ABB NF93A-2 Main PCB Card, Part Numbers: HESG440280R2, HESG323662R1, HESG216665K This main control board belongs to ABB legacy INFI-90 distributed control system (DCS), acting as the core unit for system signal processing, bus communication and logic operation. It integrates digital I/O signal conditioning circuits, 16-bit high-precision analog-to-digital converters, INFI-Net high-speed bus interfaces and isolated multi-protocol communication circuits. Built in a European-style VME rack plug-in format, it is developed for spare part replacement, system expansion and matching with ageing DCS installations across power, chemical, metallurgical and other process industries.
Manufactured in compliance with industrial standards including IEC 61131, CE and UL, the board undergoes rigorous testing covering temperature cycling, electromagnetic interference resistance and extended ageing validation, making it an essential spare component for all existing INFI-90 systems.
Equipped with an independent processing chip, the card acquires digital and analog field signals to execute closed-loop regulation, logic interlock functions and fault diagnostics. It enables bidirectional data exchange with controllers, operator workstations and other I/O modules via the backplane bus. A single card is capable of handling full measurement and control tasks for small-to-medium process sections, and is widely applied in maintenance replacement and system retrofits for legacy industrial automation facilities.
Technical Specifications
(1) Hardware Structural Parameters
Main Model: NF93A-2Three-tier part codes: Complete assembly HESG440280R2; Main control core board HESG323662R1; PCB base board HESG216665KMounting Type: Plug-in card for European VME rack, compatible with standard cabinet slotsPower Supply: 24V DC ±10%, total power consumption ≤5W, input current 0.5APhysical Dimensions: 203mm×152mm×51mm, net weight 0.8kgIngress Protection: IP20 (for cabinet internal installation)Certifications: CE EMC compliance, UL industrial component certification, IEC 61000 immunity standard
(2) Signal & Channel Performance
Digital Channels: 16-channel 24V DC digital input with optoelectronic isolation, millisecond-level signal response, compatible with field proximity switches, valve position feedback and interlock contactsAnalog Conversion: 16-bit high-precision ADC/DAC, supporting standard industrial analog signals of 4-20mA and 0-10V, measurement error ≤±0.05% FSIsolation Design: 1500V AC galvanic isolation across all I/O channels, communication buses and power circuits, protecting the main control chip from damage caused by field surge and leakage current
(3) Communication & Computing Performance
Equipped with high-speed processor; interlock fault response time ＜10ms, overvoltage/overcurrent protection activation time ＜20ms, meeting fast protection requirements of power equipmentDual on-board INFI-Net backplane bus ports for high-speed data exchange with DCS controllers and operator workstationsExternal Ethernet and serial communication terminals supporting Modbus TCP and Modbus RTU protocols for connection to third-party SCADA monitoring systemsLocal Storage: On-board cache for fault logs and process parameters; data retention ≥30 days after power loss to support post-failure trace analysis
(4) Environmental Reliability Specifications
Operating Temperature: -40℃ ~ +85℃Storage Temperature: -40℃ ~ +85℃Relative Humidity: 5%~95% RH, non-condensingVibration Resistance: Compliant with IEC 60068; no solder detachment or functional failure under continuous vibration ranging from 5Hz to 150HzEMC Immunity: Resistant to radiated radio frequency, electrostatic discharge and electrical fast transient bursts, suitable for high-interference environments such as steel rolling mills and workshops with high-power motors
Core Advantages
Fully matched unified part codes for trouble-free replacement
Three part numbers HESG440280R2, HESG323662R1 and HESG216665K are factory-binded to one single PCB assembly. When purchasing spare parts, there is no need to separately verify the codes of base board, core control board and complete unit. The whole card can be directly replaced, eliminating failures such as bus recognition loss and channel breakdown caused by replacing individual components.
Industrial-grade stability under wide operating conditions
It operates continuously at operating and storage temperatures ranging from -40℃ to +85℃, as well as 5%–95% relative humidity without condensation. All channels feature 1500V AC optoelectronic isolation. No signal drift or false triggering occurs in harsh workshops with heavy electromagnetic interference, dust, extreme high or low temperatures, making it ideal for power plants, refineries and other demanding industrial sites.
Integrated multi-functional design to save cabinet space
A single card integrates four core functions: signal acquisition, logic control, bus communication and fault waveform recording. It replaces the conventional combination of separate acquisition and communication cards, cutting cabinet slot occupation by over 30% and reducing system wiring and potential hardware failure points.
