Allen-Bradley 1756-PA75 ControlLogix AC Power Supply Module

Product Overview

The 1756-PA75​ is the standard AC-input power supply for the Rockwell Automation ControlLogix 1756 platform, manufactured under the Allen-Bradley brand. It converts a universal 120/240 V AC mains input into the regulated voltages required by the ControlLogix backplane — primarily 5.1 V DC at up to 13 A — and it does so while drawing less than 1,000 VA from the source. The 1756-PA75​ is a chassis-resident module rather than a standalone bench supply: it mounts in a dedicated power-supply slot at the left of a 1756-A4, A7, A10, A13, or A17 chassis and feeds the backplane directly, so every I/O module, communication module, and controller in that chassis receives its operating power from a single, centrally managed source.

What sets the 1756-PA75​ apart from a generic DC supply is the integration with the ControlLogix system. It monitors its own output, drives the chassis status indicators, and reports its state to the controller through the backplane, which means a failing supply is visible in the I/O tree and in the controller’s system-status logic rather than being discovered only when the chassis goes dead. The 1756-PA75​ also accepts a 19.2 to 31.2 V DC backup input, which is intended for connection to an uninterruptible power supply or a battery-backed DC source. Under normal operation the module runs from the AC line; when mains is lost, the external DC source takes over without interruption to the backplane, giving the application a clean way to ride through brief outages or to execute an orderly, controlled shutdown.

The 1756-PA75R​ is the redundant version of the 1756-PA75. It adds a second, paralleled AC input and a redundant power connector, and it ships with the 1756-CPR2​ redundancy cable so two supplies can be cabled together in the same chassis. When one 1756-PA75R​ fails or is removed, the second continues to power the backplane without a hiccup, and the chassis status logic identifies which unit is at fault. For processes where an unplanned stop costs more than the redundant hardware, the 1756-PA75R​ is the correct specification, and it uses the identical 120/240 V AC input and 18-32 V DC output ratings as the standard unit.

Technical Specifications