The IS200TRTDH1D is an RTD Input Terminal Board designed by General Electric (GE) for its Mark VIe Control System. This board is an important hardware revision within the TRTD series, primarily used to accept 16 three-wire RTD (Resistance Temperature Detector) inputs, providing precise temperature measurement signals for the control system. The IS200TRTDH1D board works in conjunction with PRTD I/O packs, utilizing two PRTD I/O packs to achieve acquisition and processing of 16 RTD signals.
The design of the IS200TRTDH1D boards the demands of industrial field applications. It features two barrier-type terminal blocks, each with 24 terminals, accepting up to #12 AWG wires. A shield terminal strip attached to chassis ground is located immediately to the left of each terminal block for connecting cable shields. The input circuits on the board feature noise suppression circuitry to protect against surges and high-frequency noise, ensuring the accuracy and stability of measurement signals.
Key features of the IS200TRTDH1D include:
16 RTD Inputs: Supports three-wire RTDs, capable of measuring various RTD types.
Coordination with PRTD: Two PRTD I/O packs plug directly into the board, each handling 8 inputs, totaling 16.
Long-Distance Measurement: RTDs can be located up to 300 meters (984 feet) from the control cabinet, with a maximum two-way cable resistance of 15 Ω.
Excitation Current: Provides 10 mA dc multiplexed (non-continuous) excitation current, supporting grounded or ungrounded RTDs.
Noise Suppression: All RTD signals have high-frequency decoupling to ground at signal entry.
Fault Detection: Can detect RTD open circuits, short circuits, and out-of-hardware-limit conditions.
Automatic Calibration: Uses filtered calibration source and null voltages for automatic calibration.
Multiple RTD Types: Supports platinum, copper, nickel, and other RTD materials, covering a wide temperature range.
ID Chip Identification: The board features an ID chip read by the PRTD to ensure hardware compatibility.
Redundant Pacemaker Coordination: RTD multiplexing in the PRTD is coordinated by redundant pacemakers, ensuring that the loss of a single cable or PRTD does not cause the loss of any RTD signals in the control database.
The board operates within a temperature range of -30 to 65°C (0 to 60°C when used with PRTD), suitable for industrial control cabinet environments. It is important to note that the TRTDH1D only supports simplex systems and is not applicable for TMR applications.
II. Main Functions
The primary functions of the IS200TRTDH1D include, but are not limited to, the following:
1. RTD Signal Acquisition
The IS200TRTDH1D board provides 16 three-wire RTD input channels for acquiring signals from various field temperature sensors. Each RTD connects to the two terminal blocks on the board via three wires: excitation positive, signal positive, and common.
2. Excitation Current Supply
The board, via the PRTD I/O packs, supplies a 10 mA dc multiplexed (non-continuous) excitation current to each RTD. This design reduces power consumption and self-heating effects, improving measurement accuracy. RTDs can be either grounded or ungrounded, adapting to different field installation conditions.
3. Long-Distance Measurement Support
RTDs can be installed at locations remote from the control cabinet, up to a maximum distance of 300 meters (984 feet), with a maximum two-way cable resistance of 15 Ω. This feature allows RTDs to be flexibly deployed at various measurement points in the industrial field without requiring the control cabinet to be located near the equipment under test.
4. Signal Conditioning and Noise Suppression
All RTD signals undergo high-frequency decoupling upon entering the board, effectively suppressing high-frequency noise interference. The input circuits on the board also provide surge protection, ensuring signal integrity in harsh industrial environments.
5. Analog-to-Digital Conversion and Scanning
The A/D converter in the PRTD I/O pack samples each signal and the excitation current at a time interval related to the power system frequency:
6. Linearization Processing
The processor in the PRTD performs linearization of the RTD signals via software, supporting 15 RTD types, including platinum, copper, nickel, and other materials, covering a wide temperature range from -60 to 1616°F.
7. Fault Detection
RTD open and short circuits are detected by out-of-range values. When an RTD is determined to be outside the hardware limits, that input channel is removed from the scanned inputs to prevent adverse effects on other input channels. Repaired channels can be reinstated automatically after 20 seconds or can be manually reinstated.
