ABB MC91 HESG440588R4 HESG112714/B Microcomputer / Central Processor Module
ABB MC91 (HESG440588R4 / HESG112714/B) is a specialized Microcomputer / Processor Module belonging to the ABB Procontrol P13 system.
It is part of the high-reliability HESG series, which was specifically engineered for the rigorous demands of power generation and large-scale industrial automation.
1. Introduction
The MC91 is a central intelligence unit for the Procontrol P13 rack. It is designed to perform complex control functions,
signal monitoring, and data processing. The module operates as a programmable logic unit that communicates via the P13 parallel bus to coordinate I/O modules and higher-level controllers.
The HESG440588R4 indicates the module’s assembly revision, while HESG112714/B refers to the internal motherboard hardware version.
2. Technical Parameter Table
| Parameter | Specification |
| Model Number | MC91 |
| Primary Part Number | HESG440588R4 |
| Hardware Revision | HESG112714/B |
| Module Type | Microcomputer / Central Processor Module |
| Processor Type | High-reliability 16-bit / 32-bit Architecture |
| Supply Voltage | +5V DC (Logic) / +24V DC (Field Interface) |
| Power Consumption | ~6.5 W (Typical) |
| Memory Type | EPROM (Firmware) / RAM (Working Memory) |
| Operating Temp | 0°C to +60°C |
| Bus Interface | P13 Parallel System Bus |
| Diagnostic Display | Front-panel LEDs (Run, Error, Block) |
3. Related Models
MC92: A later iteration with enhanced memory capacity for larger logic blocks.
70PR05: A more modern processor module used as a successor in P13 systems.
AB91-1: An arithmetic unit often used as a co-processor for the MC91.
500PSM03: The standard high-capacity power supply module used to power MC91 racks.
4. Product Advantages and Features
Deterministic Logic Execution: Ensures that safety-critical control loops (like turbine trips or boiler interlocks) execute within strictly defined time windows.
HESG Military-Grade Standards: Built with components selected for extreme durability, often resulting in an operational lifespan of over 25 years.
Self-Monitoring: Includes a “Watchdog” timer that automatically resets the module or triggers a safety shutdown if the internal software execution hangs.
Galvanic Isolation: The interface to the system bus is isolated to prevent electrical faults from spreading across the rack.
Legacy Compatibility: Seamlessly integrates with older P13 subracks, making it a vital component for extending the life of existing power plant control systems.
5. Application Cases
Boiler Protection Systems: Managing the logic for Burner Management Systems (BMS) where reliability is non-negotiable.
Hydroelectric Control: Regulating gate positions and generator synchronization.
Steam Turbine Monitoring: Processing high-speed analog data for overspeed protection and vibration analysis.
Substation Automation: Controlling high-voltage bay units and interlocking sequences.
6. Installation and Maintenance
Installation:
Jumper Settings: Before installation, ensure the “Station Address” jumpers on the HESG112714/B board match the system engineering documentation.
Insertion: Align the module with the Eurocard guide rails and push firmly until the 96-pin connector is fully seated. Tighten the front panel screws to ensure a good ground connection.
Maintenance:
Battery Maintenance: If the module is configured with a RAM backup battery, it should be replaced every 2–3 years to prevent losing the application program during power cycles.
Connector Integrity: During shutdowns, inspect the gold-plated backplane pins for oxidation. Clean with an approved residue-free contact cleaner if necessary.
Visual Diagnostics: A steady Green LED indicates healthy operation. A Red LED usually signifies a hardware failure or a bus communication conflict.
Dust Management: Since the MC91 can generate moderate heat, ensure the subrack’s vertical airflow is not obstructed by dust or other equipment.