1746-NR4 Allen-Bradley Resistance Temperature Detector Module

Product Overview

The Allen-Bradley 1746-NR4 is a high-precision RTD (Resistance Temperature Detector) input module designed for the SLC 500™ controller platform. This module provides four backplane-isolated channels capable of interfacing with a variety of RTD sensors to provide accurate temperature data for industrial processes. With built-in linearization and self-calibration features, the 1746-NR4 ensures high-fidelity signal conversion and long-term stability in demanding thermal monitoring applications.

Technical Configuration

• Manufacturer: Allen-Bradley / Rockwell Automation
• Product Line: SLC 500 I/O
• Catalog Number: 1746-NR4
• Number of Channels: 4 (Backplane Isolated)
• Backplane Current Draw: 50 mA at 5V DC; 50 mA at 24V DC
• Isolation Voltage: 500 Volts for 1 minute
• Terminal Wire Size: Up to two 2.5 mm² (14 AWG) per terminal

Technical Specifications

Installation & Wiring Features

1. Signal Isolation: The 1746-NR4 features 500V operating isolation between the RTD inputs and the backplane. This protects the SLC 500 CPU from electrical noise and potential transients originating from field sensors, ensuring system-wide reliability in electrically noisy environments.

2. Wiring Capacity: The module supports a maximum termination wire size of two 2.5 mm² (14 AWG) wires per terminal. This allows for robust physical connections and facilitates "daisy-chaining" of common leads where required by specific RTD configurations (2-wire, 3-wire, or 4-wire).

3. Thermal Management: Designed to operate efficiently within a range of 0 to 60 °C, the module consumes a maximum of 1.5W of power. Its low heat dissipation footprint allows it to be installed in high-density SLC 500 racks without requiring specialized cooling, provided standard enclosure ventilation is maintained.

Engineering Advantages

The Allen-Bradley 1746-NR4 is engineered for precision. By converting analog resistance signals directly into digital values for the SLC 500 backplane, it eliminates the need for external signal conditioners. The module's compatibility with standard certifications (CE, UL, C-Tick) ensures it meets global safety and electromagnetic compatibility standards, making it a dependable choice for international machinery manufacturers and process plants.

Technical FAQs

Q1: What types of RTDs does the 1746-NR4 support?
A1: The module is designed to work with standard Platinum, Nickel, and Copper RTDs. Please refer to the user manual for specific resistance curves and configuration settings.

Q2: Is an external power supply required?
A2: No, the 1746-NR4 draws its required operating power (50 mA at 5V and 24V DC) directly from the SLC 500 chassis backplane.

Q3: Can channels be configured independently?
A3: Yes, each of the four channels is isolated and can be configured through the controller software to match the specific RTD type connected to that port.