Invensys Triconex 3721 TMR Analog Input Module

Introduction: Analog Input (AI) Modules are designed to receive variable voltage signals, convert them to digital values, and transmit these values to the Main Processor modules. These modules support Triple Modular Redundancy (TMR) mode, ensuring data accuracy through a mid-value selection algorithm. Each module conducts ongoing diagnostics and supports hot-spare capability for online replacement. They require an external termination panel (ETP) and are keyed for proper installation in a Tricon chassis.

Module Specifications

Model Numbers: 3721

Voltage:

• 3721: 0 to 5VDC or -5 to +5VDC, +6%

Type: TMR, AI

Number of Input Points:

• 3721: 32 differential, DC-coupled

Isolated Points:

• 3721: Yes

Input Update Rate:

• 3721: 10 ms

Resolution:

• 3721: 12 bits or 14 bits programmable

Accuracy:

• 3721: < 0.15% of FSR from 0° to 60°C

Input Resistance (load):

• 3721: 10 MΩ (DC), minimum

Power-Off Resistance:

• 3721: 140 kΩ (DC), typical

Common Mode Rejection:

• 3721: -85 dB (DC - 100 Hz)

Common Mode Range:

• 3721: -12V to +12V peak

Leg-to-Leg Isolation:

• 3721: 420 kΩ, typical

Normal Mode Rejection:

• 3721: -3 dB @ 23Hz, -8 dB @ 60Hz, -14 dB @ 120Hz

Input Overrange Protection: 150 VDC/115 VAC continuous

Current Range:

• 3721: 0-20 mA with 250 Ω shunt resistor

Diagnostic Indicators:

• 3721: PASS, FAULT, ACTIVE, FIELD

Color Code:

• 3721: Yellow

Weight: 4.7 to 6.0 lbs. (2.1 kg. to 2.7 kg.)

Conclusion Analog Input Modules, with their various specifications and diagnostic capabilities, are essential for ensuring accurate and reliable data transmission in critical applications. Their support for TMR mode, ongoing diagnostics, and hot-spare capability makes them suitable for robust and fault-tolerant systems.