DS3800XPEX1B1A | GE OEM Mark VIe Terminal Board

Description

Product Introduction

The DS3800XPEX1B1A is the 48V DC input variant of GE’s extended-capacity power module—20A output at 5V, with the same high-current design as the 24V XPEX, but with an input stage rated for 48V nominal. The “B” in the suffix tells you it’s configured for higher voltage—typically used in plants with 48V battery strings or long cable runs where voltage drop is a concern. The board has the same 20A capacity as the 24V version, so you get full backplane power from a higher-voltage source.

This board shows up in larger turbine installations—think Frame 9 gas turbines, large steam turbines, or combined-cycle plants where the control system is stepped up to reduce cable size or where existing plant power is 48V. The “1A” suffix indicates enhanced EMI filtering (knocks down high-frequency noise from VFDs and motor starters) plus an acrylic conformal coating for moderate protection against humidity. The input stage uses FETs and transformers rated for the higher voltage, and the undervoltage lockout shifts from 18V to about 38V—if you feed 24V into this board, it simply won’t start. Typical buyers are plant engineers with 48V plant power looking for high-capacity spares, or teams upgrading from 24V to 48V systems.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: Can I hot-swap this power module?

No. The Mark VIe backplane requires power removal before installation or removal. Pulling this live risks arcing on the backplane connector and voltage transients that can damage downstream boards. The 20A capacity means more stored energy on the output caps, so the spark when you pull it is bigger. Power down the entire I/O pack. We’ve seen field techs ignore this and take out adjacent analog boards.

Q: Can I use this board with a 24V input if I’m in a pinch?

No. The undervoltage lockout is set to 38V. Below that, the board won’t start—the LEDs stay dark. It’s not a fuse or soft-start issue; it’s a deliberate design to protect the FETs from low-voltage operation. If you only have 24V available, you need the 24V version (DS3800XPEX1A1A). Don’t try to bypass the lockout; it’s there for a reason.

Q: How is the “1B1A” different from the “1A1A” variant?

Three differences:

• Input voltage: 1B1A is 48V nominal; 1A1A is 24V. The input FETs and transformer are rated for the higher voltage, and the undervoltage lockout is 38V vs. 18V.
• Input current: At full 20A output, the 48V version draws about 6A (versus 12A for the 24V version). That means smaller wire gauge and less voltage drop on long runs.
• Suffix: The “B” in the second position indicates the voltage configuration. The rest (enhanced filtering, coating) is the same as the 1A1A.

The output capacity is identical—20A at 5V. So if you have 48V available, this board gives you the same backplane power as the 24V version, just from a different input.

Q: My plant has two 48V battery strings. How do I wire redundancy?

The XPEX1B1A has a single input. For redundancy, you need external OR-ing diodes (Schottky) between your two 48V sources and the board’s input. The board itself doesn’t have internal diodes. Choose diodes rated for at least 10A continuous (about 1.5x your worst-case input current). The board does monitor the single input voltage and reports it to the controller—so you’ll know if the feed drops, but it won’t switch automatically without the external diodes.

Q: How do you test this board before shipping?

We run a 6-step load test with 48V input and a 20A load—the full capacity:

• Visual inspection: Check for swollen capacitors, burnt FETs, cracked screw terminals. Inspect the EMI chokes for discoloration. Look at the heat sink—if it’s warped or discolored, the board has thermal stress.
• ESD check: Insulation resistance between input terminals and chassis ground must exceed 10MΩ.
• Initial power-up: Apply 48V DC and verify soft-start limits inrush to <12A. Check the undervoltage lockout by lowering input to 37V (board shuts down) then raising back to 48V (board restarts).
• No-load output: Measure the 5V DC rail unloaded. Must be within ±2% (4.9-5.1V).
• Load test: Apply a 20A resistive load to the 5V rail. Monitor voltage regulation (4.9-5.1V), ripple (<50mV p-p), and temperature rise. FETs must stay below 75°C. We verify the thermal sensor reading matches our reference.
• 24-hour soak: Run at 20A load at 50°C ambient. Log output voltage, temperature, and current every hour. Failure threshold: voltage <4.85V, temperature >80°C, or trip.

We reject about 18% of these boards at the soak step—the 48V input stresses the FETs differently than the 24V version, and some fail under long-term load. That’s why we don’t skip the 24-hour test.

Q: What’s the most common failure on this board?