8. Redundant Pacemaker Coordination
RTD multiplexing in the PRTD is coordinated by redundant pacemakers, ensuring that the loss of a single cable or PRTD does not cause the loss of any RTD signals in the control database. This design significantly enhances system reliability.
9. Automatic Calibration
RTD input channels are automatically calibrated using the filtered calibration source and null voltages, ensuring long-term measurement accuracy and reducing on-site calibration maintenance.
10. ID Chip Identification
The board features a read-only ID chip storing the board's serial number, type, revision number, and connector location information. The PRTD reads this information during initialization. If a mismatch is encountered, a hardware incompatibility fault is generated, preventing system problems caused by incorrect configuration.
III. System Applications
1. Application in Mark VIe Control System
The IS200TRTDH1D is a key terminal board for temperature measurement within the Mark VIe control system, widely used for temperature monitoring in gas turbines, steam turbines, generators, and other equipment. Working with the PRTD I/O pack, it forms a complete RTD input subsystem.
In the system, IS200TRTDH1D plays the following roles:
Temperature Monitoring: Acquires critical temperature points such as bearing temperature, exhaust temperature, and cooling medium temperature.
Process Control: Provides feedback signals for temperature control loops.
Protection Functions: Provides input signals for overtemperature protection.
Performance Monitoring: Acquires temperature parameters for efficiency and performance calculations.
2. Coordination with PRTD
The IS200TRTDH1D board features two DC-37 pin connectors for inserting two PRTD I/O packs respectively. Each PRTD handles 8 RTD inputs, with two PRTDs handling all 16 inputs. This design offers flexible configuration options:
One PRTD can handle the first 8 inputs, and the other PRTD handles the last 8 inputs.
The two PRTDs operate independently; a failure in one does not affect the inputs of the other.
Redundant pacemaker coordination ensures that the loss of a single cable or PRTD does not cause the loss of any RTD signals.
3. Differences from the H1C Version
Compared to the H1C version, the main improvements in the IS200TRTDH1D are:
Enhanced Redundancy Feature: RTD multiplexing in the PRTD is coordinated by redundant pacemakers, ensuring no signal loss from single point failures.
Broader RTD Type Support: Supports a wider range of RTD linearization types.
Improved Compatibility: Compatible with newer PRTD firmware revisions.
4. Typical Application Scenarios
Gas Turbines: Monitoring compressor inlet/outlet temperatures, combustion chamber temperature, exhaust temperature, bearing temperatures, etc.
Steam Turbines: Monitoring main steam temperature, reheat steam temperature, extraction steam temperature, bearing temperatures, etc.
Generators: Monitoring stator winding temperature, core temperature, cooling medium temperature, bearing temperatures, etc.
Heat Recovery Steam Generators (HRSG): Monitoring flue gas temperature and steam temperature in various sections.
Auxiliary Equipment: Monitoring oil system temperature, cooling water system temperature, etc.
IV. Detailed Interface Description
1. Terminal Blocks
The IS200TRTDH1D board features two barrier-type terminal blocks, each with 24 terminals, for connecting the 16 three-wire RTDs. Each RTD uses three terminals:
2. Shield Terminal Strips
A shield terminal strip attached to chassis ground is located immediately to the left of each terminal block. These are used for terminating the shields of RTD cables to reduce electromagnetic interference. Double-shielded wire must be used. All shields must be terminated at the shield terminal strip. Do not end shields at the end device.
3. I/O Pack Connectors
The board features two DC-37 pin connectors for directly plugging in the PRTD I/O packs. Each connector contains 8 RTD input signals, ID signal, relay coil power, and feedback multiplex command. These two connectors correspond to two groups of 8 inputs each.
4. Power Supply
The PRTD I/O pack accepts 28 V dc power via a 3-pin power connector on its side, powering both the I/O pack and the terminal board.
