Allen-Bradley 1746-OB8 SLC 500 Output Module | 8-Channel, 120V AC, 6A, 8 Points/Common Specs

Allen-Bradley 1746-OB8 SLC 500 Output Module | 8-Channel, 120V AC, 6A, 8 Points/Common Specs

Allen-Bradley 1746-OB8 SLC 500 digital output module specifications. 8-channel 120V AC output, 6A per point, 8 points/common, IP20 protection. For industrial automation and control.

Product Overview

The Allen-Bradley 1746-OB8​ is an 8-channel 120V AC digital output module​ from the SLC 500 series, designed for industrial automation and control applications. This module provides 8 AC output channels​ capable of switching 120V AC loads at 6A per point, organized in one group of 8 points with a common connection. The "1746" designation indicates the SLC 500 I/O module series, "OB8" specifies the 8-channel AC output configuration. This module interfaces SLC 500 controllers to AC field devices such as contactors, solenoids, heaters, and indicators, providing reliable output switching for machine control, process automation, and manufacturing systems.

Technical Specifications

Note: Specifications are based on Allen-Bradley 1746 series technical documentation. The "1746-OB8" model specifically indicates 8-channel 120V AC output configuration. Actual specifications may vary slightly depending on production batch.

Model Number Decoding (1746-OB8)

• 1746:​ Series designation (SLC 500 I/O module series 1746)

• OB8:​ Module type (OB = AC output, 8 = 8 channels)

Note:​ The "OB" prefix indicates AC output functionality. The "8" suffix specifies 8 output channels. This module uses triac (solid-state) switching technology. It is designed for use in SLC 500 chassis (1746-A4, A7, A10, A13) and requires an SLC 500 processor for operation.

Key Features

• 8 AC Output Channels:​ Controls 8 discrete 120V AC output loads

• High Current Capacity:​ 6A per point switching capability

• Internal Fusing:​ Individual 8A fuse protection for each output

• Status Indicators:​ Individual LED indicators for each output point and fuse status

• Removable Terminals:​ Screw terminal blocks for easy wiring and maintenance

• Single Common:​ One common connection for all 8 outputs

• Industrial Grade:​ Designed for harsh industrial environments

• High Isolation:​ 1500V AC isolation between field and logic circuits

• Compact Design:​ Single-slot module for space-efficient installation

• SLC 500 Compatibility:​ Direct integration with SLC 500 controller systems

• Solid-State Reliability:​ Triac switching for long life and fast response

Output Characteristics

Typical Applications

• Machine Control:​ Contactor and starter coil control

• Process Automation:​ Solenoid valve and actuator control

• Material Handling:​ Conveyor motor control and diverter actuation

• Packaging Machinery:​ Heater, sealer, and glue valve control

• HVAC Control:​ Fan, pump, and damper motor control

• Building Automation:​ Lighting control and equipment sequencing

• Water/Wastewater:​ Pump control and valve actuation

• Automotive Manufacturing:​ Production line equipment control

• Heating Control:​ Resistance heater control

• Indicator Lights:​ Pilot light and annunciator control

Important Technical Notes

1. System Requirements:​ Requires SLC 500 chassis (1746-A4, A7, A10, A13) and SLC 500 processor. Not compatible with CompactLogix or ControlLogix systems.

2. Load Ratings:​ 6A rating is for resistive loads. Derate for inductive loads: 3A for 0.5 PF inductive, 1.5A for motor starting.

3. Inductive Load Suppression:​ Use appropriate suppression (RC snubbers or varistors) for inductive loads to protect triacs and reduce EMI.

4. Common Connection:​ All outputs share a common connection. Ensure proper wiring of common to AC neutral.

5. Fusing:​ Each output has internal 8A fuse. Additional external fusing may be required as per local electrical codes.

6. Leakage Current:​ 3 mA maximum leakage current in off-state. This may cause some loads to remain partially energized.

7. Heat Dissipation:​ Maximum power dissipation is 9.6W. Ensure adequate ventilation and ambient temperature within specified range.

8. Wiring:​ Use proper wire size (12-24 AWG) and follow NEC/IEC standards. Separate high-voltage and control wiring.

9. Environmental Conditions:​ Install in appropriate enclosure for protection against dust, moisture, and contaminants. IP20 provides limited protection.

10. Maintenance:​ Periodically check connections, LED status, and output operation. Monitor for proper heat dissipation.

Note: For complete installation guidelines, wiring diagrams, configuration instructions, and detailed technical data, consult the official Allen-Bradley 1746 Series Technical Manual. Always verify the exact model number configuration with the manufacturer, as notation variations may occur.