Normal Mode Rejection: -1 dB at 8 Hz, -12 dB at 60 Hz, -18 dB at 120 Hz
• Input Overrange Protection: 150 VDC / 115 VAC continuous
• Scan Time: 75 ms for all 64 points
• Power Consumption: 20 W typical
• Operating Temperature: 0°C to +60°C

Features & Benefits

1. Ultra-High Channel Density: 64 single-ended inputs in one module minimize rack slots for large I/O counts in safety systems.
2. TMR Signal Voting: Each input is processed by three independent channels with mid-value selection, ensuring correct data despite single-channel failures.
3. Voltage and Current Flexibility: Direct 0–5V/0–10V inputs plus 0–20mA capability via shunt resistors accommodate diverse transmitter types.
4. High Input Impedance: 30 MΩ minimum input resistance prevents loading effects on voltage signal sources.
5. Overvoltage Protection: 150 VDC / 115 VAC continuous protection safeguards the module from wiring errors and field transients.

FAQ

Q: Does the 3704E provide channel-to-channel isolation?
A: No, the 3704E is a non-isolated, commoned-input module designed for high density. For isolated analog inputs, select the 3703E (16-channel isolated AI).

Q: What shunt resistor is needed for 4–20 mA inputs?
A> Use a 250 Ω precision resistor to convert 4–20 mA to 1–5 VDC for the 0–5V range, or a 500 Ω resistor for 2–10 VDC on the 0–10V range.

Q: What is the difference between 3704E and 3721?
A> The 3704E provides 64 single-ended non-isolated inputs. The 3721 provides 32 differential DC-coupled inputs with higher noise immunity for critical measurements.

Installation Guide

• Install the module into a Tricon analog input slot in the chassis.
• Wire field transmitters to the external termination panel (ETP) using shielded cable.
• For current loops, install 250 Ω or 500 Ω shunt resistors at the ETP terminals.
• Ground cable shields at one end only (typically at the ETP ground bus) to prevent ground loops.
• Verify input accuracy by comparing module readings against a calibrated handheld meter at 0%, 50%, and 100% span.

Selection Tips

• Isolation Requirements: Use the 3704E when galvanic isolation is not required between channels. For mixed ground potential environments, specify the isolated 3703E or 3708E.
• Signal Type: The 3704E is ideal for voltage transmitters (0–5V, 0–10V). For direct 4–20 mA input without external shunts, consider the 3805E analog output or other current-input modules.
• Scan Time: The 75 ms update rate suits standard process control. For faster loops, verify Tricon scan configuration or select modules with higher update rates.