Description
It acts as the physical connection point where field-mounted thermocouple sensors terminate their signal wires to measure high-temperature metrics on gas, steam, or hydro turbines.
Commercial and Supply Chain Status
- Condition: New Original, New Surplus, or Refurbished (Fully Bench Tested and Validated)
- Warranty: 12-Month Comprehensive Industrial Warranty
- Availability: Active stock across global turbine asset support centers
- Lead Time: Ships within 2 to 4 business days from order confirmation
- Pricing: Price matches standard lifecycle curves for Speedtronic control line hardware; contact us for a firm quote.
Technical Specifications
| Parameter | Value |
| Manufacturer | General Electric (GE) |
| System Platform | Mark VI / Mark VIe Automation Core |
| Part Number | IS200STTCH2ABA |
| Functional Board Type | STTC (Thermocouple Terminal Board Assembly) |
| Channel Capacity | Supports up to 24 independent Thermocouple inputs |
| Terminal Block Layout | H2 Configuration: Features pluggable, removable right-angle terminal block headers |
| Cold Junction Sensors | Includes 2 redundant, onboard solid-state Cold Junction Compensation (CJC) sensors |
| Compatible I/O Packs | Connects to PTCH or VTCH processor packs via high-density cables |
| Hardware Revision | H2ABA (Denotes physical artwork layout, component updates, and functional backward compatibility) |
Functional Architecture and Cold Junction Compensation
The IS200STTCH2ABA aggregates high-density thermal monitoring loops directly onto the turbine control processing fabric.
- Cold Junction Compensation (CJC): Thermocouple sensors output microvolt-level signals based on the temperature delta between the hot probe tip and the cold terminal junction. To prevent ambient cabinet temperature shifts from introducing reading errors, the STTCH2 board features two redundant, onboard solid-state CJC sensors. These track the temperature at the terminal blocks, allowing the downstream I/O pack to dynamically normalize and correct the signal math.
- Open-Circuit Detection: Each individual channel contains a high-resistance pull-up resistor network. If a thermocouple wire breaks, burns out, or loses contact, the channel immediately pulls to the positive voltage rail. This triggers an instantaneous “Thermocouple Open Circuit” diagnostic alarm on the HMI to alert operators.
- Flexible Sensor Selection: The physical board hardware remains uniform across installations. Linearization for varying thermocouple types—including Type E, J, K, S, or T elements—is managed entirely via software mapping configurations loaded through the ToolboxST workspace.
Engineering Insights: Installation and Maintenance
Hardware Variant Differentiation (H1 vs. H2)
The H2 sub-string within STTCH2ABA designates that this board is equipped with removable, pluggable right-angle terminal blocks. This provides a massive advantage over the H1 configuration (which features permanently soldered terminal strips):
- During system upgrades or board failure swaps, the field wiring blocks can be unplugged as complete modules without disconnecting individual sensor wires.
- This drastically reduces replacement downtime and eliminates the risk of field wire landing errors.
Shield Termination and Extension Wire Matching
Because thermocouple signals operate in the millivolt range (mV), they are highly susceptible to electromagnetic noise generated by nearby generator lines or motor drives:
- Always use matching specialized thermocouple extension/compensation wire rather than standard copper hookup wire to bridge the gap between the field sensor and the panel.
- Ground the outer cable shields exclusively at the dedicated cabinet ground bar strip. Do not tie shields to common at both ends, as this creates ground loop currents that induce temperature reading fluctuations.
Frequently Asked Questions
Q: Can this terminal board be used directly in a Triple Modular Redundant (TMR) system? A: No. The STTC line is a Simplex terminal board designed to route signals back to a single I/O processor pack. For voted TMR turbine safety configurations (such as turbine exhaust gas temperature arrays), you must deploy the TTUR or TBRM terminal board variants instead.
Q: What is the cause of a constant “CJC Sensor Diagnostic Failure” alarm? A: This indicates that the onboard temperature reference circuits are tracking outside normal ambient parameters, or the tracking channel has failed. Because the system requires an accurate cold-junction reference to compute valid thermocouple values, a CJC failure will degrade channel accuracy across all 24 connected inputs.
Q: Is it necessary to recalibrate this hardware board following a standard component swap? A: No. The IS200STTCH2ABA relies on factory-set precision hardware and digital calibration data maintained on the primary I/O pack. Swapping the terminal board does not require manual potentiometer trimming or field calibration, provided the software choices inside your active ToolboxST project match the actual field sensor layout.
