Allen-Bradley 1797-IE8NF Flex Ex Analog Input Module

Configured for high-precision signal acquisition in hazardous environments, the Allen-Bradley 1797-IE8NF (1797-IE8NF Flex Ex Analog Input Module) provides direct physical and electrical execution of 8-channel analog sensing with integrated noise filtering for Flex I/O 1797 platforms.

Hardware Specifications

Intrinsic Safety (Ex i) Barriers and Connectivity

The 1797-IE8NF serves as a dedicated Ex ib IIC T4 rated module for applications requiring intrinsic safety. The internal circuit design incorporates mandatory isolation properties required for Class I, II, and III Division 1 & 2 hazardous area installations. Proper integration demands the use of the 1797-TB3 or 1797-TB3S terminal bases, with the keyswitch positioned at 3 to ensure mechanical compatibility. The integrated noise filter stabilizes the input signal against high-frequency interference, maintaining the integrity of the 16-bit resolution across the entire input range.

Frequently Asked Questions

Q: Are the eight input channels electrically isolated from each other?

A: No. The 1797-IE8NF features eight single-ended, non-isolated inputs. Common-mode voltage constraints must be observed to prevent measurement errors or damage to the input stage.

Q: Can this module be installed in a standard (non-hazardous) area?

A: While the module is designed for hazardous environments (Ex i), it may be installed in non-hazardous locations provided that the electrical installation complies with relevant codes for the Flex Ex system architecture and that the module is correctly interfaced with the Flex Ex terminal base.

Field Installation Guidelines

• Terminal Base Assembly: Mount the 1797-TB3 or 1797-TB3S terminal base before installing the module. Verify the keyswitch is set to position 3; failure to align the keyswitch will prevent the module from seating correctly.
• Wiring Specifications: Utilize stranded conductor wire up to 4 mm2 (12 gauge). Ensure the insulation diameter does not exceed 1.2 mm to maintain the integrity of the terminal connections within the hazardous area rating requirements.
• Shielding and Grounding: Given the non-isolated nature of the inputs, connect cable shields to the designated chassis ground point on the terminal base to mitigate external noise. Ensure the entire Flex Ex rack is securely bonded to the main earth ground to comply with intrinsic safety grounding practices.
• Environmental Considerations: The 1797-IE8NF produces 5.2 W of power dissipation (17.75 BTU/hour). Ensure sufficient ventilation in the enclosure to maintain the ambient temperature within the specified range, especially when multiple modules are mounted in a single rack.