G1, G2, G3: This Board Comes in Three Voltage Classes — Order the Right One

IS200EACFG1A is the G1 version of GE's Exciter AC Feedback (EACF) board for the EX2100 excitation control system, rated for a single three-phase input around 480 Vrms (+20%) at 50/60 Hz. GE also builds this same board as G2 (rated around 1000 Vrms) and G3 (rated around 1300 Vrms) for higher-voltage exciter systems. These aren't interchangeable revisions of the same part — they're built for different input voltage ranges, so the G-designator is the first thing to confirm against your existing board's label before ordering a replacement, not an afterthought.

What an Exciter AC Feedback Board Actually Does

EACF measures the exciter's AC supply voltage and current and feeds that information back to the EX2100 Excitation Control System, which uses it for voltage regulation and stable generator operation. Three-phase voltage inputs are stepped down by onboard potential transformers to a nominal 1.6 V rms signal level, while current inputs from flux/air-core coils are filtered to suppress high-frequency noise before being processed. Both voltage and current measurement outputs are fanned out to three DB9 connectors, cabled to the M1, M2, and C controllers in the EX2100's redundant architecture. It's located in the exciter auxiliary cabinet, and the cable run from EACF to the EBKP backplane board can be as long as 90 meters.

This Is EX2100, Not Mark VI Turbine Control

Like several other boards using GE's IS200 numbering convention, EACF sometimes shows up mislabeled as a generic "Mark VI" circuit board. It isn't part of the turbine control VME rack — it belongs to the EX2100 excitation system that regulates generator field current, a companion system that shares a control philosophy and part-numbering scheme with Mark VI but runs in its own cabinet.

Before You Order a Replacement, Check These

• Voltage regulation instability or a lost feedback alarm doesn't automatically mean the EACF failed. Check the potential transformer fuses and field wiring feeding the board first — a blown PT fuse produces the same symptom as a bad feedback channel.
• Check the DB9 cables to the M1, M2, and C controllers. A damaged or disconnected cable on one leg looks like a feedback fault on that controller, not necessarily a board failure.
• Confirm the connection to the EBKP backplane board, especially on long cable runs approaching the 90-meter limit — connector or cable degradation over that distance is a real possibility.
• Verify you're ordering the correct voltage class (G1/G2/G3) for your exciter before assuming a fault is even a hardware failure and not a mismatched board installed previously.

Reading the Part Number

IS200EACFG1A IS200EACFG1ABC: EACF is the functional board code, G1 identifies the 480 Vrms input class specifically (versus G2 for 1000 Vrms and G3 for 1300 Vrms), and the characters that follow (here, A, BC) track assembly variant and revision. Always match the complete string, not just the EACF prefix. Our GE Speedtronic part number decoder explains the full naming convention shared across Mark VI and EX2100 boards.

Related EX2100 Boards

EACF is typically ordered alongside BICL (Bridge Interface) and its matching Bridge Personality Interface board (BPIA/BPIB/SCNV) elsewhere in the same excitation cabinet. See our Speedtronic turbine control boards collection for the full catalog.

What to Include in Your RFQ

• Full part number and suffix (IS200EACFG1ABC), with a label photo if unsure of the exact revision
• Confirmation of the exciter's input voltage class (G1/G2/G3) if known
• Generator/turbine model and site
• Quantity and urgency

Request a Quote

We don't publish pricing or sell this board at checkout. Submit a Request a Quote with your part number and timeline and we'll respond within 24 hours with DDP pricing. We ship worldwide and accept purchase orders.