Overview
The Allen-Bradley 1746-OA8 is a discrete AC output module designed for the SLC 500 series of programmable logic controllers. This eight-channel output module energizes AC loads operating in the 85–264VAC range at 50/60 Hz, making it suitable for general-purpose industrial automation applications. The module occupies a single I/O slot on any 1746 SLC 500 chassis and integrates seamlessly with existing SLC 500 control systems.
Key Features
- Eight output channels organized in two isolated groups of four channels each for flexible wiring and reduced cross-channel interference
- AC voltage rating: 85–264VAC, 50/60 Hz operation with nominal ratings of 120VAC and 240VAC
- Output current: 1.0 A per channel @ 30°C (86°F) or 0.50 A per channel @ 60°C (140°F); maximum module load 8.0 A @ 30°C or 4.0 A @ 60°C
- Signal switching: 1 ms ON signal delay and 11 ms maximum OFF signal delay for resistive loads
- 1500V AC isolation between field and logic sides for enhanced safety and noise immunity
- LED indicators on each output channel for quick visual status verification
- Removable screw terminal block allows pre-wiring and fast module replacement without disturbing field connections
- Backplane current: 185 mA @ 5VDC
Technical Specifications
- Output Voltage Range: 85–264VAC (47–63 Hz)
- Output Channels: 8 (two isolated groups of 4 each)
- Continuous Output Current per Channel: 1.0 A @ 30°C; 0.50 A @ 60°C
- Maximum Continuous Output Current (Module): 8.0 A @ 30°C; 4.0 A @ 60°C
- Nominal Ratings: 120VAC, 240VAC
- Input Isolation: 1500V AC
- Backplane Current: 185 mA @ 5VDC
- ON Signal Delay: 1 ms (resistive load)
- OFF Signal Delay: 11 ms maximum (resistive load)
- Mounting: Single slot in 1746 SLC 500 chassis
- Terminal Type: Removable screw terminal block
Typical Applications
The 1746-OA8 is ideal for controlling AC loads such as:
- Motor starters and contactors
- Indicator lights and annunciators
- Solenoid valves and air compressors
- Pumps and fans in HVAC systems
- General-purpose AC switching in process control and manufacturing automation
- Legacy SLC 500 system upgrades and expansions
Compatibility & Replacements
Compatible With
- Allen-Bradley SLC 500 modular chassis (1746-A2, 1746-A4, 1746-A13, etc.)
- SLC 500 processors (1747-L511, 1747-L512, 1747-L514, 1747-L523, 1747-L524, 1747-L531, 1747-L532, 1747-L533, 1747-L541, 1747-L542, 1747-L543, 1747-L553)
- RSLogix 500 programming software
- Studio 5000 (with appropriate import/conversion)
- Local area networks (DH-485, ethernet modules)
Replaces / Drop-In Replacement For
The 1746-OA8 Series A is a direct replacement for earlier 1746-OA8 modules and can substitute for systems originally configured with this part number. Always verify I/O addressing and module slot position before installation.
Works With
- RSLogix 500 (SLC 500 programming software)
- Allen-Bradley SLC 500 backplane communication
- Local area networks and remote I/O via optional DH-485 or ethernet interface modules
- Standard 24V DC field wiring for input status monitoring
