The DS200DTBAG1A is a Contact Input Termination Module designed by General Electric (GE) Industrial Systems for its Mark V LM turbine control system. Belonging to the DTBA (Contact Input Termination Module) series, this module is part of the G1 group and represents revision A. It is installed in the sixth location of the digital I/O cores (<Q11>, <Q21>, and <Q51>), serving as the interface between field contact input signals and the control system.
The primary function of the DS200DTBAG1A terminal module is to connect contact input signals from field devices to the TCDA board within the digital I/O core. The module can accommodate up to 46 contact input channels and transmits these signals to the TCDA board for processing via the JQR connector. The module is powered by 125 V dc, which provides the interrogation voltage for the contact inputs, and utilizes hardware jumpers to isolate field grounds.
The DS200DTBAG1A module is designed to meet the demands of industrial field applications and features the following characteristics:
High-Density Input: Supports 46 contact inputs per module, saving cabinet space.
Electrical Isolation: Hardware jumpers allow isolation of field grounds, enhancing system reliability.
Flexible Configuration Options: Supports contact input inversion for failsafe functionality.
Modular Design: Works in conjunction with the DTBB expansion module to support up to 92 inputs.
Diagnostic Capabilities: Supports time-stamping of input state changes and fault diagnostics.
This product is widely used in power plants, petrochemical facilities, natural gas transmission, and other industrial sectors, particularly in turbine control applications requiring extensive discrete signal acquisition.
II. Key Functions
1. Contact Input Signal Acquisition
The core function of the DS200DTBAG1A module is to interface field device contact input signals (such as limit switches, pressure switches, temperature switches, pushbuttons, etc.) with the control system. The module supports up to 46 independent input channels, each connected to the TCDA board via the JQR connector. Input signals can be normally open (NO) or normally closed (NC) contact types, and signal inversion can be configured in software to meet failsafe design requirements.
2. Interrogation Voltage Supply
The module receives 125 V dc power from the TCPD board in the <PD> core via the J12 connector, providing the interrogation voltage for the contact input circuits. The interrogation voltage is distributed to individual input channels through BJ1-BJ5 hardware jumpers, forming a grouped power supply structure of 8 inputs per group. This design allows for troubleshooting by disconnecting groups one at a time to isolate ground faults.
3. Field Ground Isolation
The DS200DTBAG1A module provides field ground isolation functionality. Through BJ1-BJ5 hardware jumpers, the interrogation voltage can be disconnected from specific input groups, isolating field grounds from the system ground. This is particularly useful for troubleshooting ground faults, quickly identifying whether the fault is on the field side or the system side.
4. Time-Stamping
Each contact input state change is time-stamped with 1-millisecond accuracy by the processor on the TCDA board. These time-stamped events can be logged via the operator interface printer for Sequence of Events (SOE) recording and fault analysis.
5. Diagnostics and Alarms
The module supports continuous diagnostic testing. When a contact input circuit fault (such as an open circuit or short circuit) is detected, the system triggers a diagnostic alarm to alert maintenance personnel. Through the I/O Configurator, inversion masks and change detection masks can be set to customize input signal acquisition methods.
6. Cascading with DTBB Module
The DS200DTBAG1A module provides power and signal connectivity to the DTBB expansion module via the JY connector. The DTBA handles the first 46 inputs, while the DTBB handles the remaining 46 inputs, together forming a complete 92-channel contact input system.
III. Hardware Architecture
1. Module Structure
The DS200DTBAG1A module uses a standard printed circuit board structure designed for the Mark V LM control system core racks. The module includes:
46 Contact Input Terminals: For connecting field devices.
JQR Connector: Connects to the TCDA board for transmitting input signals.
J12 Connector: Receives 125 V dc power from the <PD> core.
JY Connector: Provides power and signals to the DTBB expansion module.
BJ1-BJ5 Hardware Jumpers: For grouped isolation of interrogation voltage.
JQS, JQT Connectors: Typically not used; reserved for future expansion.
