The DS200TCQCG1BBA is an Analog IO Expander Board (TCQC) manufactured by GE Energy as part of the Mark V™ LM turbine control system. This board is a signal conditioning and interface module installed within the I/O cores (<R1>, <R2>, and <R3>). The TCQC board expands the analog input/output capabilities of the system by providing additional channels for servo valve control, pulse rate measurement, generator and line feedback, LVDT/LVDR excitation, and IONET termination. It interfaces with multiple terminal boards (QTBA, TBQB, TCQE, TCEA, etc.) and communicates with the STCA board through several dedicated connectors.
The DS200TCQCG1BBA is designed for reliable operation in demanding industrial environments. It receives power from the TCPS power supply board via the 2PL connector and distributes conditioned signals to and from various system components. The board is configured entirely by hardware jumpers; there is no software configuration. The suffix BBA indicates a specific revision and factory configuration (including component selection, coating, and jumper presets) that ensures full backward compatibility with all Mark V LM systems while incorporating the latest design improvements.
This board is essential for turbine control applications requiring precise servo valve positioning, speed sensing, generator synchronisation, and position feedback from LVDT/LVDR sensors.
Functional Description
The DS200TCQCG1BBA performs several critical functions within the Mark V LM control system:
Servo Valve Regulator Output – The board receives current commands from the TCQA board via the JE connector. These signals are scaled by hardware jumpers on the TCQC board and sent to the QTBA terminal board via the JFF connector to position the servo valves. The board contains servo clamp relays and suicide relays. Energizing the suicide relays drives the servo signal to ground, allowing the valve to drift to its bias position. Energizing the servo clamp relays applies a positive current to the valve. Suicide relay activation is controlled by a signal from the Control Sequence Program (CSP) via TCQA, while emergency signals from the TCEA board directly energize the clamp relays.
Pulse Rate Input – The board reads high‑pressure shaft pulse rate signals from the TCQE board (via the JJ connector). These signals originate on the PTBA board in the <P1> core. The pulse rate data is passed to the TCQA board via the JE connector for scaling and conditioning, then written to the STCA board via the 3PL connector. Additional magnetic pickup and TTL pulse rate signals from the TBQB terminal board are read through the JH connector. Additional magnetic pickup signals are also available on the QTBA board and read via the JGG connector.
Generator and Line Feedback – The board scales and conditions generator and line feedback signals that originate on the TCTG board in the <P1> core. These signals pass through the TCQA board and are written to the TCQC board via the JE connector. The conditioned signals are then sent to the STCA board via the 19PL connector for use in the synchronisation check (synch check) function.
IONET Termination – In the <R1> core, the TCQC board terminates the IONET daisy‑chain from the TCEA boards (<X>, <Y>, <Z>) in the <P1> core and the TCQA board in the <Q1> core. The signals are written directly to the STCA board via the 8PL connector.
LVDT/LVDR Excitation – The board generates a 3.2 kHz, 7 V rms excitation signal for LVDT and LVDR position sensors. This excitation is delivered to the QTBA terminal board via the JFF connector.
4–20 mA Input – The board provides circuitry for two mA input signals. The first (typically compressor stall detection) is read from the TBQB terminal board via the JH connector. The second (typically megawatt transducer) is read from the QTBA terminal board via the JGG connector. Both signals are written to the STCA board via the 19PL connector.
Hardware Characteristics
The DS200TCQCG1BBA is a printed wiring board conforming to the Mark V LM 6U Eurocard form factor (approximately 233 mm × 160 mm). It is inserted into the designated slot (location 3) in the <R1>, <R2>, or <R3> core’s card cage. The board is secured by faceplate screws and includes ejector tabs for easy removal.
