G3: The High-Voltage End of the EACF Family

IS200EACFG3B is the G3 version of GE's Exciter AC Feedback board, built for the highest of the three input voltage classes in this board family — a nominal 1300 Vrms three-phase input, compared to roughly 480 Vrms for G1 and 1000 Vrms for G2. It's a less common spare simply because fewer exciter systems run at that voltage class, which is exactly why it's worth confirming carefully against your existing board's label rather than assuming any EACF will do: these three versions are built for different input ranges and are not interchangeable.

What the Board Does

Like the rest of the EACF family, this board measures the exciter's three-phase AC supply voltage and current and reports it back to the EX2100 excitation regulator, which uses that feedback to hold generator field excitation stable. Voltage inputs are stepped down through onboard potential transformers to a nominal 1.6 V rms signal level; current is sensed through flux/air-core coils and filtered against high-frequency noise. Processed measurements fan out to three DB9 connectors serving the M1, M2, and C controllers in the EX2100's redundant architecture, and the board's own connection to the EBKP backplane can run up to 90 meters.

Where It Sits

EACF is mounted in the EX2100 exciter auxiliary cabinet — a separate system from the Mark VI turbine control VME rack, even though both use GE's IS200 part-numbering convention. If this board is being sourced off a generic "Mark VI" parts list, double-check that the requirement is actually the excitation side of the plant, not turbine control I/O.

Diagnose the Feedback Path First

• A voltage regulation complaint or feedback alarm is often a blown PT fuse or damaged field wiring ahead of the board, not the EACF itself.
• Check each DB9 cable to the M1, M2, and C controllers individually before assuming the board has failed on all three feedback paths at once.
• Inspect the cable run to the EBKP backplane, particularly if it's near the 90-meter limit.
• Confirm G3 (1300 Vrms) is genuinely the correct class for this exciter — not a leftover assumption from a previous, possibly incorrect, replacement.

The Part Number

IS200EACFG3B IS200EACFG3BAA: EACF is the functional code, G3 specifically denotes the 1300 Vrms input class, B marks the board-type revision, and AA tracks the specific hardware revision. Our part number decoder covers how every segment of a Mark VI/EX2100 part number is structured.

Related Boards

BICL and its matching Bridge Personality Interface board (BPIA/BPIB/SCNV) are common companions in the same excitation cabinet. See our Mark VI IS200 boards collection for more.

What to Send With Your RFQ

• Full part number and suffix (IS200EACFG3BAA), with a label photo if possible
• Confirmed exciter voltage class (G1/G2/G3)
• Generator/turbine model and site
• Quantity and urgency

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