2. Installation Location
The DS200DTBAG1A module is installed in the sixth location (Location 6) of the digital I/O cores (<Q11>, <Q21>, <Q51>). This location is positioned between the TCDA board (Location 1) and the DTBB board (Location 7), with signal transmission via backplane connections.
3. Power Supply
Main Power: 125 V dc, sourced from the TCPD board in the <PD> core via the J12 connector.
Distribution Method: Distributed to 5 input groups via BJ1-BJ5 jumpers, each group containing 8-10 channels.
Ground Isolation: Achieved through BJ1-BJ5 jumpers, isolating field grounds from the system ground.
4. Signal Flow
Field Contact Input → DTBA Terminals → JQR Connector → TCDA Board → IONET Network → TCQC Board → STCA Board → COREBUS → Control Engine
IV. Detailed Interface Description
1. JQR Connector
The JQR connector is the primary signal interface between the DTBA module and the TCDA board, transmitting 46 contact input signals to the TCDA board for preprocessing and acquisition. This is a 50-pin ribbon cable connector with signal allocation as follows:
| Signal Range | Description |
| CI 01-CI 10 | Contact Inputs 1-10 |
| CI 11-CI 20 | Contact Inputs 11-20 |
| CI 21-CI 30 | Contact Inputs 21-30 |
| CI 31-CI 40 | Contact Inputs 31-40 |
| CI 41-CI 46 | Contact Inputs 41-46 |
2. J12 Connector
The J12 connector receives 125 V dc power from the TCPD board in the <PD> core, providing the interrogation voltage for the contact input circuits. This is a 2-pin power connector with the following pin definitions:
| Pin | Signal | Description |
| J12-1 | +125 V dc | Positive power input |
| J12-2 | RTN | Power return |
3. JY Connector
The JY connector provides power and signal connectivity to the DTBB expansion module. The DTBA module transmits 125 V dc power and input signals to the DTBB module via the JY connector, enabling expansion to 46 additional inputs.
| Pin | Signal | Description |
| JY-1 | +125 V dc | Positive power output (to DTBB) |
| JY-2 | RTN | Power return (to DTBB) |
| JY-3 | Signal | Reserved |
| JY-4 | Signal | Reserved |
4. JQS, JQT Connectors
The JQS and JQT connectors are typically not used on the DTBA module and are reserved for future functional expansion.
5. Hardware Jumpers BJ1-BJ5
The BJ1-BJ5 jumpers are used for grouped isolation of contact input interrogation voltage. Each jumper controls the 125 V dc power supply for 8-10 input channels. The jumper positions and corresponding input channels are as follows:
| Jumper | Controlled Input Channels | Function |
| BJ1 | CI 1-9 | Isolate Group 1 interrogation voltage |
| BJ2 | CI 10-18 | Isolate Group 2 interrogation voltage |
| BJ3 | CI 19-27 | Isolate Group 3 interrogation voltage |
| BJ4 | CI 28-36 | Isolate Group 4 interrogation voltage |
| BJ5 | CI 37-46 | Isolate Group 5 interrogation voltage |
Jumper Setting Description:
IN (Shorted): Interrogation voltage connected to corresponding input channels (normal operation).
OUT (Open): Interrogation voltage disconnected from corresponding input channels (testing or troubleshooting only).
V. Hardware Configuration and Settings
1. Hardware Jumper Configuration
The BJ1-BJ5 jumpers on the DS200DTBAG1A module are factory-set to the IN position, meaning all input channels are connected to the interrogation voltage. These jumpers should only be changed in the following situations:
Ground Fault Troubleshooting: When a field-side ground fault is suspected, groups can be sequentially disconnected to isolate the fault location.
Testing Purposes: During module testing or calibration, certain groups may need to be disconnected.
Important Note: Changes to these jumpers should only be made when the turbine is not running to avoid safety issues caused by misoperation.
