Allen-Bradley 1771-P4R Industrial Power Supply

The Allen-Bradley 1771-P4R is a redundant power supply module for Allen-Bradley 1771 I/O racks used in PLC-5 and SLC 500 automation systems. As a redundant (R) unit, it is designed to operate alongside a second power supply to provide dual, fault-tolerant DC power to the 1771 backplane, helping keep critical I/O operational in the event of a single-supply failure. It installs in the standard 1771 I/O chassis and shares the same backplane interface with other 1771 power components, ensuring compatibility within existing 1771-based configurations. Common applications include manufacturing lines, packaging, and process-control cabinets where uninterrupted power to I/O modules and the processor is essential. The P4R is part of Allen-Bradley’s PLC-5/SLC 500 power-supply ecosystem and is typically used in dual-redundant setups alongside related models such as the 1771-P6R. For proper installation and long-term reliability, follow the manufacturer’s recommendations for 1771 power-supply pairing and chassis wiring in industrial automation environments.