Description
DS3800HMPJ1AD Product Overview
The DS3800HMPJ1AD is an auxiliary microprocessor board that plugs into GE Mark IV turbine and EX2000 exciter control racks. Occupying a 6BA Euro-card slot, it acts as a distributed processing node: it hosts a local 24 Vdc microprocessor, executes fast auxiliary control algorithms (e.g., lube-oil sequencing, cooling-fan logic), and buffers high-speed data between the main CPU (NDIA bus) and field I/O while isolating the 5 V processor from the 480 V class power electronics. The “AD” suffix indicates this is an earlier revision than the A1D variant, with subtle differences in default jumper settings and firmware compatibility. Because all copper traces are fully encapsulated in high-temperature epoxy, the unit is treated as a line-replaceable module—any internal fault requires a complete card swap rather than component-level rework. The module is fully hot-swappable when the rack is powered down, and its 0.90 lb weight allows adjacent-slot population without additional card guides.
The DS3800HMPJ1AD is an auxiliary microprocessor board that plugs into GE Mark IV turbine and EX2000 exciter control racks. Occupying a 6BA Euro-card slot, it acts as a distributed processing node: it hosts a local 24 Vdc microprocessor, executes fast auxiliary control algorithms (e.g., lube-oil sequencing, cooling-fan logic), and buffers high-speed data between the main CPU (NDIA bus) and field I/O while isolating the 5 V processor from the 480 V class power electronics. The “AD” suffix indicates this is an earlier revision than the A1D variant, with subtle differences in default jumper settings and firmware compatibility. Because all copper traces are fully encapsulated in high-temperature epoxy, the unit is treated as a line-replaceable module—any internal fault requires a complete card swap rather than component-level rework. The module is fully hot-swappable when the rack is powered down, and its 0.90 lb weight allows adjacent-slot population without additional card guides.
GE DS3800NGRC1F1F
DS3800HMPJ1AD Technical Specifications
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Model Number: DS3800HMPJ1AD
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Manufacturer: General Electric (GE Fanuc)
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Product Type: Microprocessor / Auxiliary CPU Board
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Series: DS3800, Mark IV Speedtronic
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Power Supply: 24 Vdc nominal (18–36 Vdc range)
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Form Factor: 6BA Euro-card (≈ 233 × 160 mm)
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Back-Plane Connector: Dual 40-pin header (J1/J2)
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Processor: Local 24 V micro-CPU (optimized for fast industrial control loops)
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Isolation: 1500 Vdc field-to-logic; opto-coupled data lines
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Operating Temperature: 0 – 60 °C
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Weight: 0.90 lb (≈ 0.41 kg)
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Construction: Epoxy-sealed copper traces—non-repairable
Core Features & Customer Value
24 V Local Processing: The on-board microprocessor runs at 24 Vdc, off-loading fast auxiliary loops (lube pumps, cooling fans) from the main 5 V CPU. This guarantees deterministic response times even when the central processor is busy with sequencing or communications, reducing the risk of auxiliary-trip delays during start-up.
Epoxy-Sealed Construction: All internal copper is encapsulated in high-temperature epoxy. In coastal or industrial sites with conductive dust and high humidity the seal prevents trace-to-trace shorting that would otherwise cause random “AUX MPU FAIL” alarms after ten-plus years of service. The trade-off is non-repairability—any internal fault requires a whole-card exchange—but this is offset by the reduced troubleshooting time and the fact that plants stock one spare instead of maintaining a repair bench.
AD Revision Compatibility: The “AD” suffix indicates this is an earlier hardware revision than the A1D. Key differences include default jumper settings for input thresholds and subtle timing variations in the local CPU firmware. When replacing an AD with an A1D (or vice versa), always verify jumper positions against the job drawing to ensure compatible behavior.
GE DS3800NGRC1F1F
Typical Applications
In combined-cycle power plants the board is installed in the Mark IV turbine control core where it hosts the auxiliary sequencing logic for the 24 Vdc lube-oil pump, cooling-fan contactors, and hydraulic trip solenoid. The on-board opto-isolators keep 480 V switching transients from walking into the 5 V CPU data bus.
On utility-scale EX2000 static exciters the same card is used to manage the brushless-exciter cooling-fan starter and the field-discharge contactor. Because the inputs are group-isolated, a shorted fan motor will not drag down the entire digital I/O rack.
Frequently the same part number is used on mechanical-drive gas compressors to sequence the 24 Vdc inlet-guide-vane hydraulic pump. Its ability to mix 24 V logic with isolation on one card makes it a universal “auxiliary CPU” for any Mark IV loop that needs deterministic, battery-free operation.
