Description
DS3800NLCA1F1F Product Overview
The DS3800NLCA1F1F is a logic control auxiliary board that plugs into GE Mark IV turbine and EX2000 exciter control racks. Occupying a 6BA Euro-card slot, it acts as a digital logic “front end”: it buffers 5 V CMOS signals from the CPU, converts them to 24 Vdc field levels, executes auxiliary control sequences (lube pump logic, cooling fan control, valve solenoid timing), and isolates the processor from 480 V switching transients. 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 low-profile epoxy package allows adjacent-slot population without additional cooling.
The DS3800NLCA1F1F is a logic control auxiliary board that plugs into GE Mark IV turbine and EX2000 exciter control racks. Occupying a 6BA Euro-card slot, it acts as a digital logic “front end”: it buffers 5 V CMOS signals from the CPU, converts them to 24 Vdc field levels, executes auxiliary control sequences (lube pump logic, cooling fan control, valve solenoid timing), and isolates the processor from 480 V switching transients. 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 low-profile epoxy package allows adjacent-slot population without additional cooling.
DS3800NLCA1F1F
DS3800NLCA1F1F Technical Specifications
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Model Number: DS3800NLCA1F1F
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Manufacturer: General Electric (GE Fanuc)
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Product Type: Logic Control Auxiliary / Digital Buffer Board
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Series: DS3800, Mark IV Speedtronic
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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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Logic Levels: 5 V CMOS/TTL (CPU side); 24 Vdc (field side)
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Isolation: 1500 Vdc field-to-logic; opto-coupled I/O lines
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Update Rate: 2 ms (synchronized to CPU scan)
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Power Demand: +5 V @ 0.8 A, +24 V @ 0.5 A from rack 2PL bus
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Operating Temperature: 0 – 60 °C
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Weight: ≈ 0.22 kg
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Construction: Epoxy-sealed copper traces—non-repairable
Core Features & Customer Value
Level-Shifting Logic Buffer: The on-board translators convert 5 V CMOS to 24 Vdc with <1 µs propagation delay, ensuring solenoid valves and contactors respond immediately to CPU commands. For the control engineer this eliminates external relay boards and reduces wiring complexity, cutting panel space and installation time.
Auxiliary Sequence Execution: The local logic array executes fast subroutines (pump alternation, fan staging, valve interlocks) without burdening the main CPU. This guarantees deterministic response even when the central processor is busy with turbine sequencing or communications, preventing auxiliary-trip delays during critical start-up phases.
Epoxy-Sealed Construction: All internal copper is encapsulated in high-temperature epoxy. In environments with high humidity, dust, or conductive contamination the seal prevents trace-to-trace shorting that would otherwise cause random “LOGIC 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 reduced troubleshooting time and the fact that plants stock one spare instead of maintaining a repair bench.
DS3800NLCA1F1F
Typical Applications
In combined-cycle power plants the board is installed in the Mark IV turbine control core where it executes the lube-oil pump alternation logic, cooling-fan staging sequence, and hydraulic trip solenoid control. The on-board opto-isolators keep 480 V contactor 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 logic and the field-discharge contactor interlock. Because the outputs 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 inlet-guide-vane hydraulic pump and the anti-surge valve solenoids. Its ability to mix 5 V logic processing with 24 V field drive on one card makes it a universal “auxiliary logic engine” for any Mark IV loop that needs fast, deterministic, battery-free operation.
