Overview

The Allen-Bradley 1746-NR8 is an RTD/Resistance Input Module designed for use in industrial automation systems. It provides reliable temperature and resistance measurement capabilities, ensuring precise and accurate data for various control applications.

Technical Specifications

• Backplane Current Consumption:
  • 100 mA at 5V DC
  • 55 mA at 24V DC
• Backplane Power Consumption: 1.82W maximum (0.5W at 5V DC, 1.32W at 24V DC)
• External Power Supply Requirements: None
• Number of Channels: 8 (backplane isolated)
• I/O Chassis Location: Any I/O module slot except slot 0
• A/D Conversion Method: Sigma-Delta Modulation
• Input Filtering: Low pass digital filter with programmable notch (filter) frequencies
• Normal Mode Rejection (between [+] input and [-] input):
  • 65 dB minimum at 50/60 Hz with 50/60 Hz filter
  • 110 dB minimum at 50 Hz with 28 Hz filter
  • 95 dB minimum at 60 Hz with 28 Hz filter
• Max. Common Mode Voltage: ±1 volt
• Max. Allowed Permanent Overload:
  • Volts: ±5V DC
  • Current: ±5 mA
• Input Filter Cut-Off Frequencies:
  • 7.80 Hz at 28 Hz filter frequency
  • 13.65 Hz at 50/60 Hz filter frequency
  • 209.6 Hz at 800 Hz filter frequency
  • 1676 Hz at 6400 Hz filter frequency
• Calibration: Module autocalibrates at power-up. Periodic calibration (every 5 minutes) can also be enabled.
• Isolation: 500V AC for 1 minute between inputs and chassis ground, and between inputs and backplane. 5V DC continuous between channels.

Physical Specifications

• LED Indicators: 9 green status indicators, one for each of 8 channels and one for module status
• Module ID Code: 3508 - Class 1, 12708 - Class 3
• Maximum Termination Wire Size: One 14 AWG wire per terminal
• Maximum Cable Impedance: 25 ohms maximum impedance for 3-wire RTD configuration
• Terminal Block: 1746-RT-35

Environmental Specifications

• Operating Temperature: 0°C to +60°C (+32°F to +140°F)
• Storage Temperature: -40°C to +85°C (-40°F to +185°F)
• Relative Humidity: 5% to 95% (without condensation)
• Agency Certification: UL and C-UL approved
• Hazardous Environment Classification: Class I, Division 2 Hazardous Environment Groups A, B, C, D
• EMC: CE compliant for all applicable directives
• C-Tick: Compliant for all applicable acts

Input Specifications

• RTD Types: Platinum, nickel, nickel iron, copper
• Temperature Scale (Selectable): °C or °F and 0.1°C or 0.1°F
• Resistance Scale (Selectable):
  • 1Ω or 0.1Ω for all resistance ranges except for 150Ω; or
  • 0.1Ω or 0.01Ω for 150Ω potentiometer.
• Input Step Response: Refer to the SLC 500™ RTD/Resistance Input Module User Manual, publication number 1747-UM003A.
• Channel Turn-On Time: Requires up to one module update time plus module calibration time.
• Channel Turn-Off Time: Requires up to one module update time.
• Reconfiguration Time: Requires up to one module update time plus module calibration time.
• Channel Scan Time (with lead resistance):
  • 28 Hz = 250 ms
  • 50/60 Hz = 147 ms
  • 800 Hz = 18 ms
  • 6400 Hz = 10 ms
• Channel Scan Time (without lead resistance):
  • 28 Hz = 125 ms
  • 50/60 Hz = 75 ms
  • 800 Hz = 10 ms
  • 6400 Hz = 6 ms
• RTD Excitation Current:
  • RTD setting:
    • 0.25 mA - Recommended for use with higher resistance ranges for both RTDs and direct resistance inputs (1000Ω RTDs and 3000Ω resistance input). Refer to RTD manufacturer for recommendations.
    • 1.0 mA - Recommended to use for all other RTD and direct resistance inputs, except 1000Ω RTDs and 3000Ω resistance input ranges are limited. Refer to RTD manufacturer for recommendations.