The DS200TCTGG1A is a Turbine Trip Board designed by General Electric (GE) for its Mark V turbine control system. Belonging to the TCTG (Turbine Trip Board) series, this board is part of the G1 group and represents revision A (TCTGG1A). It is installed in the fourth position of the P1 core and serves as a critical component for implementing safe shutdown functions within the turbine control system.
The primary function of the DS200TCTGG1A board is to operate the turbine’s fuel shutoff valves, rapidly cutting off the fuel supply when abnormal conditions are detected to protect turbine equipment. This board integrates multiple trip logic mechanisms and redundancy protection schemes, including Primary Trip Relays (PTRs) and Emergency Trip Relays (ETRs), which employ hardware-level two-out-of-three (2/3) voting logic to ensure the reliability of trip commands. Additionally, the board incorporates generator breaker close circuits, synchronizing relays, and hardware trip pushbutton interfaces.
The DS200TCTGG1A board plays a vital safety protection role within the Mark V control system. It receives trip signals from the Control Sequence Program (CSP), TCEA boards, TCQA boards, and external hardwired trip pushbuttons. After processing these signals through multi-level redundant logic, it outputs trip commands to the fuel valves and generator breaker. The design of this board reflects GE’s strong commitment to safety and reliability in turbine control applications, making it suitable for critical rotating equipment such as gas turbines and steam turbines.
This product is widely used in power plants, petrochemical facilities, natural gas transmission, and other industrial sectors, particularly in turbine control applications with stringent safety shutdown requirements.
II. Key Functions
1. Primary Trip Relay (PTR) Control
The PTR relays are a core function of the DS200TCTGG1A board, used to execute trip operations when system faults are detected. PTR trip signals are driven by the TCQA board based on data generated by the Control Sequence Program (CSP). These signals are transmitted via the COREBUS to the I/O Engine in the R1 core. The STCA board in the R1 core then writes the trip signals across the 3PL connector to the TCQA board, which ultimately writes them to the TCTG board via the JD connector.
The PTR relays employ hardware-level two-out-of-three (2/3) voting logic. Even though the same signal is written to all three relays via the R1 core, a secondary hardware-level vote is performed to ensure the reliability of the trip command and resistance to single-point failures. Once a PTR trip is initiated, the CSP generates a cross trip signal that simultaneously triggers the ETR relays.
2. Emergency Trip Relay (ETR) Control
The ETR relays are controlled by the TCEA boards (X, Y, Z channels) located in the P1 core via the JLX, JLY, and JLZ connectors. The ETR relays also utilize hardware-level two-out-of-three (2/3) voting logic: if two out of the three relays call for a trip, the TCTG board triggers a system trip by opening and closing a series of related contacts.
The following signals will trigger ETR relay action:
High-pressure shaft overspeed and rapid deceleration
Low-pressure shaft overspeed and rapid deceleration
Cross trip (originating from a PTR trip)
The ETR trip signals are then written to the PTBA terminal board via the JM connector to execute the actual shutdown operations.
3. Generator Breaker Close Circuit
The DS200TCTGG1A board integrates generator breaker close control functionality. The close signals originate from:
STCA Board (R1 Core): Performs a synchronizing check (synch check) calculation and generates a permissive signal to close the breaker.
TCEA Boards (P1 Core): Use PT signals from the PTBA terminal board to perform automatic synchronizing calculations and generate a permissive signal to close the breaker.
The DS200TCTGG1A board performs a two-out-of-three (2/3) vote on the automatic synchronizing signals from the three TCEA channels. If two or three automatic synchronizing signals are valid and the synchronizing check signal from the R1 core has also been issued, the TCTG board sends a permissive signal to close the breaker to the PTBA board via the JN and JM connectors through relays K1, K2, and K3.
4. Manual and External Trip Circuit
The DS200TCTGG1A board supports hardwired connections to external trip devices. Normally closed contact inputs can be directly wired into the PTBA terminal board, triggering a trip when the contacts open. Emergency stop buttons are a typical example of such devices.
These external trip signals are read by the TCTG board via the JN connector and trigger relays K22, K23, K24, and K25 (referred to as the “4” relays, corresponding to the ANSI standard device number for Master Protective). When these relays are triggered, they de-energize the 24 V dc protective bus used by the PTR and ETR relays, causing them to initiate a trip.
