Order now the 1794-TB3G, a specialized 3-wire grounded terminal base unit for the Allen-Bradley FLEX I/O system. This module is engineered to provide superior grounding capabilities, making it the ideal choice for analog I/O modules and sensitive digital signals that require a direct path to functional earth.
What Is the 1794-TB3G?
The 1794-TB3G is a terminal base that expands on the capabilities of the standard TB3 by adding a dedicated ground bus. It features 36 terminals total: 16 I/O terminals, 16 power terminals, and 4 specialized ground terminals. The «G» variant is essential for analog applications where cable shields must be terminated correctly to minimize electromagnetic interference (EMI). The base provides the mechanical and electrical interface for FLEX I/O modules, allowing them to communicate via the FlexBus while keeping field wiring organized. Like other units in the series, it supports RIUP, allowing module replacement without powering down the entire station, which is vital for process industry continuity.
Key Technical Specifications
- Terminal Type: Screw-clamp
- Number of Terminals: 36 (16 I/O, 16 Power, 4 Ground)
- Current Capacity: 10A maximum
- Voltage Rating: 125V AC/DC
- FlexBus Current: 640mA
- Grounding: Internal ground bus connected to DIN rail
- Wire Size: 0.34 to 2.5 mm² (22 to 12 AWG)
Industrial Grounding Architecture
The 1794-TB3G simplifies the grounding scheme of an industrial control panel. By providing internal connections between the ground terminals and the DIN rail, it ensures a low-impedance path for noise currents. This is particularly critical when using high-resolution analog modules (like the 1794-IF8IH) or when the I/O is located near variable frequency drives (VFDs) or other noise-generating equipment. The base ensures that the system stays compliant with EMC regulations without excessive external terminal blocks.
Maintenance Tips
For the 1794-TB3G to provide effective grounding, the DIN rail must be clean, unpainted, and properly connected to the building’s earth ground. Periodically check for oxidation on the DIN rail contact surface. If signal noise increases in your analog loops, verify that the cable shields are securely fastened to the G terminals on this base and not «pigtail» grounded at multiple points, which can create ground loops.
Frequently Asked Questions
Q: Is the 1794-TB3G required for all analog modules?
A: While not strictly mandatory for all, it is highly recommended for any analog module involving shielded cables to provide the cleanest possible signal path.
Q: Can I use this base with a 1794-IB16 digital module?
A: Yes, it is fully compatible with 16-point digital modules. The additional ground terminals can be used as common points for sensor shielding if needed.
Do you need more references from this brand? Explore our full catalog of Allen-Bradley here: https://atlantechdrives.com/manufacturers/allen-bradley/