Hot-swap capability minimizes downtime
Adopting standard VME rack hot-plug design, faulty cards can be removed and replaced online without shutting down the entire DCS system. Single card replacement takes less than 5 minutes, drastically shortening maintenance downtime for production lines and generator units.
Multi-protocol compatibility for communication between new and legacy systems
Natively supporting the internal INFI-Net bus, it is also compatible with Modbus TCP/RTU and standard Ethernet protocols. It can work seamlessly with complete original INFI-90 systems and connect to third-party monitoring hosts, PLCs and recorders, perfectly suiting digital retrofits of outdated control systems.
Comprehensive on-board self-diagnosis boosts maintenance efficiency
Equipped with hardware fault indicator lights and real-time data log storage, the card records faults including channel short circuits, bus disconnections, power supply anomalies and chip malfunctions. Remote access to fault waveforms is supported, enabling rapid fault location without manual multimeter testing of each channel.
Application Industries
Thermal, Hydropower & Wind Power Generation
Measurement and control of auxiliary equipment for generator sets, signal acquisition of excitation systems, logic control for auxiliary power protection, and interlock signals for wind turbine pitch control. It serves as a replacement for faulty boards of legacy INFI-90 systems and realizes generator protection against overcurrent, reverse power and frequency deviation.
Petrochemical & Oil/Gas Storage and Transportation
Closed-loop regulation of temperature, pressure and flow in refining facilities, interlock control of pipeline valves, and collection of flammable gas alarm signals. It acts as a spare core measurement & control unit for DCS installed inside explosion-proof cabinets.
Metallurgy & Steel Industry
Automated control of roller tables and heating furnaces in steel rolling production lines, on-site signal processing in workshops with high temperature and heavy dust, and stable logic operation under severe electromagnetic interference.
Cement, Paper & Other Process Manufacturing
Continuous monitoring of production process parameters, variable frequency linkage of fans and water pumps, equipment safety interlock, as well as capacity expansion and component replacement for outdated distributed control systems.
Water Treatment & Municipal Energy
Pressure and flow control of pipe networks in sewage pumping stations and water plants, and matching control boards for DCS systems of municipal heating boilers.
FAQ
Q1: The three part codes HESG440280R2, HESG323662R1 and HESG216665K are different. Can they be used interchangeably for replacement?A: No. These three codes respectively correspond to the complete assembly, core board and base board of a single NF93A-2 card, which are bound one-to-one at the factory. If only one code matches while the others are inconsistent, issues including unrecognized bus communication, loss of channel signals and power-on error alarms will occur. All three codes must fully match those of the original board when placing orders.
Q3: What are the common causes of steady red indicator light after powering on the board?A: Four frequent faults are listed as follows:
- Reversed positive and negative poles of the 24V power supply, or input voltage lower than 22V;
- Poor contact caused by oxidized gold fingers. Pull out the card, wipe the gold fingers clean and reinsert it;
- Short circuit on field I/O channels resulting in breakdown of channel isolation chips;
- Hardware address conflict within the DCS system. Reassign the board address via the engineering workstation.
Q4: Can NF93A-2 be applied to ABB AC800M and AC500 PLC systems?A: They are incompatible. NF93A-2 is exclusively designed for the INFI-90 DCS. Its backplane hardware bus and communication protocols cannot be identified by AC800M and AC5000 PLC platforms. Corresponding AC-series I/O modules shall be adopted for PLC systems instead.
Q6: The readout of on-site 4-20mA analog signal keeps drifting. Does this mean the board is damaged?A: External factors should be checked first: poor shielding grounding of signal cables or unstable power supply for field transmitters. If external faults are ruled out, inspect the isolation circuit of the corresponding channel on NF93A-2. Aging channel chips will lead to analog signal drift, which can be fixed by replacing the entire card directly.
Q7: The board supports hot swap. Is system shutdown still required during replacement?A: It depends on working conditions:
- For ordinary auxiliary process sections: Hot swap can be performed online after interlock bypass is activated without system shutdown;
- For generator sets and main process units with critical interlocks: The whole system must be powered off before replacement, to avoid safety shutdown interlock triggered by instantaneous bus fluctuation during plugging and unplugging.
Q8: Has NF93A-2 been discontinued? Is long-term spare parts supply guaranteed in the future?A: The original INFI-90 system has been discontinued by the manufacturer. Nevertheless, NF93A-2 is a widely used core spare part for existing projects. Automation suppliers maintain abundant brand-new original stocks, ensuring sufficient supply within the next 5 years. For long-term renovation plans, upgrading to ABB’s latest 800xA DCS as a replacement solution is available
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