Description
DS3800NSFA1D1E: Product Overview
This board occupies a 6BA Euro-card slot in GE Mark IV turbine and EX2000 exciter control racks, serving as a field switch status interface for monitoring discrete inputs from mechanical and electrical devices. It accepts dry-contact closures and 24 Vdc wetting voltage signals from limit switches, pressure switches, flow switches, and breaker auxiliary contacts, provides 1500 Vdc group isolation to protect the 5 V CPU from ground loops and transients, and debounces the inputs to prevent false transitions from contact bounce. The “NSFA” designation indicates switch/field auxiliary functionality, while the D1E revision includes enhanced debounce algorithms and LED status indicators for each channel.
This board occupies a 6BA Euro-card slot in GE Mark IV turbine and EX2000 exciter control racks, serving as a field switch status interface for monitoring discrete inputs from mechanical and electrical devices. It accepts dry-contact closures and 24 Vdc wetting voltage signals from limit switches, pressure switches, flow switches, and breaker auxiliary contacts, provides 1500 Vdc group isolation to protect the 5 V CPU from ground loops and transients, and debounces the inputs to prevent false transitions from contact bounce. The “NSFA” designation indicates switch/field auxiliary functionality, while the D1E revision includes enhanced debounce algorithms and LED status indicators for each channel.
The epoxy-sealed construction makes this a line-replaceable module—internal faults require complete card swap rather than field repair. The module hot-swaps when the rack is powered down, and its low profile allows adjacent-slot population without additional cooling. As part of the DS3800 family, it benefits from the Mark IV platform’s deterministic 2 ms control interval and extensive installed base in power generation applications.
GE DS3800NGRC1F1F
DS3800NSFA1D1E: Technical Specifications
-
Model Number: DS3800NSFA1D1E
-
Manufacturer: General Electric (GE Fanuc)
-
Product Type: Switch/Field Auxiliary / Field Status Input Board
-
Series: DS3800, Mark IV Speedtronic
-
Form Factor: 6BA Euro-card (≈ 233 × 160 mm)
-
Back-Plane Connector: Dual 40-pin header (J1/J2)
-
Input Channels: 16 (dry contact or 24 Vdc, jumper-selectable in banks of 4)
-
Input Impedance: 10 kΩ pull-up to 24 Vdc (wet mode); 100 kΩ to 5 V (dry mode)
-
Isolation: 1500 Vdc channel-to-ground; group-isolated in 4-channel banks
-
Update Rate: 2 ms (synchronized to CPU scan)
-
Debounce Time: 5–50 ms selectable (D1E enhancement)
-
Indicators: Per-channel LED status (D1E addition)
-
Power Demand: +5 V @ 0.6 A, +24 V @ 0.4 A from rack 2PL bus
-
Operating Temperature: 0 – 60 °C
-
Weight: ≈ 0.24 kg
-
Construction: Epoxy-sealed copper traces—non-repairable
Core Features & Customer Value
Flexible Input Configuration: The bank-selectable wet/dry input capability allows mixing 24 Vdc powered switches and simple dry contacts on the same card. For system integrators, this eliminates separate cards for different switch types, reducing spare inventory and simplifying wiring documentation.
Enhanced Debounce and Visibility: The D1E revision adds software-selectable debounce times (5–50 ms) and per-channel LEDs. For maintenance technicians, the LEDs provide immediate visual confirmation of switch state without needing a multimeter or laptop connection, cutting troubleshooting time by 50% or more in field verification scenarios.
Epoxy-Sealed Construction: All internal copper is encapsulated in high-temperature epoxy. In coastal or industrial environments with conductive dust and high humidity, this prevents trace-to-trace shorting that would cause random “SWITCH FAIL” alarms or false transitions after ten-plus years. The trade-off is non-repairability—internal faults require whole-card exchange—but this is offset by reduced troubleshooting time and single-spare stocking rather than maintaining a repair bench.
GE DS3800NGRC1F1F
Typical Applications
In combined-cycle power plants, this board installs in the Mark IV turbine control core where it monitors the full complement of turbine protective switches: bearing vibration trip, overspeed bolt, low lube pressure, high exhaust temperature, and generator differential lockout. The 16-channel capacity handles an entire turbine protection suite on one card.
On utility-scale EX2000 static exciters, the same card tracks the brushless-exciter diode-fail contact, field ground detector, and cooling-air flow switch. The selectable debounce prevents nuisance alarms from brief flow fluctuations during start-up transients.
Mechanical-drive gas compressors frequently use this part number for the complete set of compressor protective switches: high discharge temperature, low suction pressure, high vibration, and anti-surge valve position limit. The per-channel LEDs allow rapid field verification during commissioning and maintenance without disturbing control wiring.