V. Diagnostics and Maintenance
1. Diagnostic Functions
The IS200TRTDH1D provides the following diagnostic functions via the PRTD I/O pack:
| Diagnostic Item | Description |
| Hardware Limit Check | Each RTD type has preset hardware high/low limits. Exceeding limits stops scanning the channel and sets a logic signal. Any channel exceeding limits generates the L3DIAG_PRTD composite diagnostic alarm. |
| System Limit Check | Each RTD input has system limit checking based on configurable high/low levels, which can be used to generate alarms and configured as latching or non-latching. |
| ID Chip Verification | The PRTD reads the board's ID chip and compares it with the configuration. A mismatch generates a hardware incompatibility fault. |
| Power-Up Self-Test | Includes checks of RAM, Flash memory, Ethernet ports, and most of the processor board hardware. |
| Internal Power Supply Monitoring | Continuously monitors internal power supplies for correct operation. |
| Electronic ID Check | Checks electronic ID information from the terminal board, acquisition board, and processor board to confirm that the hardware set matches. |
2. Fault Handling
When a channel exceeds hardware limits, it is removed from the scanned inputs to prevent affecting other channels.
Repaired channels can be automatically reinstated after 20 seconds or manually reinstated.
Diagnostic signals can be individually latched and reset with the RESET_DIA signal after returning to normal.
System limit out-of-range signals can be reset with RESET_SYS.
3. Common Troubleshooting
| Fault Symptom | Possible Cause | Troubleshooting Suggestions |
| No reading on a channel | RTD open circuit, wiring error, channel fault | Check RTD and wiring, measure RTD resistance |
| Reading abnormally high/low | Incorrect RTD type configuration, excessive lead resistance | Check RTD type configuration, check cable resistance |
| Reading fluctuating or unstable | Poor shield grounding, electromagnetic interference | Check shield grounding, check cable routing |
| L3DIAG_PRTD composite diagnostic alarm | A channel has exceeded limits | Identify the specific fault channel, check the corresponding RTD and measurement point |
| Hardware incompatibility fault | ID chip information mismatch | Verify correct board model, contact GE technical support |
4. Maintenance Recommendations
Periodic Inspection: Check terminal blocks for looseness and wires for oxidation.
Cleaning: Regularly clean the board to prevent dust accumulation affecting heat dissipation and insulation.
ESD Protection: Wear a grounding strap when handling the board and store it in anti-static bags.
Spare Parts Management: Maintain spare IS200TRTDH1D boards and PRTD I/O packs to reduce downtime in case of failure.
VI. Installation and Configuration
1. Installation Steps
Mount Terminal Board: Securely mount the IS200TRTDH1D board in the cabinet using screws.
Connect RTD Wires: Connect the three wires of each RTD to the corresponding terminals on the terminal blocks. Use double-shielded cable; terminate all shields at the shield terminal strips.
Install PRTD I/O Packs: Plug one or two PRTD I/O packs directly into the board's DC-37 pin connectors.
Secure I/O Packs: Mechanically secure the packs using the threaded inserts adjacent to the Ethernet ports. The inserts connect with a mounting bracket specific to the terminal board type. Adjust the bracket location so that there is no right-angle force applied to the DC-37 pin connector between the pack and the terminal board.
Connect Ethernet: Plug in one or two Ethernet cables. If dual connections are used, the standard practice is to connect ENET1 to the network associated with the R controller.
Connect Power: Apply 28 V dc power to the I/O pack via the 3-pin power connector on its side.
Configure I/O Packs: Use the ToolboxST application to configure the I/O packs as necessary.
2. Configuration Parameters
The following parameters can be configured via ToolboxST software:
| Parameter | Description | Choices |
| SystemLimits | Temporarily disable all system limit checks for testing purposes | Enable (default), Disable |
| Auto Reset | Automatic restoring of RTDs removed from scan | Enable (default), Disable |
| GroupRate | RTD 1-8 sample rate and system frequency filter | 4 Hz, 50 Hz filter; 4 Hz, 60 Hz filter (default); 25 Hz |
| RTD Type | Select RTD type | Unused, CU10, PT100_DIN, PT100_PURE, PT100_USIND, N120, PT200, etc. |
| SysLim1/2 Enabl | Enable system limit fault check | Enable, Disable (default) |
| SysLim1/2 Latch | Latch system limit fault | Latch (default), Unlatch |
| SysLim1/2 Type | System limit check type | ≥ (default), ≤ |
| System Limit 1/2 | Set limit temperature value | -60 to 1300 (default) |
