ABB PM851 Modules | PM851 3BSE018169R1 Power Supply Module

Technical Dossier

Product Details And Specifications

ABB PM851 Series: Comprehensive Module Range and Technical Overview

The ABB PM851 is a processor and power supply module belonging to the AC800M controller family, ABB's flagship DCS/PLC platform deployed across global heavy industry. The AC800M system — and the PM851 series within it — holds significant installed base in petrochemical refineries, nuclear power auxiliary systems, pulp and paper mills, offshore oil and gas platforms, and large-scale chemical processing facilities. The PM851 3BSE018169R1 specifically functions as a combined CPU and power supply unit, providing the computational core and regulated DC power distribution for the AC800M controller rack. Its dual-function architecture reduces rack footprint and simplifies cabling in space-constrained control cabinets. The AC800M platform, including PM851 variants, is certified for use in SIL-rated safety loops when paired with appropriate safety I/O modules, making it a standard reference in IEC 61511 compliant installations.

The Evolution of PM851 Architecture

The AC800M controller family was introduced by ABB in the late 1990s as a successor to the Advant OCS and Master series platforms. The PM851 processor module represents the mid-range tier of the AC800M CPU lineup, positioned between the entry-level PM856 and the high-performance PM860/PM861 variants. Early revisions of the PM851 operated on the MMS (Manufacturing Message Specification) communication stack over Ethernet, with firmware managed via the Control Builder M engineering tool. Subsequent hardware revisions introduced improved SDRAM capacity, expanded flash storage for application programs, and enhanced EMC shielding to meet IEC 61000-4 industrial immunity standards.

The PM851 communicates with I/O modules via the S100 I/O bus and supports the CI854/CI857/CI858 communication interface modules for PROFIBUS DP, FOUNDATION Fieldbus H1, and HART integration respectively. As the AC800M platform matured, ABB introduced the PM891 and PM895 as functional successors, offering faster cycle times and expanded memory. However, the PM851 remains in active service across thousands of installed systems globally, and its 3BSE018169R1 hardware revision continues to be the most widely referenced spare part number in maintenance BOMs for plants commissioned between 2000 and 2015. Compatibility between PM851 hardware revisions and specific Control Builder M software versions must be verified against ABB's firmware compatibility matrix prior to replacement.

PM851 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified components within the ABB AC800M PM851 ecosystem and associated module families. Each entry reflects a distinct hardware article number used in ABB's spare parts and engineering documentation.

PM851 3BSE018169R1: AC800M processor/power supply module, 24VDC input, standard memory configuration, primary CPU for mid-range AC800M racks.
PM851A 3BSE018168R1: PM851 variant with extended temperature rating for harsh environment enclosures.
PM856 3BSE018100R1: Entry-level AC800M CPU module, reduced I/O capacity, single Ethernet port, used in smaller standalone controller configurations.
PM856A 3BSE018161R1: PM856 with extended memory, supports larger application programs and additional function block libraries.
PM860 3BSE018100R1: High-performance AC800M CPU, dual Ethernet ports, redundancy-capable, used in critical process control loops.
PM860A 3BSE018161R1: PM860 with expanded SDRAM and flash, supports high-density I/O configurations exceeding 2000 I/O points.
PM861 3BSE018168R1: Top-tier AC800M processor, hardware-redundant CPU architecture, sub-50ms failover, used in SIL 2/3 safety applications.
PM861A 3BSE018169R1: PM861 with enhanced cybersecurity firmware, supports role-based access control and encrypted Ethernet communication.
CI854 3BSE025255R1: PROFIBUS DP communication interface module for AC800M, supports up to 125 slave devices per segment.
CI857 3BSE018168R1: FOUNDATION Fieldbus H1 interface module, supports 16 FF devices per segment, integrated LAS functionality.
CI858 3BSE018100R1: HART multiplexer interface module, provides HART pass-through for up to 16 HART-enabled field instruments.
CI860 3BSE032444R1: IEC 61850 communication interface for substation automation integration with AC800M controllers.
TB820V2 3BSE013208R1: ModuleBus modem module, extends S100 I/O bus over fiber optic cable up to 1000m for remote I/O cabinets.
SD821 3BSC610037R1: 24VDC power supply unit for AC800M rack, 5A output, primary power source for controller and I/O modules.
SD822 3BSC610038R1: 24VDC redundant power supply module, hot-swap capable, used in high-availability controller configurations.
SD823 3BSC610065R1: 48VDC input power supply for AC800M, used in telecom-standard power environments.
TP830 3BSE018168R1: Touch panel operator interface, 10.4-inch TFT display, direct connection to AC800M via Ethernet for local HMI applications.
MB510 3BSE002540R1: ModuleBus cluster modem, used for multi-rack I/O expansion within a single AC800M controller station.

Sourcing Hard-to-Find & Obsolete PM851 Parts

The PM851 3BSE018169R1 and several associated AC800M modules have entered the mature-to-declining phase of their product lifecycle. ABB has formally announced end-of-manufacturing for select PM851 hardware revisions, with long-term support transitioning to the PM891/PM895 platform. For plants with remaining operational life of 5–15 years, full migration is not always economically justified, creating sustained demand for original PM851 spare parts and tested refurbished units.

DriveKNMS maintains a dedicated inventory of AC800M PM851 series modules sourced from decommissioned plant equipment, authorized surplus channels, and direct OEM overstock. All units are catalogued by hardware revision and firmware version to ensure compatibility with the customer's existing Control Builder M project version. DriveKNMS provides lifecycle extension support including cross-reference verification, hardware revision compatibility analysis, and documentation of known firmware constraints for PM851 units operating under specific Control Builder M software releases. Emergency same-day dispatch is available for critical plant shutdown scenarios.

Quality Control for the PM851 Range

The PM851 3BSE018169R1 integrates a combined CPU and power regulation circuit on a single PCB assembly, requiring specialized test procedures that address both computational and power delivery functions simultaneously. DriveKNMS applies the following verification protocol to all PM851 units prior to dispatch:

Power rail verification is performed using calibrated DC load banks to confirm 5VDC, 12VDC, and 24VDC output stability under rated load conditions. CPU functional testing is executed by loading a reference AC800M application via Control Builder M in a live rack environment, verifying program execution, I/O scan cycle time, and Ethernet communication integrity. S100 ModuleBus communication is tested by connecting the PM851 to a populated I/O rack and confirming error-free data exchange across all addressed module slots. Firmware revision is documented and reported with each unit. Units exhibiting capacitor degradation, PCB corrosion, or non-standard firmware are quarantined and not offered for sale. Each tested unit ships with a DriveKNMS inspection certificate and 12-month warranty against functional defects.