Allen-Bradley 1771-PA Auxiliary Power Supply

The Allen-Bradley 1771-PA Auxiliary Power Supply is a Bulletin 1771 module designed to power PLC‑5 1771 I/O racks by delivering a dedicated fixed low-voltage supply to the backplane. It accepts 120/240 VAC input at 50/60 Hz and provides a 5.1 V DC output with a current rating up to 0.5 A, enabling stable operation of the connected 1771 I/O modules. As an integral part of the PLC‑5 1771 I/O family, this standalone power supply is used to energize the I/O chassis without relying on the processor’s primary supply, making it a common choice for rack expansions, replacements, or refurbishment of legacy PLC systems. The 1771-PA is cataloged for use with Bulletin 1771 components and is specifically associated with the PLC‑5 1771 I/O architecture, ensuring compatibility with the 1771 power distribution scheme and backplane interfaces.