Allen‑Bradley 1771‑P6S​ 1771 Series PLC‑5 Rack Power Supply – 220 VAC Input, 5 VDC @ 8 A Backplane Output

Product Overview

The Allen‑Bradley 1771‑P6S​ is a chassis‑mounting AC input power supply module developed for Rockwell Automation’s 1771 I/O platform, most commonly used to power PLC‑5 processor racks and standalone 1771 I/O expansion frames. Designed to occupy the dedicated leftmost power slot (Slot 0) of any 1771 rack—including the 1771‑A1B (4‑slot), 1771‑A2B (8‑slot), 1771‑A3B (12‑slot), and 1771‑A4B (16‑slot) chassis—the 1771‑P6S​ converts a 194–264 VAC single‑phase mains supply into a tightly regulated 5.06 VDC at up to 8.0 A for the 1771 backplane bus, which in turn powers the processor (if present), all installed I/O modules, and communication adapters in that rack. This 8 A capacity is sufficient to drive a fully populated 8‑ or 16‑slot 1771 I/O rack containing a mixture of digital input/output and analog modules, subject to the individual module current draw specifications documented in Rockwell’s 1771 module datasheets.The Allen‑Bradley 1771‑P6S​ features galvanic isolation of 2500 VDC for 1 second between AC input and the low‑voltage DC outputs, overload and over‑voltage protection with automatic shutdown and recovery, and a front‑panel “P/S ACTIVE” green LED that confirms the DC outputs are within regulation. A rear‑mounted sense/jumper block allows configuration for single‑supply operation (jumper in the right‑hand position) or parallel redundant operation with a second 1771‑P6S​ or compatible unit via the 1771‑CT sense cable for increased reliability in critical continuous‑process applications. No software configuration is required—the supply is detected automatically by the PLC‑5 processor, which monitors rack power status and reports under‑voltage or power‑loss conditions through system status files (S:FS flags) and CPU LEDs.As a cornerstone component of legacy yet still widely deployed PLC‑5 automation systems, the Allen‑Bradley 1771‑P6S​ delivers the robust, continuous‑duty power foundation required by heavy industrial process lines, batch plants, and large‑scale machine control cabinets that continue to rely on the 1771 architecture for mission‑critical operations.

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Description

 

Technical Specifications

Product Model 1771-P6S
Manufacturer Rockwell Automation / Allen‑Bradley
Product Type 1771 Series Rack Power Supply Module (AC Input)
Input Voltage 194–264 VAC, 47–63 Hz (single‑phase)
Input Current (Max) Approx. 1.0 A @ 230 VAC full load
Backplane Output Voltage 5.06 VDC ±2%
Backplane Output Current 8.0 A maximum (40.5 W)
Total Output Power Approx. 56 W (including auxiliary bias)
Isolation (Input to Output/Chassis) 2500 VDC for 1 s; meets UL 508 / IEC 61131‑2 reinforced insulation
Protection Over‑current limiting, over‑voltage crowbar with auto‑recovery; fused AC input (user‑replaceable)
Indicator Green “P/S ACTIVE” LED – illuminated when 5 VDC output is within regulation
Rack Compatibility 1771‑A1B, 1771‑A2B, 1771‑A3B, 1771‑A4B chassis (installs in dedicated power slot)
Parallel Operation Supported with second supply + 1771‑CT sense cable; rear jumper selects local (right) or parallel (left) sense
Operating Temperature 0 °C to 60 °C (32 °F to 140 °F)
Storage Temperature –40 °C to 85 °C
Humidity 5% to 95% non‑condensing
Mounting 1771 chassis dedicated power slot (leftmost); keyed to prevent insertion in I/O slots
Dimensions (approx.) 356 × 127 × 152 mm (14 × 5 × 6 in) typical 1771 module footprint
Wire Size (AC Input) 14–18 AWG stranded/solid, stripped 6–7 mm
Certifications UL listed, cUL, CE, C‑Tick, FM Class I Div 2 (certain approvals), RoHS compliant (later revisions)

 

