Allen-Bradley 1769-PB4 CompactLogix Power Supply Module

Configured for DC backplane power distribution in CompactLogix and MicroLogix 1500 systems, the Allen-Bradley 1769-PB4 (1769-PB4 Power Supply Module) provides direct physical/electrical execution. This expansion power supply connects directly to the 1769 I/O bus structure to deliver regulated 5 VDC and 24 VDC rails to adjacent input, output, and specialty modules.

Hardware Specifications

Backplane Bus Communication Velocity & Power Distribution

The module mounts on the 1769 backplane bus to distribute regulated DC current without interfering with high-speed deterministic communications across adjacent I/O modules. The internal transformer step-down circuitry maintains backplane voltage stability across a power supply distance rating of 8 modules in either direction. Integrated overcurrent and surge protection circuits safeguard connected channel electronics from field voltage transients while firmware flash compatibility across CompactLogix controllers ensures consistent diagnostic monitoring of backplane power rails.

Frequently Asked Questions

Q: What is the maximum number of I/O modules that a single 1769-PB4 power supply can support?

A: A single module has a power supply distance rating of 8, meaning no module can be mounted more than 8 bank positions away from the power supply. Total module count also depends on the combined 5 VDC and 24 VDC backplane current draw.

Q: Can the 1769-PB4 power supply be mounted in a remote bank away from the main controller?

A: Yes, it can power expansion I/O banks connected via 1769 bus expansion cables, provided total backplane current draw remains within 4.0 A at 5 VDC and 2.0 A at 24 VDC.

Q: Does the 1769-PB4 support hot-swapping under backplane power?

A: No, field power and backplane supply lines must be disconnected before removing or inserting the module to prevent electrical arcing and logic corruption.

Field Installation Guidelines

Mount the module on a standard 35 mm DIN rail or secure it directly to an enclosure panel using M4 screws. Maintain at least 50 mm of clear space above and below the housing to allow passive convection cooling across the heat dissipation vents. Connect incoming field power to the front terminal block using copper conductors rated for at least 75 deg C, ensuring input voltage stays within 19.2 to 31.2 VDC. Route field wiring away from high-voltage AC lines and variable frequency drive outputs to minimize electromagnetic interference. Terminate ground wiring directly to the central protective earth ground bus using standard low-impedance grounding strap practices.