DS3800NFCD | Replacement for DS3800NFCD

Description

Product Introduction

The DS3800NFCD is the fiber optic backbone of the Mark IV control system—the board that connects the CPU to remote I/O cabinets, operator workstations, and other turbine control nodes. The “F” in the suffix indicates fiber optic communications, and the “CD” identifies this as a dual-channel version with enhanced diagnostics. The board mounts in the Mark IV rack and provides electrically isolated, noise-immune communication over distances up to 2 kilometers. It was typically used in combined cycle plants where the gas turbine and steam turbine control cabinets are separated by long cable runs, or in installations where electrical noise from high-voltage equipment could corrupt copper links.

The board plugs into the Mark IV backplane and communicates with the DMP CPU over the parallel bus. The fiber optic transceiver operates at 2Mbps—fast enough to handle the Mark IV’s I/O scanning and data logging requirements. Compare this to the DS3800NECA Ethernet board (10Base2 coaxial). The NFCD offers electrical isolation and longer cable runs, while the NECA integrates with plant-wide TCP/IP networks. The NFCD is the board you use when you need a dedicated, hardwired, noise-immune link between Mark IV cabinets.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

What’s the difference between the NFCD and the NFCC?
The NFCD and NFCC are functionally identical—both are dual-channel fiber optic boards with the same 2Mbps data rate, 850nm wavelength, and ST connectors. The suffix indicates different manufacturing batches. The NFCD was the later revision, but GE didn’t make any functional changes. If you’re replacing an NFCC with an NFCD, it’s a direct drop-in. The NFCD is slightly more common in our inventory.

Can I use single-mode fiber with this board?
No, the NFCD uses 850nm LED transceivers designed for multimode fiber. Single-mode fiber won’t work—the transceiver doesn’t have enough power to couple into the smaller core. You’ll need 62.5/125µm multimode fiber with ST connectors. If you have single-mode fiber installed, you’ll need a media converter or a different board.

What’s the maximum distance I can run with this board?
The NFCD is rated for 2km with 62.5/125µm fiber and a 3dB/km loss budget. In practice, we’ve seen it run up to 3km on good fiber with low connector loss. If you’re exceeding 2km, you should test the link before commissioning. The diagnostic LEDs on the board will indicate link quality—if the link is marginal, the Error LED will flash. We’ve seen customers push it to 3.5km with premium fiber and clean connectors.

Is the fiber optic link redundant?
The NFCD has two channels (A and B), but they’re not redundant in the sense of failover. They’re two independent links to two different remote nodes—typically one for the operator workstation and one for a remote I/O cabinet. For redundancy, you’d need two NFCD boards (in separate CPU racks) or a different architecture. The Mark IV doesn’t support automatic failover on the fiber links—it’s a point-to-point protocol.

What’s the protocol used on the fiber link?
GE uses a proprietary protocol that’s not compatible with standard industry protocols like Profibus or Modbus. The NFCD communicates directly with the DMP CPU over the backplane—there’s no protocol stack for external devices. If you need to connect to non-GE equipment, you’ll need a gateway or a different communication board (like the NECA). The NFCD is for GE-to-GE communication only.

Can I hot-swap this board?
No. Mark IV backplanes are not hot-swappable. Pulling the NFCD with power applied can cause voltage spikes on the backplane. Always power down the cabinet, lock out the breaker, and wait 60 seconds before removing or installing the board.

What’s the most common failure mode on the NFCD?
We’ve serviced about 25 NFCD boards over the past six years. The most common failure is the LED transceiver—it degrades over time, reducing the optical power output. The symptom is intermittent link drops or the Link LED staying off. The fix is replacing the transceiver (a standard ST LED module). The second most common failure is the edge connector—corrosion from humidity. We clean it with a fiberglass brush and isopropyl alcohol. The board is repairable.

What’s your warranty and lead time?
We stock the NFCD in our Dallas and Houston warehouses. Lead time is 1-2 business days. We offer a 1-year warranty on functional defects. 30-day return window for unused boards—full refund minus shipping. We test every NFCD with a 24-hour burn-in and a fiber optic loopback test before shipping. The test report is included.

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