Product Overview
The Allen-Bradley 1794-TB3G belongs to the Flex I/O 1794 series terminal base family. This unit hosts Flex I/O modules and provides field wiring connections. It connects I/O modules to the I/O bus through the terminal base. The 1794-TB3G uses grounded screw clamp terminals for reliable connections. Panel builders and system integrators use this base for distributed I/O applications.
Technical Specifications
The 1794-TB3G has a voltage rating of 24V DC/AC. Its maximum supply voltage is 31.2V DC/AC at 50/60 Hz. Maximum supply current rating is 10A.
Terminal and wiring details:
Terminal screw torque: 0.56 to 0.79 Nm (5 to 7 lb-in)
Wire size: 0.21 to 1.3 mm² (24 to 16 AWG)
Wire type: Stranded copper only
Wire insulation rating: 75 °C (167 °F) minimum
Maximum insulation thickness: 1.2 mm (3/64 inch)
Terminal point configuration:
Maximum I/O terminal points: 36
Common terminals: 2
Positive voltage terminals: 2
Chassis ground terminals: 10
Bus and isolation ratings:
FlexBus current: 640 mA at 5V DC
Maximum I/O terminal current: 2A
Voltage/communication terminal rating: 125V DC/AC at 10A, 50-60 Hz
Maximum continuous isolation voltage: 50V
Isolation tested at: 2121V DC for 60 seconds (field wiring to FlexBus)
Insulation type: Basic Insulation Type
Environmental Specifications
The 1794-TB3G operates without de-rating across a wide temperature range. It carries T4A and IEC TA temperature codes.
Temperature limits:
Humidity and mechanical ratings:
Relative humidity: 5 to 95% non-condensing (operation and storage)
Operating shock: 30 G
Operating vibration: 5 G at 10 to 500 Hz
The 1794-TB3G maintains all functions at these ratings
Physical Dimensions
The 1794-TB3G has compact dimensions for panel installation:
Width: 94 mm (3.7 inches)
Height: 94 mm (3.7 inches)
Depth: 69 mm (2.7 inches)
The terminal base weighs approximately 0.25 kg
Module Compatibility
The 1794-TB3G is specifically designed for the 1794-VHSC very high speed counter module. This terminal base provides the special termination required for high speed signals. Other Flex I/O modules may not work correctly with this base. Always verify module compatibility before installation.
Keyswitch Setting
The 1794-TB3G uses a specific keyswitch position. Set the keyswitch to match the installed I/O module. Proper keying prevents incorrect module insertion. This mechanical protection avoids damage to both the base and the module.
Installation Guidelines
Mount the 1794-TB3G on a standard DIN rail or directly on a panel. Use 0.56 to 0.79 Nm torque for all terminal screws. Strip wires to the appropriate length before insertion. Do not exceed 10A total current through any terminal. Keep field wiring separate from high voltage cables.
Ground the 1794-TB3G properly using the chassis ground terminals. Use a zinc-plated DIN rail for reliable grounding. Connect the external power supply to the positive voltage terminals. The 1794-TB3G supports hot insertion of compatible I/O modules.
Package Contents
One Allen-Bradley 1794-TB3G Flex I/O Terminal Base Unit
One keyswitch (factory installed)
Mounting instructions sheet
Frequently Asked Questions (FAQ)
1. Which Flex I/O modules work with the 1794-TB3G?
The 1794-TB3G is designed for the 1794-VHSC very high speed counter module. Always check compatibility before installation.
2. What is the maximum current rating for this terminal base?
The 1794-TB3G handles up to 10A supply current. Maximum I/O terminal current is 2A per point.
3. What wire size does the 1794-TB3G accept?
The 1794-TB3G accepts 0.21 to 1.3 mm² (24 to 16 AWG) stranded copper wire. Use wire rated for 75°C minimum.
4. Can I mount the 1794-TB3G on a panel instead of DIN rail?
Yes, the 1794-TB3G supports both DIN rail and panel mounting. Follow the torque specifications for mounting screws.
5. What is the operating temperature range of the 1794-TB3G?
The 1794-TB3G operates from -20 to 70 °C (-4 to 158 °F). Storage temperature ranges from -40 to 85°C.
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