Overview
The Allen-Bradley 1771-OAD is a PLC-5 discrete AC output module purpose-built for industrial automation applications requiring reliable switching of moderate-voltage AC loads. This 16-point module provides individually controlled output channels capable of driving contactors, solenoids, motor starters, and indicator lamps with voltage ranges from 10 to 138V AC at 47–63 Hz frequency.
Key Features
- Zero-Crossing Switching: Minimizes electrical stress on connected loads and extends component life by switching only when the AC voltage crosses zero.
- 16 Programmable Output Channels: Each output independently controlled, with dual-level status indication for operational diagnostics.
- Wide Operating Voltage Range: Supports 10–138V AC at 47–63 Hz, allowing flexible load compatibility.
- Compact Rack-Mount Form Factor: Installs directly into 1771 I/O chassis backplane with screw-terminal connections.
- Low Backplane Current Demand: Requires only 295mA from the chassis 5V supply, minimizing backplane loading.
Technical Specifications
- Output voltage range: 10–138V AC @ 47–63 Hz
- Output current rating: 2A per output, maximum 8A per module
- Number of outputs: 16
- Surge current (max): 25A per output for 100ms, repeatable every 1 second
- Minimum load current: 5mA; maximum OFF-state leakage: 3.0mA @ 138V AC
- Power dissipation: 13W maximum, 1.5W minimum
- Backplane current: 295mA @ 5VDC
- Mounting: Rack-mount (1771 chassis compatible)
- Terminal style: Screw terminals
- Operating temperature: Up to 140°F (60°C)
- Weight: 2.09–2.23 lbs
- Certifications: UL, CE, CSA, C-TICK, GOST, MARINE
- Status: Discontinued by Rockwell Automation as of December 31, 2016
Typical Applications
- Solenoid valve and motor starter control
- Industrial lighting and alarm output control
- HVAC and facility automation systems
- Conveyor and material-handling equipment
- Legacy PLC-5 system retrofits and repairs
Compatibility & Replacements
The 1771-OAD is compatible with 1771-A1B through A4B, 1771-AM1, and 1771-AM2 chassis, and is NOT compatible with early 1771-A1, 1771-A2, and 1771-A4 models. Series variants (1771-OAD/A, /B, /C, /D) may have minor specification or configuration differences; verify part revision before installation. When connecting to input modules, a 39kΩ, 1W shunt resistor may be required across loads with diode suppression to ensure proper operation. Related modules in the 1771 series include 1771-OA (12V only), 1771-OD (isolated AC), and 1771-ON (general AC output). Since discontinuation in 2016, replacements are limited; consult Rockwell Automation or authorized resellers for modern CompactLogix or ControlLogix equivalent modules if new units are required.
