Allen-Bradley 1746-OB32 SLC 500 Output Module Overview

The Allen-Bradley 1746-OB32 is a SLC 500 digital DC output module. This module features thirty-two (32) output channels arranged in two (2) groups of sixteen points each. The nominal output voltage is 24 VDC with a wider operating range of 5 to 50 VDC. The 1746-OB32 uses a sourcing output configuration, meaning it supplies voltage to the load. This module may be installed in any SLC 500 fixed or modular style hardware. However, it cannot be installed in slot 0 of the 1746 chassis.

Output Current & Power Specifications

The Allen-Bradley 1746-OB32 provides substantial output current for various loads. Continuous current per output point is 0.5 A at 30°C . At 60°C, the per-point rating derates to 0.25 A . Continuous current per module reaches 8.0 A total . Current per common (group of 16 points) is 2.0 A . Surge current per point is 1.0 A for 1 ms , repeatable every 2 seconds. Minimum load current required is 1 mA per output channel. Therefore, the 1746-OB32 handles most DC loads including solenoids, relays, and indicator lights.

Electrical & Timing Specifications

The Allen-Bradley 1746-OB32 offers reliable electrical performance for industrial applications. Backplane current consumption is 190 mA at 5 VDC . Output circuit isolation is tested at 1500 V AC for 1 minute . Signal delay for ON transitions is 0.1 ms maximum . Signal delay for OFF transitions is 1.0 ms maximum . Maximum off-state leakage current is 1 mA . On-state voltage drop is 1.2 V at 0.5 A . Power dissipation is 0.172 W per point , with total module heat dissipation of 6.45 W . Consequently, the 1746-OB32 provides fast switching with minimal power loss.

Interposing & Isolation Applications

The Allen-Bradley 1746-OB32 may be used with interposing relays for AC loads. If output devices operate on AC voltage, a relay with a 24 VDC coil serves as the load. The relay's Normally Open (N.O.) or Normally Closed (N.C.) contacts then switch the AC voltage. In older wired systems where electrical noise is present, interposing also provides external module isolation. Therefore, this protects the 1746-OB32 from external damage or unwanted behavior. Poor grounding and undocumented wiring modifications in old systems can cause issues that interposing helps prevent.

Environmental & Certification Specifications

The Allen-Bradley 1746-OB32 operates reliably in demanding industrial environments. Operating temperature range spans 0°C to +60°C (+32°F to +140°F) . Relative humidity tolerance reaches 5% to 95% non-condensing . Operating shock tolerance is 30G . Operating vibration tolerance is 2.5G at 10-200 Hz . Agency certifications include C-UL and UL Listed Industrial Control Equipment . Hazardous location approval includes Class I, Division 2, Groups A, B, C, D . Additionally, the 1746-OB32 meets NEMA standard ICS 2-230 Noise immunity .

Terminal Block & Wiring Options

The Allen-Bradley 1746-OB32 ships with a Removable Terminal Block (RTB) . An octal door label and 32 LED lights (one per channel) are also included. A color-coded module bar displays the part number for easy identification. Allen-Bradley 1746-N3 or 1492 wiring systems are compatible with this module. These connector systems ensure proper termination and adequate wire size. Pre-assembled systems also prevent improper wiring and allow the module door to close fully. Other wires may be used, but large wire sizes will over-occupy the front panel. Consequently, troubleshooting becomes difficult and the module door may not close properly.

Key Features & Benefits

• 32 sourcing outputs – The 1746-OB32 provides high-density DC output control.

• Two isolated groups – Sixteen points per common for flexible load distribution.

• Wide voltage range – Operates from 5 to 50 VDC for application flexibility.

• Fast response time – 0.1 ms ON delay for time-critical applications.

• High noise immunity – Meets NEMA ICS 2-230 standards.

• Hazardous location approved – Class I, Division 2 certified.

• Removable terminal block – Simplifies wiring and maintenance.

Installation Guidelines

Follow these steps to install the Allen-Bradley 1746-OB32 correctly. First, power down the SLC 500 chassis completely. Second, select an available slot for the module (not slot 0). Third, align the 1746-OB32 with the card guides in the chassis. Fourth, push the module firmly into the backplane connector until fully seated. Fifth, secure the module with the retaining screws at top and bottom. Finally, wire field devices to the removable terminal block before re-inserting it into the module.

Observe derating guidelines when operating at temperatures above 30°C. For 60°C ambient, reduce per-point current to 0.25 A. Ensure total module current does not exceed 8.0 A. The 1746-OB32 uses a sourcing output configuration. Therefore, the load connects between the output terminal and the DC common.

Package Contents

Your shipment includes the following items:

• 1 x Allen-Bradley 1746-OB32 digital DC output module

• 1 x Removable Terminal Block (RTB) (pre-installed on module)

• 1 x Octal door label for channel identification

• 1 x Installation instructions manual

No wiring or external power supply is included with the 1746-OB32. Therefore, you must provide suitable DC power and field wiring separately.

Frequently Asked Questions (FAQ)

1. What is the difference between sourcing and sinking outputs?
The Allen-Bradley 1746-OB32 is a sourcing output module. Therefore, it supplies positive voltage to the load. The load connects between the output terminal and the DC common.

2. Can I use this module with 120 VAC loads?
Not directly. The 1746-OB32 provides DC output only. However, you can use an interposing relay with a 24 VDC coil to switch 120 VAC loads.

3. What is the per-common current rating?
The 1746-OB32 has 16 points per common. Each common (group) can carry up to 2.0 A total. Therefore, distribute loads across both groups to stay within limits.

4. Does this module have electronic protection?
No. The 1746-OB32 does not have electronic protection. External fusing is recommended for each output or each common.

5. Is this module approved for hazardous locations?
Yes. The Allen-Bradley 1746-OB32 is UL/C-UL listed for Class I, Division 2, Groups A, B, C, D. Therefore, it is suitable for use in hazardous areas.

Why Choose the Allen-Bradley 1746-OB32?

This SLC 500 digital output module delivers reliable control for DC loads in industrial applications. For starters, the Allen-Bradley 1746-OB32 provides 32 sourcing outputs in two groups of 16 channels each. The wide voltage range from 5 to 50 VDC accommodates various DC power systems. Each output handles 0.5 A continuously at 30°C, with 1.0 A surge capability for 1 ms. Fast switching times of 0.1 ms ON and 1.0 ms OFF suit time-critical applications. The removable terminal block simplifies installation and maintenance. Backplane current draw is only 190 mA at 5 VDC. Derating guidelines at 60°C (0.25 A per point, 8.0 A per module) provide safe operation in warm environments. The 1746-OB32 is ideally suited for pilot lights, buzzers, horns, solenoids, and interposing relays. Hazardous location certification (Class I, Division 2) expands installation options. Most importantly, this module integrates seamlessly into any SLC 500 system.

Order the Allen-Bradley 1746-OB32 today for your discrete output needs. Specifically, this module is perfect for machine control, conveyor systems, packaging equipment, and other applications requiring high-density DC sourcing outputs in a SLC 500 platform.