Three things specific to the 48V high-current design:

• FET burnout: The higher input voltage increases switching losses in the FETs. Over time, they degrade and can fail. We replace FETs on about 35% of the 48V XPEX boards we refurbish—the highest rate of any power module.
• Transformer stress: The 48V-to-5V transformer runs hotter than the 24V version. If the board is in a cabinet above 50°C, the transformer can overheat and short. We check transformer temperature during the soak test.
• Capacitor aging: The input capacitors are rated at 63V (near the 60V maximum). If your battery string floats at 57V, they’re close to their limit. Aged caps can bulge or leak.

Q: What does the “1B1A” suffix mean?

On GE’s Mark VIe power module naming:

• 1: Base design revision
• B: Input voltage configuration (48V DC nominal)
• 1: Specific component batch (FETs, thermal sensor)
• A: Conformal coating (acrylic)

So this board is a specific configuration with 48V input, enhanced filtering, and acrylic coating. If you need the same filtering but no coating, you’d look for “1B10” (uncommon). If you need a heavier epoxy coating, you’d look for “1B1C” or similar.

Q: What size wire should I use for the 48V input?

At 20A output, the input current is about 6A at 48V. That means you can use 14 AWG or even 16 AWG for short runs (under 10 meters). For longer runs, factor in the voltage drop—the board needs at least 38V at the terminals. We recommend 12 AWG for runs over 20 meters to keep the voltage drop under 1V. Also use ferrules on stranded wire to prevent loose connections—we’ve seen terminal block heating from poorly terminated wires.

Q: Can I run a 12-slot rack with this board?

Yes, and you can exceed the 12-slot limit if your rack supports it. At 20A:

• Up to 16 analog input boards (1.2A each = 19.2A)
• Up to 13 analog output boards (1.5A each = 19.5A)
• Up to 15 mixed boards, depending on their draw

We recommend leaving 20% margin—so target 16A continuous load maximum. If your expansion plan exceeds that, you’d need a second power module or a different rack architecture. The 48V input doesn’t change the output capacity.

Q: Are there counterfeit versions of this board?

Yes, and the FETs are a giveaway. Here’s what we look for:

• FET brands: Genuine boards use known vendors (Infineon, ON Semi) with specific part numbers rated for 48V input and 20A output. Counterfeits use off-brand FETs that fail the 20A load test.
• Transformer markings: The genuine 48V-to-5V transformer has specific part numbers and a distinctive appearance. Counterfeits use generic transformers that overheat.
• Capacitor ratings: Genuine input caps are rated at 63V. Counterfeits sometimes use 50V caps—they’ll work at 48V but fail if the battery string floats to 57V.
• Coating: Genuine coating is uniform and matte. Fakes use cheaper lacquer.
• Label: Same as other GE boards—matte finish with greenish barcode vs. glossy off-white.

We trace our stock to decommissioned assets. If you’re buying elsewhere, demand photos of the component side, the serial sticker, and close-ups of the FET and transformer markings.

Q: Can I use this board in a Mark VIe TMR system?

Yes. In a TMR rack, you’ll have three XPEX1B1A boards—one per controller. They share the same backplane but are diode-isolated internally. If one power module fails, the other two continue to power the I/O. We recommend using the same revision across all three controllers—don’t mix a 1B1A with a base XPEX in a TMR system, as the monitoring logic might trip on mismatched temperature readings.

Q: What’s your warranty on this board?

We offer a 1-year warranty against functional defects. If the board fails to meet published specs within that period and hasn’t been damaged or miswired, we’ll replace or refund. For high-capacity power supplies, we also cap the warranty at 30 days if you install it without testing—we can’t guarantee field damage from external surges or wiring faults.

Q: What’s the lead time?

We typically carry 1-2 units of the XPEX1B1A in stock—the 48V high-capacity version is less common, so availability varies. If you order before 2 PM EST, we ship within 1-2 business days after testing. The 24-hour load test is non-negotiable—we won’t skip it. If you need expedited shipping, we can rush the initial load test and ship next-day, but you sign a waiver acknowledging the long-term soak was skipped. For critical systems, we strongly recommend waiting for the full test cycle—the 48V FETs only show thermal drift after hours at full load, and a 2-hour test won’t catch that.

ABB CI867K01
SIEMENS 6AV2124-0QC02-0AX0
SIEMENS 6AV6643-0CD01-1AX1
ABB ECS086329-003