The TCEA boards typically monitor hardware trip signals 1 through 3 to detect emergency stop events and record these events back to the Control Engine.
5. Hardware Trip Pushbuttons
Hardware trip pushbuttons can directly de-energize the 24 V dc power supply to both the PTR and ETR relays, achieving independent hardware-level tripping that does not rely on software logic, further enhancing system safety and reliability.
6. Synchronizing Relays
The DS200TCTGG1A board also integrates synchronizing relays for generator synchronization with the power grid, ensuring accurate closing timing and avoiding impact on both the generator and the grid.
7. Emergency Overspeed Servo Clamp Enable
The board features one hardware jumper (J1) used to apply 24 V dc to the servo outputs. When enabled, this jumper provides emergency overspeed servo clamp control for servovalves one through four. The actual relay for this function is located on the TCQC board.
III. Hardware Architecture
1. Board Structure
The DS200TCTGG1A board utilizes a standard printed circuit board structure and integrates:
Multiple Interface Connectors: For connections to the P1 core, R1 core, and external devices.
Hardware Jumpers: One configurable jumper (J1).
Relay Array: Including PTR relays, ETR relays, synchronizing relays, and “4” relays.
No Software Configuration: The TCTG board contains no software configuration; all functions are implemented through hardware logic.
2. Connector Description
| Connector | Function Description |
| J7W | Distributes 125 V dc power from the TCPD board in the P1 core. |
| JDR | Reads PTR trip signals from the TCQA board in the R1 core (relays K10, 13, 16, 19); reads synchronizing commands; reads generator and bus signals from the PTBA board; daisy-chained with JDS and JDT. |
| JDS | Reads PTR trip signals from the TCQA board in the R1 core (relays K11, 14, 17, 20); reads synchronizing commands; reads generator and bus signals from the PTBA board; daisy-chained with JDR and JDT. |
| JDT | Reads PTR trip signals from the TCQA board in the R1 core (relays K12, 15, 18, 21); reads synchronizing commands; reads generator and bus signals from the PTBA board; daisy-chained with JDR and JDS. |
| JLX | Reads ETR trip signals from the X channel in the P1 core; feeds ETR relays K5 and K8; supplies the 24 V dc protective bus. |
| JLY | Reads ETR trip signals from the Y channel in the P1 core; feeds ETR relays K4 and K7; supplies the 24 V dc protective bus. |
| JLZ | Reads ETR trip signals from the Z channel in the P1 core; feeds ETR relays K6 and K9; supplies the 24 V dc protective bus. |
| JN | Reads and writes signals to the PTBA terminal board in the P1 core, including breaker close signals, hardwire trip signals, and alarm horn signals. |
| JM | Reads and writes signals to the PTBA terminal board in the P1 core, including breaker close signals and emergency trip signals. |
| JT | Typically not used. |
3. Hardware Jumper
| Jumper | Name | Function |
| J1 | Emergency Overspeed servo Clamp Enable | Applies 24 V dc to the servo outputs for servovalves one through four (the actual relay is located on the TCQC board). |
4. Relay Description
| Relay Type | Designation | Function |
| PTR Relays | K10-K21 | Primary Trip Relays, triggered by CSP and communication faults. |
| ETR Relays | K4-K9 | Emergency Trip Relays, triggered by TCEA boards. |
| Synchronizing Relays | K1-K3 | Generator breaker close control relays. |
| “4” Relays | K22-K25 | Master Protective relays; cut off the 24 V protective bus during external hardwired trips. |
IV. Circuit Logic Details
1. ETR Relay Circuit
The ETR relay circuit is the core logic for implementing emergency trips on the TCTG board. The TCEA boards (X, Y, Z channels) in the P1 core send trip signals to the TCTG board via the JLX, JLY, and JLZ connectors. The ETR relays perform hardware-level two-out-of-three (2/3) voting:
Three TCEA channels respectively control the corresponding ETR relays.
If two or three relays call for a trip, the system triggers a trip by opening and closing a series of related contacts.
This hardware-level voting mechanism ensures that even if a single channel fails, the system can still correctly respond to trip conditions.
