Product Overview
The ABB 3BHE032025R0101 (PCD235A101) is the exciter control CPU module — often called the “excitation master” — at the heart of ABB UNITROL 6000 static excitation systems, and also deployable in UNITROL 1000 frames and AC 800PEC-based excitation racks. It occupies Slot A of the PBA (Power & Control / Processor Board Assembly) 3U rack, plugging into the S100 high-speed backplane that interconnects the ADCVI analog/digital sampling board, the GFD233A communications board, and the local I/O cluster. The ABB PCD235A101 succeeds the earlier PCD230 and is itself succeeded by the UNS2880B-P (migration requires a full SI retrofit kit including backplane, CCI and firmware). Across tens of thousands of hydro, thermal and gas-gen sets worldwide, the PCD235A101 has been the workhorse AVR controller since the mid-2000s UNITROL 6000 rollout.
Functionally, the ABB 3BHE032025R0101 hosts a 32-bit RISC embedded processor (Motorola/PowerPC lineage depending on hardware revision) running ABB’s AVR firmware: automatic voltage regulation (AVR), manual/auto transfer, PID control loop, PSS2A power-system stabilizer, and the standard exciter limiter suite — OEL (over-excitation), UEL (under-excitation), MEL (minimum excitation) — all executing with <100 ms response to grid disturbances. Generator terminal voltage and stator current are sampled through the adjacent ADCVI board via PT/CT secondaries brought to the rack; the ABB PCD235A101 closes the loop digitally and issues firing commands to the thyristor power cubicle (typically GSD231) over fiber, while publishing setpoints, actuals and limiter statuses to the plant DCS through the GFD233A or onboard ANYIO ports.
Physically the ABB 3BHE032025R0101 is a 3U × 73.5 mm-wide plug-in card (≈373 × 73.5 × 142 mm, ~1.53 kg), IP20 for cabinet mount, operating from dual redundant 24 V DC (20–28 V) with hot-swap support, and internally regulated to 5 V DC for the S100 backplane and logic. Three analog inputs (±10 V / ±20 mA, 16-bit Σ-Δ ADC), three analog outputs (±10 V, 12-bit), twelve 24/48 V dry-contact DI, sixteen Form-C relay DO (250 V AC / 5 A), and three PT100/PTC temperature inputs give the card direct interfacing to cubicle fans, field-breaker coils, de-excitation contactors, local alarm lamps and winding/ bearing temperature probes — meaning a single ABB PCD235A101 covers both the AVR algorithm and the ancillary cubicle I/O that older split-architecture designs spread across two or three boards.
From a lifecycle standpoint, the ABB 3BHE032025R0101 is now a legacy A-class critical spare: ABB has migrated the UNITROL 6000 new-production line to UNS2880B-P, so PCD235A101 stocks are finite. Plants running PCD235-based UNITROL 6000 are advised to last-time-buy and maintain at least one buffer unit per cubicle (or a centralized pool across multiple sets), because this card failing = generator forced off-line.
Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | ABB 3BHE032025R0101 () |
| Manufacturer | ABB (Switzerland / Sweden) |
| Product Type | Exciter Control Module / AVR CPU Board (UNITROL 6000 PBA Slot A) |
| Processor | 32-bit RISC embedded (Motorola/PowerPC, rev-dependent) |
| Memory | DRAM (runtime) + Flash/EEPROM (parameters, firmware, event recording); typical slot-in EEPROM card |
| External Supply | Dual redundant 24 V DC (20–28 V), hot-swap supported |
| Internal Backplane | 5 V DC ±5% (S100 bus power, typical 8–15 W module consumption) |
| Analog Inputs (AI) | 3 × ±10 V or ±20 mA, differential/single-ended, 16-bit Σ-Δ ADC |
| Analog Outputs (AO) | 3 × ±10 V, 12-bit resolution |
| Digital Inputs (DI) | 12 × , compatible 24 V / 48 V dry contact |
| Relay Outputs (DO) | 16 × Form C, 250 V AC / 5 A or 30 V DC / 5 A |
| Temperature Inputs | 3 × PT100 / PTC (exciter winding, bearing, cubicle) |
| Control Accuracy | ±0.5% FS (terminal voltage regulation) |
| Response Time | < 100 ms (AVR loop, grid-disturbance rejection) |
| Control Functions | AVR (auto/manual), PID, PSS2A, OEL, UEL, MEL |
| Backplane Bus | S100 high-speed bus (to ADCVI, GFD233A, local I/O) |
| External Comms | ANYIO-1: RS422 / CEX2-BUS; ANYIO-2: Modbus TCP (optional); RS232/RS485 |
| Fiber Interface | 3 × high-speed fiber transceivers (to thyristor power cubicle, e.g. GSD231) |
| Configuration Tool | ABB PCM600, CMT (Control & Measurement Tool) |
| Indicators (LED) | RUN / ERR / WD / COM (rev-dependent silkscreen) |
| Operating Temp. | –25 °C to +70 °C |
| Storage Temp. | –40 °C to +85 °C, 5%–95% RH non-condensing |
| Mounting | 3U plug-in, vertical into PBA rack Slot A |
| Enclosure / IP | IP20 (cabinet install) |
| Dimensions (H×W×D) | 373 × 73.5 × 142 mm (3U card format) |
| Weight | ≈ 1.53 kg |
| Standards | IEC 61000-4-x EMC, CE, IEEE 421.5 (system-level) |
| Successor | ABB UNS2880B-P (full retrofit kit required) |
| Predecessor | ABB PCD230 |