Main Features and Advantages

High‑capacity 8 A backplane output for dense I/O loading: The 1771‑P6S​ provides up to 8.0 A of regulated 5 VDC to the 1771 backplane—sufficient to power a PLC‑5 processor (e.g., 1771‑L5 series) together with a full complement of digital (1771‑Ix / 1771‑Ox) and analog (1771‑IFxx / 1771‑OFxx) modules in an 8‑ or 16‑slot rack. This eliminates the need to calculate multiple smaller supplies and simplifies rack design for complex process or machine control panels still running the PLC‑5 platform.220 VAC global input with robust isolation: Designed for 194–264 VAC mains, the 1771‑P6S​ is the standard 230 V variant for international deployments (contrast with the 1771‑P4S, which is the 120 VAC version). Input to output isolation rated at 2500 VDC protects the low‑voltage control system from line transients and ground faults. The module’s over‑current fold‑back and over‑voltage crowbar circuits safeguard both the supply and connected 1771 modules in the event of abnormal load conditions, automatically resuming normal operation once the fault clears.Parallel redundant configuration support: Through a rear‑panel sense‑jumper and the optional 1771‑CT sense cable, two 1771‑P6S​ units can be paralleled in a single rack to share load current and provide redundancy—if one supply fails, the second continues to power the rack without interruption. This feature is particularly valued in continuous‑process industries (oil & gas, pulp & paper, power generation) where unplanned downtime for power supply replacement is undesirable. The 1771‑P6S​ also supports single‑supply operation with the sense jumper in the default (rightmost) position.Clear status indication and PLC‑5 integration: The front‑panel green “P/S ACTIVE” LED gives immediate visual confirmation of healthy DC output. The PLC‑5 processor continuously monitors backplane voltage through the power‑good circuit and can trigger a fault routine or latched alarm bit (S:FS – First Scan / System Fault Status File) if supply voltage drops below the valid threshold, enabling the control program to execute an orderly shutdown or transition to a safe state before complete power loss.Legacy system longevity and interchangeability: As an original‑equipment 1771 power module, the 1771‑P6S​ is fully backward‑compatible with all generations of PLC‑5 processors and 1771 I/O ever produced for the platform. It is the direct, drop‑in replacement for aging or failed 1771‑P6S units in existing racks, requiring no rewiring of the AC input or rack backplane—only removal of the old module and insertion of the new 1771‑P6S, followed by a power‑up verification.

Application Field

The 1771‑P6S​ is specified wherever a 1771‑series rack—hosting a PLC‑5 processor or acting as a remote 1771 I/O bank—requires local AC‑derived DC backplane power. In pulp & paper mills, steel rolling mills, and petrochemical process plants that standardized on the PLC‑5 architecture during the 1990s and early 2000s, the 1771‑P6S​ remains the workhorse power source for main control racks containing the 1771‑L5x processor, analog input modules reading 4–20 mA signals from field transmitters, and high‑density discrete I/O interfacing with motor starters, solenoids, and limit switches.Remote I/O racks connected via a 1771‑ASB (Allen‑Bradley Serial/Remote I/O Adapter) or 1785‑KA (ControlNet/DH+ gateway) also require a 1771‑P6S​ in each physically separate chassis to energize the adapter and all resident I/O modules. Automotive powertrain and body‑shop lines, water/wastewater treatment plants, and power‑generation auxiliary systems with legacy PLC‑5 installations similarly depend on the 1771‑P6S​ for reliable, continuous rack power. In all these contexts, the module’s parallel‑redundancy option is frequently employed in critical process areas to eliminate the power supply as a single point of failure. For sites planning phased migration away from PLC‑5 while keeping existing 1771 I/O in place (via 1756‑A17/1771‑AENTR or similar bridges), the 1771‑P6S​ continues to serve as the interim rack power source until final decommissioning.

Related Products

  • 1771‑P4S​ — 120 VAC input version of the same 8 A 1771 rack power supply; electrically identical except for the 98–132 VAC input range—used in North American panels with 120 VAC service.
  • 1771‑P6P​ — Similar to the 1771‑P6S but with a +5 VDC @ 8 A plus an auxiliary +24 VDC @ 1 A output for certain legacy 1771 modules requiring 24 V field power from the rack supply.
  • 1771‑P7 / 1771‑PS7​ — Higher‑capacity or standalone 1771 power supply variants; 1771‑PS7 provides 16 A backplane current and may be used in very large or special‑configuration racks.
  • 1771‑CT​ — Sense cable used to connect two 1771‑P6S (or P4S) supplies in parallel for redundant/load‑share operation; required when configuring the 1771‑P6S​ for dual‑supply mode.
  • 1771‑A2B​ — 8‑slot 1771 I/O chassis (typical size) into which the 1771‑P6S​ is installed at the leftmost power slot.
  • 1771‑L55M22 / 1771‑L53​ — Example PLC‑5 processors that reside in the same rack powered by the 1771‑P6S; the processor’s backplane current draw must be included in the total load budget.
  • 1771‑IF16 / 1771‑OW16​ — Typical 1771 analog input and AC output modules whose cumulative 5 V backplane current is supplied by the 1771‑P6S.
  • 1785‑L80E​ — PLC‑5/80 Ethernet‑enabled processor; also powered from a rack supplied by the 1771‑P6S.
Contact Us WhatsApp / Wechat：+86 18150087953
Phone：+86 18150087953
Email：sales@cxplcmro.com

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