Connectors
Connector | Type | Description |
2PL | Ribbon cable connector | Distributes power from the TCPS board in the core to the TCQC board. |
8PL | Multi‑pin connector | I/O connection to the STCA board; carries COM1 RS232, serial I/O, AC/DC power monitoring, and a pulse rate magnetic pickup signal. |
19PL | Multi‑pin connector | I/O connection to the STCA board; carries megawatt, generator, bus, compressor stall detection, and high‑pressure shaft pulse rate signals. Also carries power bus and neutral bus signals. |
JC | Multi‑pin connector | Receives power supply diagnostic signals from the TCPS board; passes them to TCQA (via JE) and STCA (via 19PL). |
JE | Multi‑pin connector | Writes power supply monitoring signals to TCQA; reads servo valve outputs and generator/line signals from TCQA. |
JFF | Multi‑pin connector | Writes servo outputs and LVDT/LVDR excitation to the QTBA terminal board. |
JGG | Multi‑pin connector | Writes servo outputs and 15 A signals; reads magnetic pickup and megawatt transducer signals from QTBA. |
JH | Multi‑pin connector | Reads pulse rate and compressor stall signals from the TBQB terminal board. |
JJ | Multi‑pin connector | Reads speed signals from the TCQE board in <R1> (originating on PTBA in <P1>). |
JX | Multi‑pin connector | Terminates the IONET signal from TCEA boards in <P1>; used only in <R1> core. |
1PL, 6PL, 17PL | Not used | Typically not connected. |
VARC, JBU, ARCPL, CARC | Not used | Typically not connected. |
Jumpers and Configuration
The DS200TCQCG1BBA is configured entirely by hardware jumpers. There is no software configuration.
Jumper Group | Function |
J1–J16 (even numbered) | Select feedback scaling for servo outputs. |
J1–J16 (odd numbered) | Select source output resistance for servo outputs. |
J25–J36 | Additional feedback scaling options for servos 1–4, enabling a maximum current range of ±240 mA. |
BJ17 | Enables the RS232 port for card tests. |
BJ21 | Enables the stall timer. |
BJ22 | Enables the oscillator for factory test. |
BJ23, BJ24 | Not used. |
BJ18, BJ20 | Limit the P15 and N15 supply to proximity transducers. |
JP38, JP39 | Set the magnetic pickup gain for liquid fuel flow signals in some applications. |
The output current range for servo valves is configured by these jumpers, allowing flexibility for different actuator requirements. The board also includes servo clamp and suicide relays that are controlled by hardware logic.
Installation and Replacement
Handling Precautions
Static sensitivity – The DS200TCQCG1BBA contains static‑sensitive components. Always wear a wrist grounding strap and handle the board at a grounded workstation. Store the board in its antistatic bag when not in use.
De‑energise before handling – Turn off power to the core (using the corresponding switch on the TCPD board in the <PD> core) and verify zero voltage before touching the board or any connected cables. Follow all local lock‑out/tag‑out procedures.
Do not insert or remove with power applied – Doing so may cause equipment damage or personal injury.
Replacement Procedure
De‑energise the core where the DS200TCQCG1BBA is installed.
Open the cabinet door and test for zero voltage on all circuits.
Label and disconnect all cables from the TCQC board (2PL, 8PL, 19PL, JC, JE, JFF, JGG, JH, JJ, JX, and any others).
Loosen the top and bottom captive screws and use the ejector tabs to unseat the board.
Remove the board from the card cage.
Before installing the replacement board, verify that all jumpers are set to the same positions as on the original board (critical for correct servo scaling and functionality). Refer to the site‑specific hardware jumper documentation.
Slide the replacement DS200TCQCG1BBA into the correct slot (location 3 in <R1>, <R2>, or <R3>) and press firmly to seat it.
Tighten the faceplate screws evenly.
Reconnect all cables in the reverse order.
Restore power to the core and verify that the board is recognised by the control system (no diagnostic alarms).
When ordering the DS200TCQCG1BBA, use the complete part number exactly as shown. The part number follows GE’s convention:
DS200 – Drive / Control series.
TCQC – Functional acronym: Analog IO Expander Board.
G1 – Generation/version.
B – Base designator.
B – Modifier (e.g., coating, component variation, or special configuration).
A – Revision A.
Warranty and Order Placement
Note: All digits and letters in the part number are significant. GE may substitute later compatible revisions, but backward compatibility is assured.
Diagnostics and Maintenance
The DS200TCQCG1BBA does not have onboard diagnostics beyond the signals it passes. Its health is monitored by the STCA and TCQA boards. The control system (via ToolboxST) provides diagnostic alarms for:
Loss of communication with the TCQC board (via 8PL or 19PL).
Servo output current mismatch or suicide relay activation.
Pulse rate input loss or out‑of‑range signals.
Generator/line feedback signal loss.
IONET termination faults.
No routine calibration is required. However, if the board is replaced, the hardware jumper settings must be verified against the site‑specific configuration. Periodic inspection for dust, corrosion, or loose connections is recommended.
