Quick Sizing & Sourcing Snapshot

• Manufacturer:​ GE (General Electric)
• Part Number:​ IS200ECTBG1A
• System Platform:​ EX2100 / EX2100e Excitation Control (Mark VI/VIe)
• Hardware Type:​ Exciter Contact Terminal Board (ECTB)
• Architectural Role:​ Provides the passive field termination for redundant trip relays and 70V DC wetted auxiliary contacts, interfacing the M1, M2, and C controllers via the EMIO board.
• Key Specifications:​ Redundant Mode Only, 2 Trip Relays, 6 Aux Inputs (70V DC), 3x 25-pin D-Sub​ to EMIO.

System Architecture & Operational Principle

The is a passive terminal board mounted in the EX2100 Exciter Cabinet, specifically designated for Redundant (TMR-style)​ architectures. It serves as the field-facing I/O hub for critical contact signals, bridging the turbine deck and the VME controllers.

Physically, it mounts to the cabinet frame. Upstream, it connects to the EMIO​ (Exciter Master I/O) boards in the M1, M2, and C cores via three 25-pin D-Sub connectors​ (J405 for M1, J408 for M2, J415 for C). Downstream, it handles the heavy lifting: it terminates six auxiliary contact inputs​ (powered/wetted by an isolated 70V DC​ supply from the EPSM via J13M1/J13M2) and hosts two heavy-duty Trip Relays​ (K1, K2). These relays typically drive customer lockout circuits or interface with the turbine’s TRLY (Trip Relay) boards. It also provides four General Purpose Form-C relays​ (K1GP-K4GP) controlled by the EMIO for auxiliary sequencing (e.g., field flashing). In a redundant setup, this board is replicated across the M1, M2, and C cores, ensuring that a wiring fault on the ‘M1’ physical terminal doesn’t disable the ‘M2’ or ‘C’ protection paths.

Core Technical Specifications

• Operation Mode:​ Redundant Only​ (G1 Suffix denotes Redundant; G2 is Simplex)
• Trip Outputs:​ 2x Form-C Relays (K1, K2), Driven by EMIO (24V/125V depending on config)
• General Relays:​ 4x Form-C (K1GP-K4GP), Customer Wired (Typically 125V DC)
• Auxiliary Inputs:​ 6x Contacts​ (Wetted by 70V DC​ from J13M1/J13M2)
• Monitored Inputs:​ 52G​ (Gen Breaker), 86G​ (Lockout) – 70V DC Wetting
• Controller Links:​ 3x 25-pin D-Sub (J405->M1, J408->M2, J415->C)
• Power Interface:​ J13M1 (M1 70V), J13M2 (M2 70V) from EPSM
• Terminals:​ TB1, TB2 (Barrier Strips for Field Wiring)
• Isolation:​ 500 V DC Channel-to-Earth (Relay Contacts)
• Indicators:​ Red LEDs​ per Input (State Indication), Relay Status (Implicit)
• Mounting:​ Chassis Mount (Exciter Cabinet)
• Environmental:​ 0°C to +60°C (Operational)

Customer Value & Operational Benefits

Redundant Path Integrity

The “G1” (Redundant) design ensures the M1, M2, and C​ controllers each get their own signal path from this single board. If a field wire chafes and shorts the “M1” 52G input at the terminal block, the M2 and C​ paths remain isolated due to the PCB layout and 70V DC sourcing. This preserves your 2oo3 Vote​ on Gen Breaker status, preventing a spurious trip or a “blind spot” during a real fault.

Centralized Protection Logic

By hosting the Trip Relays (K1/K2)​ here, you consolidate the final lockout drivers in one accessible location. Unlike rack-mounted VME cards, the ECTBG1A is front-accessible. You can megger the K1/K2​ contacts or verify 70V wetting on TB1 with the unit running (carefully), cutting troubleshooting time​ for “Trip Loop Failed” alarms.

Voltage Isolation for Wetting

The dedicated 70V DC​ wetting (via J13M1/J13M2) is a GE EX2100 standard. It prevents sneak paths from the 125V DC trip bus (on GP relays) from back-feeding into the 24V/5V logic of the EMIO. This isolation stops a field short on a 125V solenoid from frying the M1/M2/C processor’s input optos.

Field Engineer’s Notes (From the Trenches)

The “Gotcha” on the G1A is Mode Mismatch. This board is Redundant Only. If you try to plug this into a Simplex EX2100 setup expecting it to work like the G2 (Simplex) version, the EMIO software will flag “Architecture Mismatch” or “Loss of Vote” because it expects M1, M2, and C links (J405, J408, J415) and you only have M1 alive.

70V DC Sourcing​ is the next headache. The 6 Aux Inputs and 52G/86G require 70V DC​ wetted from the M1/M2 power supplies via plugs J13M1​ and J13M2. If J13M1 is loose or the M1’s 70V fuse is blown, M1’s inputs read open/false even if the field contact is closed. Always check ​ first when aux inputs are unresponsive.

Torque TB1/TB2. The Trip Relays (K1/K2) often switch 125V DC to the customer’s lockout. A loose “Common” creates an intermittent open; the turbine runs fine until vibration bumps the wire, opening the lockout circuit and tripping on “86G Actuated.” Use a 0.6 Nm driver, not finger-tight.