Description
1. Product Overview
ABB PAD238A101, part number 3BHE029063R0101, is a dedicated core control board for ABB UNITROL series generator excitation systems. It acts as the critical unit for signal acquisition and logical computation in power‑plant excitation control systems. Designed for excitation regulators of medium‑to‑large synchronous generators, steam‑turbine generators and hydro‑turbine generators, the board mainly performs excitation‑related signal sampling, closed‑loop regulation calculation, pulse signal distribution, system condition monitoring and fault‑protection output. It serves as the core industrial‑control board to guarantee stable generator terminal voltage, precise reactive‑power regulation and reliable grid‑parallel operation of generator sets.
The PAD238A101 adopts industrial‑grade high‑reliability hardware architecture, with full‑board moisture‑proof & anti‑corrosion coating and anti‑electromagnetic‑interference design, adapting to harsh operating conditions in power plants featuring high temperature, high humidity, strong electromagnetic interference and long‑term non‑stop operation. As an original key spare part for UNITROL excitation systems, this model is widely used for matching excitation systems of new and legacy generating units, technical retrofits of old equipment, as well as maintenance replacement of faulty boards. It delivers outstanding performance including high calculation accuracy, fast regulation response, superior operational stability, excellent anti‑interference capability and long service life, and functions as an original core component for power‑industry excitation automation systems.
2. Functional Features
High‑precision excitation signal acquisition and sampling Integrated with high‑accuracy AD sampling units, the board collects key operating parameters in real‑time, such as generator terminal voltage, stator current, rotor excitation current and system bus voltage. It achieves high sampling precision and extremely low temperature drift, effectively eliminating voltage fluctuation, reactive‑power oscillation and unstable grid‑paralleling caused by sampling deviation, and provides accurate raw data for excitation closed‑loop regulation.
Core excitation closed‑loop regulation and computation Equipped with ABB proprietary excitation PID algorithm, the board automatically implements intelligent closed‑loop regulation for voltage, reactive power and power factor. It dynamically modifies excitation output according to unit load variation and grid fluctuation, stabilizes generator terminal voltage and reactive‑power output precisely, mitigates impacts of grid disturbances on unit operation, and ensures compliant steady‑state and transient performance of generating units.
- SCR pulse triggering and distribution control
Providing multi‑channel high‑precision pulse output, the board synchronously drives SCR rectifier modules within excitation power units. It accurately controls rectifier firing angles to realize smooth adjustment of excitation current without pulse offset, trigger distortion or output jitter. It ensures stable output of excitation power units and supports full‑condition operation including no‑load, on‑load, grid‑paralleling and overload.
Comprehensive fault monitoring and protection logic Embedded with complete fault‑monitoring logic for excitation systems, the board continuously detects various faults such as excitation over‑voltage, under‑voltage, over‑current, loss‑of‑excitation, excitation abnormality, sampling failure and pulse anomaly. It identifies fault types accurately and triggers corresponding protective actions including fault alarming, amplitude‑limiting regulation and emergency de‑excitation, so as to avoid unit tripping, equipment damage and grid fluctuation induced by excitation faults.
Multi‑mode operation with wide condition compatibility It supports multiple operation modes including automatic excitation, manual excitation, constant‑voltage, constant‑reactive‑power and constant‑power‑factor modes. It covers full‑scenario conditions such as unit startup/shutdown, no‑load operation, grid‑connected power generation, peak‑load regulation and fault redundancy. Smooth mode switching without impact makes it compatible with excitation systems of thermal‑power, hydro‑power and combined‑heat‑and‑power generating units.
Industrial‑grade anti‑interference and high‑stability design Multi‑layer PCB layout and optimized EMC design are adopted. Circuits for signal filtering, surge suppression and electrical isolation are integrated to resist electromagnetic interference from strong magnetic fields, high‑voltage apparatus and frequency‑conversion devices in power plants. It prevents signal drift, logical misjudgment, pulse abnormality and false board alarms under complex electromagnetic environments of power stations.
- Standardized field‑bus communication and data interaction Supporting internal bus communication for excitation systems, it conducts real‑time data exchange with main control units, power units and HMI panels. It uploads excitation operating parameters, fault codes and status information of generating units, and receives regulating commands from upper computers to realize remote monitoring, parameter modification and fault tracing, which fits centralized automatic operation‑maintenance mode of power plants.
