I/O modules

Product Overview

The Allen-Bradley 1797-TB3 FLEX Ex Terminal Base Unit is designed for use in hazardous area applications within the FLEX Ex I/O system. With 36 wiring connections, it provides secure and intrinsically safe connectivity for plug-in I/O modules. The terminal base features an integrated Flexbus connector for module-to-module communication, ensuring safe and reliable operation in process automation environments.

The 1797-TB3 is designed for screw terminal connections, while the 1797-TB3S variant uses spring-clamp terminals. Both support intrinsically safe installations, making them ideal for industries such as oil & gas, chemical processing, and other hazardous applications.

Key Features

• 36 terminal points for field wiring connections.
• Supports intrinsically safe circuits for hazardous locations.
• Compatible with FLEX Ex I/O modules for safe and flexible expansion.
• Factory-installed Flexbus tab cover for backplane connection.
• Available in screw terminal (1797-TB3) or spring-clamp (1797-TB3S) versions.
• Designed and certified for hazardous area use with multiple global approvals.

Technical Specifications

Terminal Base Connections

• Number of Terminals: 1 row of 16, 2 rows of 18
• 1797-TB3 Terminal Screw Torque: 0.8…1.0 Nm (7…9 lb-in)
• 1797-TB3S Terminal Type: Spring-clamp
• Wire Size: 4 mm² (12 AWG) stranded max.
• Insulation: 1.2 mm (3/64 in.) max.

Terminal Assignments

• Specific Terminals: +34, -35, +50, -51, 96
• Female I/O Connector Pins: 30…32, 62…64, 94…96, 36, 49
• All Other Terminals: Intrinsically safe circuits only
• Flexbus Connection (Intrinsically Safe): Ui < 10V DC, Ii < 400 mA, Ci < 1 nF, Li negligible

Electrical Ratings

• Ui (Input Voltage): <10V DC for intrinsically safe terminals
• Ii (Input Current): <2.5 A for terminals, <400 mA for Flexbus
• Isolation Voltage: Channel-to-channel isolation depends on the installed I/O module

Physical Specifications

• Weight: Approx. 200 g
• Dimensions (with module installed):
  • Metric: 94H x 94W x 69D mm
  • Imperial: 3.7 x 3.7 x 2.7 in.

Environmental Conditions

• Operating Temperature: -20…70°C (-4…158°F)
• Storage Temperature: -40…85°C (-40…185°F)
• Relative Humidity: 5–95%, non-condensing
• Shock: 15 g, 11 ms pulse (operating & non-operating)
• Vibration: 2 g, 10–500 Hz (IEC 68-2-6)

Certifications

• IECEx: Ex ia IIC T4 Gb
• CENELEC (ATEX): II 2G Ex ia IIC Gb T4
• UL / cUL: Class I, Div 1, Groups A–D; Class II, Groups E–G; Class III Hazardous Locations
• FM: Intrinsically Safe, Associated Apparatus approval
• INMETRO: BR-Ex ia IIC T4
• Certificates: IECEx BVS 08.0006X, CENELEC DMT 98 ATEX E012 U, UL File E197983, FM 3009806, INMETRO 05/UL-BRAE-0019U

⚠️ Note: Terminal connections vary with each I/O module. Always refer to the module’s installation instructions for wiring details.

Applications

The Allen-Bradley 1797-TB3 FLEX Ex Terminal Base Unit is widely used in industries requiring intrinsically safe I/O integration, such as:

• Oil & gas exploration and refining
• Petrochemical and chemical processing
• Pharmaceutical manufacturing
• Hazardous area automation systems

Details