1769-PB4 | Allen-Bradley Compact I/O 24V DC Expansion Power Supply

Product Overview

The 1769-PB4 is a high-capacity DC power supply module engineered for the Allen-Bradley CompactLogix and MicroLogix 1500 systems. It provides the necessary backplane current to support downstream I/O modules when the controller's integrated power capacity is exceeded. This module is essential for expanding the architecture of a 1769-based system, ensuring stable voltage and current distribution across the communication bus. Its robust design features reinforced insulation and integrated fuse protection, making it suitable for rigorous industrial automation environments where reliable 24V DC power is a prerequisite.

Technical Specifications

• Manufacturer: Allen-Bradley / Rockwell Automation

• Model Number: 1769-PB4

• Power Supply Type: 24V DC Input Expansion Supply

• Input Voltage Range: 19.2V to 31.2V DC

• Power Consumption: 100 VA @ 24V DC

• Inrush Current: 30A maximum @ 31.2V DC

• Output Current Capacity: 4.0A @ 5V DC; 2.0A @ 24V DC

• Module Distance Rating: Supports up to 8 I/O modules on either side (16 total)

• Isolation Voltage: 75V continuous (Tested at 1697V DC for 1 second)

• Power Dissipation: 14.5 Watts @ 60°C

• Internal Protection: Wickmann 19193-6.3A or Littelfuse 021706.3MXP fuse

• Mounting Options: 35mm DIN rail or direct panel mount

• Dimensions: 11.8 x 7.0 x 8.7 cm

• Weight: 0.91 kg (2.0 lbs)

Operational Implementation

The 1769-PB4 acts as a central power hub within a Compact I/O bank. Because 1769 modules have a specific distance rating, this power supply allows engineers to extend the physical length of the I/O assembly by injecting fresh power into the backplane. It is commonly used in distributed control panels where the primary 24V DC source is shared among various components. The module’s status is easily monitored via front-panel LED indicators, and its fanless convection cooling design ensures long-term durability in enclosures with high component density.

Frequently Asked Questions

Does the 1769-PB4 provide power to field-side devices?No, the 1769-PB4 is designed specifically to provide logic-side power to the modules via the backplane bus. Field-side actuators and sensors typically require a separate external 24V DC power source wired directly to the I/O module terminal blocks.

Can I use multiple 1769-PB4 modules in a single I/O bank?Yes, in complex systems where the total current draw of the I/O modules exceeds the capacity of a single supply, additional 1769-PB4 units can be installed. However, you must adhere to the distance rating and ensure that the backplane is logically segmented as per Rockwell Automation's installation guidelines.