3. Technical Parameters
3.1 Basic Specifications
Product Model: PAD238A101 Part Number: 3BHE029063R0101 Manufacturer: ABB (Original, Switzerland) Product Series: UNITROL Excitation Control System Product Type: Excitation Sampling & Regulation Main‑Control Board Core Function: Core unit for signal acquisition, closed‑loop regulation, pulse triggering and fault protection of generator excitation systems Key Characteristics: High‑precision sampling, intelligent PID regulation, multi‑channel pulse output, full‑condition fault protection, strong anti‑interference, long‑life industrial‑grade design
3.2 Electrical Parameters
Power Supply: Standard industrial DC power supply, compatible with dedicated power modules for excitation systems Sampling Accuracy: Industrial high‑precision AD sampling, minor error, stable temperature drift Regulation Response: Millisecond‑level dynamic response, suitable for scenarios with rapid grid fluctuation Output Mode: Multi‑channel synchronous pulse trigger output, compatible with SCR rectifier power units Communication Mode: Dedicated internal bus for excitation systems, high‑speed and stable data interaction
3.3 Control Performance Parameters
Regulation Modes: Constant voltage, constant reactive power, constant power factor, manual excitation, automatic excitation Protection Functions: Loss‑of‑excitation protection, over‑excitation protection, under‑excitation protection, over‑voltage & over‑current protection, sampling‑fault protection, pulse‑fault protection Control Algorithm: ABB optimized dedicated excitation PID closed‑loop algorithm, high steady‑state accuracy and fast transient response Application Scope: Full‑condition power‑generation operation of medium‑to‑large synchronous generators
3.4 Hardware Structure Parameters
Board Technology: Multi‑layer high‑precision industrial PCB, full‑board moisture‑proof, anti‑corrosion and dust‑proof conformal coating Installation: Slot‑type embedded mounting in standard cabinets Interfaces: Sampling signal ports, pulse output ports, power ports, bus communication ports, status indicator LEDs Structural Feature: Compact standardized form factor, fits cabinet layout of UNITROL series excitation systems, convenient for plug‑in and removal
3.5 Environmental Parameters
Operating Temperature: 0℃ ~ +60℃ Storage Temperature: ‑20℃ ~ +70℃ Relative Humidity: 5%‑95%, non‑condensing Protection Class: Board‑level conformal coating protection, for indoor cabinet installation in power plants Operation Mode: 7×24‑hour non‑stop continuous operation Application Sites: Excitation systems for thermal‑power plants, hydro‑power plants, combined‑heat‑and‑power plants and captive power plants
4. Hardware Configuration & Structural Advantages
High‑precision sampling architecture for superior regulation stability Equipped with imported high‑accuracy sampling chips and isolated operational circuits, it delivers outstanding precision for voltage and current sampling. It captures subtle operating‑condition variations of generating units and adjusts excitation output in real‑time via closed‑loop algorithms. Common defects including voltage drift, reactive‑power oscillation and unstable grid‑paralleling are effectively solved, improving power‑generation quality of units and grid stability significantly.
Multi‑loop highly‑integrated design Six core functions including signal sampling, logical computation, closed‑loop regulation, pulse triggering, fault protection and data communication are integrated onto one single board. No additional auxiliary boards are required. It simplifies hardware architecture of excitation systems, reduces potential fault points and enhances integration level as well as overall reliability.
Industrial conformal coating for harsh power‑plant environments Full‑board moisture‑proof, anti‑corrosion and dust‑proof conformal coating is applied. All components are industrial‑grade wide‑temperature tolerant devices, enduring high temperature, humidity, dust and strong electromagnetic interference in power‑plant workshops. The board resists oxidation and moisture ingress without parameter degradation, supporting long maintenance‑free operation.
Millisecond‑level dynamic response with excellent transient performance With proprietary optimized excitation algorithm, it responds rapidly. When grid disturbance, load step change, unit paralleling or dis‑paralleling occurs, excitation parameters are adjusted quickly to restrain sharp voltage rise‑and‑fall. It improves transient stability of generating units and grid anti‑disturbance capacity to meet grid‑connection standards for power systems.
Standardized compatible design for high interchangeability Fully compliant with original ABB UNITROL hardware standards, it shares identical pin‑out definition, program logic and parameter configuration with original systems. Faulty boards on legacy units can be directly hot‑swapped in‑situ without program modification, rewiring or complex commissioning. Normal unit operation can be restored rapidly, lowering downtime loss and maintenance costs.
- Visual status monitoring for convenient O&M On‑board LED indicators display running, fault and communication status. Cooperated with upper‑level HMI, excitation operating parameters, fault codes and historical records can be checked in real‑time for accurate fault tracing and rapid troubleshooting. It reduces maintenance workload for power plants and adapts to unattended and intelligent operation‑maintenance modes.
5. Application Scenarios
Excitation systems for medium‑to‑large thermal‑power generating units: deployed in UNITROL excitation control systems for synchronous generators of thermal‑power plants to realize voltage stabilization, reactive‑power adjustment, grid‑paralleling control and fault protection, securing stable power output of main thermal‑power units.
Excitation control systems for hydro‑power generating units: applied for hydro‑power plant generators. It handles frequent hydraulic‑load fluctuation, performs dynamic and precise excitation adjustment, and satisfies requirements for frequency‑peak‑regulation and variable‑load operation.
Combined‑heat‑and‑power and captive‑power‑plant units: used for factory captive power plants and CHP units to guarantee stable unit operation and qualified power quality, meeting requirements of on‑site power supply and grid‑connection compliance.
Technical‑retrofit & upgrade projects for excitation systems: for hardware upgrading and performance optimization of legacy ABB excitation systems. Obsolete low‑performance boards are replaced to improve regulation precision, stability and automation degree.
- Maintenance‑replacement spare parts for power‑plant excitation systems: as original core spare parts, it is widely adopted for in‑situ replacement of aged or damaged excitation boards in various power stations to restore equipment capacity quickly. It belongs to critical stocked spare parts for power plants.
