ABB AB91-1 HESG437479R1 HESG437899 Arithmetic / Adaptation Unit
ABB AB91-1 (HESG437479R1 / HESG437899) is a specialized Processing or Communication Interface Module from the Procontrol P13 family.
In the P13 naming convention, “AB” modules typically function as Arithmetic/Logic or Adaptation Units,
used to perform complex mathematical operations or to link different segments of the P13 bus system.
1. Introduction
The AB91-1 is a vintage yet highly reliable industrial component designed for power plant and substation automation.
It acts as a specialized processing node that handles data adaptation between the local bus and higher-level control units.
The hardware revision HESG437479R1 represents the full assembly, while HESG437899 often refers to the specific printed circuit board (PCB) layout.
2. Technical Parameter Table
| Parameter | Specification |
| Model Number | AB91-1 |
| Primary Part Number | HESG437479R1 |
| PCB Part Number | HESG437899 |
| System Compatibility | Procontrol P13 |
| Module Type | Arithmetic / Adaptation Unit |
| Voltage Supply | +5V DC (Logic) / +24V DC (Field/Bus) |
| Power Consumption | ~5W to 8W |
| Data Width | 8-bit / 16-bit processing architecture |
| Operating Temp | 0°C to +60°C |
| Connection Type | 96-pin DIN Connector (Standard Eurocard) |
3. Related Models
AB91-2: A later iteration with expanded memory or faster clock speeds.
AB96: A higher-capacity arithmetic unit for complex turbine calculations.
70PR05: The general-purpose processor module that often commands the AB91-1.
IW93-2: Analog interface module frequently paired with AB units for signal processing.
4. Product Advantages and Features
High-Speed Logic Execution: Designed specifically for real-time industrial tasks, offering lower latency than general-purpose I/O modules.
Galvanic Isolation: Protects the internal system bus from external electrical faults, ensuring that a field-side spike doesn’t crash the entire controller.
Proven Longevity: Part of ABB’s HESG series, which is famous for maintaining operational integrity for over 30 years in harsh environments.
Self-Check Diagnostics: The module continuously performs parity checks and internal hardware audits, flagging errors via LEDs before they cause a process failure.
Seamless Bus Integration: Fully compatible with the P13 parallel backplane, requiring minimal software overhead for data exchange.
5. Application Cases
Boiler Control Logic: Performing the mathematical scaling and limit-checking required for steam pressure and temperature control.
Turbine Governance: Calculating the complex derivative and integral (PID) values needed for stable turbine speed regulation.
System Expansion: Acting as a bridge to link legacy P13 racks to newer monitoring hardware.
Custom Logic Blocks: Used when standard binary or analog modules lack the computational “intelligence” to perform specific site-required sequences.
6. Installation and Maintenance
Installation:
Jumper Verification: Before sliding the module into the rack, ensure any physical jumpers for the Station Address are set correctly to prevent bus collisions.
Insertion: Always use the card ejectors/levers to seat the module firmly. Do not force the module if it resists; check for bent pins on the 96-pin DIN connector.
Maintenance:
Voltage Monitoring: During routine maintenance, verify the +5V logic supply at the backplane test points; a drop below 4.75V can cause the AB91-1 to behave erratically.
LED Indicators: Green usually indicates “Run/OK,” while Red/Yellow indicates a fault or block. A “dark” module usually points to a fuse or power supply failure.
Cleaning: Use a vacuum and anti-static brush for the rack; do not use liquid cleaners on the module unless they are certified 100% residue-free for high-frequency electronics.