ABB PP846A (3BSE042238R2) — High-Integrity Redundant Power Supply Module for AC800M DCS Systems

Let’s cut to the chase: if you’re maintaining or expanding an ABB AC800M-based distributed control system—especially in power generation, refining, or chemical plants—you’ve likely run into voltage dips, brownouts, or unplanned controller resets that trace back to marginal power conditioning. The PP846A isn’t just another PSU—it’s ABB’s dual-redundant, hot-swappable 24 VDC power supply module engineered specifically to keep your AC800M controllers and I/O modules running through grid instability, battery switchover delays, or even brief UPS failures. From my experience supporting brownfield retrofits across Europe and the Gulf, this module quietly solves more uptime headaches than most engineers realize—until it’s missing.

Key Features

• True 1+1 redundancy with automatic load sharing — Both units operate in parallel under normal conditions; if one fails, the other picks up 100% load instantly—no interruption to controller operation.
• Hot-swappable design — You can replace a failed unit without powering down the rack. One thing I appreciate is how the status LEDs (OK, FAULT, SYNC) give immediate visual feedback—even in dimly lit cabinets.
• Wide input voltage tolerance (85–264 VAC, 47–63 Hz) — Handles severe sags and surges common in industrial switchgear environments. In many cases, it eliminates the need for upstream isolation transformers.
• Integrated diagnostics & communication via AC800M backplane — Reports health status, output current, temperature, and fault history directly to Control Builder M—no external SCADA polling required.
• UL/cUL Class 1 Div 2 and ATEX Zone 2 certified — Certified for use in hazardous locations without additional barriers, which simplifies compliance documentation on offshore platforms or solvent-handling lines.

Technical Specifications

Application Fields

This module shows up where reliability isn’t optional: turbine control systems in combined-cycle power plants, emergency shutdown (ESD) logic solvers in LNG terminals, and batch sequencing controllers in pharmaceutical cleanrooms. A customer in Rotterdam recently told us their PP846A pair survived three consecutive lightning-induced voltage collapses during a storm—while older non-redundant PSUs downstream tripped offline. It’s also frequently specified in brownfield upgrades where legacy AC800M racks are being extended but can’t accommodate newer modular power solutions due to backplane compatibility constraints.

Advantages & Value

If you’re evaluating this against generic DIN-rail PSUs or even competing OEM modules, here’s what matters: First, full firmware-level integration with AC800M means no custom HMI scripting to monitor supply health—you get alarms and trending out of the box. Second, the 365-day warranty (standard, no upcharge) covers both parts and labor—including diagnostics via remote support. Third, because it’s built to ABB’s S800 ecosystem specs, you avoid compatibility surprises during firmware updates—something we’ve seen derail commissioning timelines with third-party alternatives. And yes, it costs more upfront than a basic 24 VDC supply—but when downtime runs $18k/hour in a refinery, that premium typically pays back in under 11 months.

Installation & Maintenance

Mount it in an IP54-rated cabinet with ≥200 mm clearance above/below for convection cooling—ABB’s thermal derating curve gets aggressive past 45°C ambient. Use only shielded 2.5 mm² (14 AWG) copper for input wiring, and terminate all grounds at a single point near the PSU—not daisy-chained. Avoid routing power cables parallel to signal cables; cross them at 90° if necessary. For maintenance: check fan operation (yes, it has a quiet axial fan) every 6 months; clean dust filters with compressed air; and verify output ripple (<50 mVpp) annually using an oscilloscope—if it creeps above 80 mVpp, consider replacement even if no fault is reported. Firmware updates are rare (typically once every 2–3 years), but always apply them before major controller upgrades.

Quality & Certifications

CE marked (2014/30/EU EMC, 2014/35/EU LVD), UL 61010-1 & cULus listed, RoHS 2011/65/EU compliant, and certified for ATEX II 2G Ex ec IIC T4 Gc and IECEx Ex ec IIC T4 Gc. ABB backs it with a standard 365-day warranty from date of shipment—covers manufacturing defects, field failures, and includes free return shipping for evaluation. Extended warranties (up to 3 years) are available upon request, though most users find the base coverage sufficient given the module’s field MTBF of >200,000 hours.