Product Summary
The Allen-Bradley 1794-OA8I Flex I/O module provides eight isolated 120V AC digital outputs for industrial control systems. It switches actuators based on PLC logic and delivers up to 500 mA per channel for demanding applications.
Expert Technical Evaluation & Performance Review
Robust Output Stage with Individual Isolation
The 1794-OA8I module drives eight isolated outputs with a nominal voltage of 120V AC. Each channel supports a continuous current rating of 4.0A total, translating to 500 mA per output. This design ensures reliable switching for solenoid valves and motor starters.
Superior Electrical Protection Specifications
This module provides an on-state voltage drop of just 1.0V at 0.5A maximum. The off-state leakage current measures only 2.25mA maximum. These values guarantee efficient power delivery and prevent false triggering of connected loads.
High Isolation Voltage for System Safety
The 1794-OA8I maintains 120V continuous isolation between channels and the backplane. It also withstands 1250V AC for 60 seconds between channels. This robust isolation protects sensitive controller electronics from field-side transients.
Thermal Management and Power Budgeting
This module dissipates only 4.1W of power at 0.5A output current. It draws just 80mA from the 5V DC FlexBus. This low thermal dissipation, rated at 14.0 BTU/hr, allows dense installation within control cabinets.
Operational Environment and Physical Dimensions
You can install this module in ambient temperatures ranging from -20 to 55 degrees Celsius. Its compact form factor measures 94mm by 94mm by 69mm. This small footprint saves valuable space on the DIN rail.
Step-by-Step User & Installation Guide
Selecting the Correct Terminal Base
You must install the 1794-OA8I into a compatible terminal base with its keyswitch set to Position 8. Compatible bases include the 1794-TB3S, 1794-TB2, and 1794-TB3. These units provide the necessary screw-clamp connections for field wiring.
Wiring the Isolated Output Channels
Connect each isolated output to an even-numbered terminal on the base. Connect the 120V AC power supply to the adjacent odd-numbered terminal. You must wire each device's common terminal appropriately for proper circuit completion.
Mechanical Mounting on DIN Rail
Hook the terminal base over the top of the DIN rail at a slight angle. Slide the base tight against the adjacent adapter module to engage the FlexBus connector. Push the base downward until it locks securely onto the rail.
Applying Recommended External Fusing
You must use a 1.6 Amp, 250V AC slow-blow fuse for each output circuit. This fuse protects the module's internal components from overcurrent conditions. Never exceed the maximum current rating of 4.0A total across all channels.
Verifying Output Status via LED Indicators
Each output channel has a yellow LED indicator on the module's field side. This LED illuminates when the output is in the active or "on" state. Use these indicators for quick visual troubleshooting during system commissioning.
Logistics & Standard Packaging Details
- One (1) Allen-Bradley 1794-OA8I Flex I/O Digital Output Module
- Manufacturer: Rockwell Automation
- Brand: Allen-Bradley
- Part Number: 1794-OA8I
- Shipping is available via FedEx, UPS, and DHL for express delivery.