Conditions that trigger an ETR trip include:
High-pressure shaft overspeed
Low-pressure shaft overspeed
Rapid deceleration
Cross trip (originating from a PTR trip)
ETR trip signals are ultimately written to the PTBA terminal board via the JM connector to execute safety actions such as fuel cutoff.
2. PTR Relay Circuit
The PTR relay circuit handles trip signals generated by the Control Sequence Program (CSP). The signal flow is as follows:
The site-specific CSP generates a trip signal.
The signal is written to the I/O Engine in the R1 core via the COREBUS.
The STCA board in the R1 core writes the signal to the TCQA board via the 3PL connector.
The TCQA board writes the signal to the TCTG board via the JD connector.
Although the three PTR relays receive the same trip signal via the R1 core, the TCTG board still performs hardware-level two-out-of-three (2/3) voting to ensure the reliability of the trip command. Once a PTR trip is initiated, the CSP generates a cross trip signal that simultaneously triggers the ETR relays.
3. Generator Breaker Close Circuit
Generator breaker closure requires two conditions to be satisfied simultaneously:
Automatic Synchronizing Permissive: Calculated by the three TCEA channels (X, Y, Z) based on PT signals from the PTBA terminal board. The TCTG board performs a 2/3 vote on these signals.
Synchronizing Check Permissive: Calculated by the STCA board in the R1 core.
Only when both conditions are met does the TCTG board send a breaker close permissive signal to the PTBA board via relays K1, K2, and K3.
4. Manual and External Trip Circuit
External trip signals (such as emergency stop buttons) are hardwired to the PTBA terminal board. When a normally closed contact opens:
The JN connector reads this signal.
The TCTG board triggers relays K22-K25 (the “4” relays).
The “4” relays de-energize the 24 V dc protective bus used by the PTR and ETR relays.
The PTR and ETR relays lose power, triggering a system trip.
This design ensures that external trip signals are independent of software logic, achieving hardware-level independent safety protection.
V. Installation and Maintenance
1. Mounting Location
The DS200TCTGG1A board is installed in the fourth position of the P1 core, forming a core component of the Mark V control system together with other core boards.
2. Installation Steps
Verify Power is Off: Ensure the system has been de-energized and verify that no power exists on any circuits using high-voltage test equipment.
Locate the Board Slot: Confirm that the fourth slot of the P1 core is available.
Install the Board: Align the TCTG board with the slot guides and push it in smoothly until the backplane connectors are fully engaged.
Secure the Front Panel: Tighten the captive screws at the top and bottom of the front panel to secure the board.
Connect Cables: According to the system drawings, connect connectors J7W, JDR, JDS, JDT, JLX, JLY, JLZ, JN, JM, etc.
Configure Jumper: Set jumper J1 (Emergency Overspeed servo Clamp Enable) according to application requirements.
Power On and Verify: After powering on, verify normal board operation through system diagnostics.
3. Removal Steps
Verify Power is Off: Ensure the system has been de-energized and verify that no power exists on any circuits.
Label Cables: Label all cables with their connection positions before removal.
Disconnect Cables: Carefully disconnect all connectors.
Loosen Front Panel: Loosen the captive screws on the front panel.
Remove the Board: Gently pull out the TCTG board.
4. Maintenance Recommendations
Periodic Inspection: Regularly check board status and connector contact integrity.
Anti-Static Precautions: Always wear a grounded wrist strap when handling the board. Store the board in an anti-static bag when not in use.
Jumper Confirmation: When replacing a board, ensure the J1 jumper setting on the new board matches that of the old board.
Spare Parts Management: It is recommended to keep at least one identical TCTG board on-site as a spare to minimize downtime in case of failure.
VI. Applications
The DS200TCTGG1A Turbine Trip Board is widely used in the following industrial scenarios:
Gas Turbine Control: As a safety protection component in Mark V systems, executing fuel cutoff upon detection of overspeed, rapid deceleration, and other abnormalities.
Steam Turbine Control: Executing trip operations in steam turbine protection systems to prevent equipment damage.
Generator Protection: Working with generator breaker close circuits to achieve synchronization and protection for generator-grid connection.
Combined Cycle Power Plants: Serving as a core component of turbine protection systems in multi-shaft or single-shaft configurations.
Industrial Drive Systems: Providing safety protection functions in control systems for large compressors, pumps, and other rotating equipment.
