Product Overview
The Allen-Bradley 1794-OW8 is a Flex I/O relay output module from Rockwell Automation. It provides eight isolated normally open (Form A) electromechanical relays for switching AC or DC loads. This module is designed for use in distributed control systems where reliable output switching is required. Its isolated channels help prevent cross-channel interference, making it suitable for applications needing signal integrity.
Technical Specifications Breakdown
Key parameters for the 1794-OW8 are listed below for quick reference:
| Feature | Specification |
|---|---|
| Output Type | Relay Output |
| Number of Outputs | 8, Isolated |
| Relay Contact Rating | 250V AC, 2 A, 50/60Hz, Resistive; 120/240V AC, 50/60Hz, 1800V A Make, 180V A Break; 5…30V DC, 2 A, Resistive |
| Supply Voltage | 24V DC, 125 mA |
| Flexbus Current | 5V DC, 35 mA |
| Operating Temperature | 0 to 55 °C (32 to 131 °F) |
| Storage Temperature | -40 to 85 °C (-40 to 185 °F) |
| Power Dissipation | 5.5 Watts |
| Thermal Dissipation | 18.8 BTU/hour at maximum |
Industry Applications
This relay output module is commonly used in manufacturing lines for switching motors, solenoids, and indicator lights. The isolated outputs ensure that a fault on one channel does not affect others, reducing downtime. In process control, the 1794-OW8 can drive alarms or actuators in environments where AC loads are prevalent. Its 250V AC rating makes it suitable for European and North American industrial voltages.
Installation & Setup Guidance
Mount the module on a DIN rail using the keyswitch position 9. Compatible terminal bases include 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TBN, and 1794-TBNF. If using the 1794-TBNF, install a 3.0 Ampere, 250VAC slow-blow fuse (e.g., Littelfuse 239003). Wire the supply voltage at 24V DC, 125 mA, and ensure the external DC supply range is within 19.2 to 31.2 Volts DC. The module draws 35 mA from the FlexBus at 5V DC. Use only +24 Volts DC power for the power terminals to avoid relay timing variations.
Maintenance & Reliability
Inspect the module periodically for signs of overheating or contact wear. The relay contacts have a mechanical life of 100,000 operations at rated loads. Keep the enclosure open-type and ensure ambient temperature stays within 0 to 55 °C. The module withstands vibration up to 5g at 10 to 500 Hz and operating shock up to 30 g. Check the off-state leakage current (1.0 mA through snubber circuit) if used with sensitive loads.
Compatibility & Integration
The 1794-OW8 works with any Flex I/O communication adapter and FlexBus controllers. It is compatible with several terminal base units, including 1794-TB3, 1794-TB2, 1794-TBN, 1794-TB3S, 1794-TB3K, 1794-TBNF, 1794-TBNKF, and 1794-TB3SK. The module has eight yellow status indicators, one per channel, for quick visual diagnostics.
Selection Guide & Purchasing Advice
When selecting the 1794-OW8, verify your system's voltage requirements and load types. For availability and lifecycle status, contact AutoDCSTech. AutoDCSTech offers genuine Allen-Bradley parts and can assist with compatibility checks.
Troubleshooting & Common Issues
If an output fails to switch, check the status indicator and verify the supply voltage. Ensure the load does not exceed the relay contact rating. For intermittent operation, inspect the terminal base wiring and confirm the keyswitch position is correct. If the module does not communicate, verify the FlexBus connection and adapter compatibility.
Availability & Condition at AutoDCSTech
| Part Number | 1794-OW8 |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