2. Software Configuration
Contact inputs on the DTBA module can be configured via the I/O Configurator, primarily including the following functions:
| Configuration Item | Description |
| Inversion Mask | Sets the logic inversion of input signals for failsafe applications. When the inversion mask is 1, an open NO contact corresponds to logic 1, and a closed NC contact corresponds to logic 1. |
| Change Detection Mask | Enables or disables input state change detection. When enabled, input state changes are recorded and generate Sequence of Events (SOE) records. |
3. Contact Input Wiring Examples
The following are typical contact input wiring methods:
| Contact Type | Wiring Method | Logic State |
| Normally Open (NO) | Contact closed = circuit closed | Logic 1 (no inversion) |
| Normally Closed (NC) | Contact open = circuit open | Logic 0 (no inversion) |
| Normally Open (NO) Failsafe | Contact closed = circuit closed | Logic 0 (with inversion mask) |
| Normally Closed (NC) Failsafe | Contact open = circuit open | Logic 1 (with inversion mask) |
VI. Installation and Maintenance
1. Pre-Installation Preparation
Ensure all power to the control system is turned off and verify that no power is present.
Verify that the sixth slot of the digital I/O core (<Q11>, <Q21>, or <Q51>) is available.
Prepare an anti-static wrist strap to prevent electrostatic damage to the module.
Confirm that field wiring has been completed according to drawings and checked for correctness.
2. Installation Steps
Verify Power is Off: Turn off all power to the drive, wait several minutes for all power supply capacitors to discharge, and test circuits to ensure power is off.
Open Cabinet Door: Access the printed wiring board area.
Locate the Slot: Confirm the sixth slot of the digital I/O core is available.
Insert the Module: Align the DS200DTBAG1A with the slot guides and push it in smoothly until the backplane connectors are fully engaged.
Secure the Front Panel: Tighten the captive screws on the front panel to secure the module.
Connect Cables:
Connect the JQR ribbon cable to the TCDA board.
Connect the J12 power cable to the TCPD board in the <PD> core.
If connecting a DTBB expansion module, connect the JY cable.
Configure Jumpers: Verify that BJ1-BJ5 jumper settings meet application requirements (default all IN).
Power On and Verify: After powering on, verify via the operator interface that the module is correctly recognized and communicating.
3. Removal Steps
Verify Power is Off: Ensure the system has been de-energized and verify that no power is present.
Disconnect Cables: Carefully disconnect all connectors (JQR, J12, JY).
Loosen Front Panel: Loosen the captive screws on the front panel.
Remove the Module: Gently pull out the DS200DTBAG1A module.
4. Maintenance Recommendations
Periodic Inspection: Regularly check terminal connections for tightness and wires for looseness.
Anti-Static Precautions: Always wear a grounded wrist strap when handling the module. Store the module in an anti-static bag when not in use.
Ground Fault Troubleshooting: In case of ground faults, use BJ1-BJ5 jumpers to isolate groups and systematically check field-side grounding issues.
Cleaning: Keep the module surface clean to prevent dust accumulation that could affect insulation performance.
Spare Parts Management: It is recommended to keep at least one identical DTBA module on-site as a spare to minimize downtime in case of failure.
VII. Applications
The DS200DTBAG1A Contact Input Termination Module is widely used in the following industrial scenarios:
Gas Turbine Control Systems: Acquiring signals from various protection switches, status switches, pushbuttons, etc., such as overspeed protection switches, lube oil pressure switches, fuel shutoff valve position switches.
Steam Turbine Control Systems: Acquiring discrete signals from steam turbine protection systems, such as vacuum switches, bearing temperature switches, shaft position switches.
Generator Protection Systems: Acquiring discrete signals from generator protection devices, such as differential protection operation signals, overcurrent protection operation signals.
Auxiliary Equipment Control Systems: Acquiring status signals from auxiliary equipment such as boilers, pumps, fans, including run/stop status and fault alarm signals.
Sequence of Events Recording Systems: Utilizing 1-millisecond time-stamp accuracy to record the sequence of critical events for fault analysis.
System Upgrade and Retrofit Projects: Replacing contact input modules in older systems with standardized interfaces and higher reliability.
