Description
Product Parameters
| Parameter | Specification |
|---|---|
| Brand / Series | GE Mark VIe Speedtronic |
| Model | IS200STTCH2A |
| Input Channels | 24 thermocouple inputs (software-configurable per channel) |
| Thermocouple Types | J, K, T, E, R, S, B (per-channel configurable via GE ToolboxST) |
| Input Range | ±100 mV |
| Cold-Junction Compensation | Built-in CJC sensor on terminal block (accuracy ±0.5°C) |
| ADC Resolution | 24-bit delta-sigma with programmable sampling rate (4–200 SPS) |
| Accuracy | ±0.1% of reading + ±1°C |
| Isolation | 1500 VAC (field-to-system) |
| Common Mode Rejection | >100 dB @ 50/60 Hz |
| Diagnostics | Open-circuit detection, short-circuit detection, CJC fault monitoring |
| Status Indication | 24 green LEDs (channel active), 2 red LEDs (diagnostic fault summary) |
| Operating Temperature | –30°C to +65°C |
| Mounting | VME rack-mount terminal board with front-panel I/O connector |
| Backplane Interface | VME64 (A24/A32, D16/D32) |
Advantages & Key Features
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High Channel Density: 24 thermocouple inputs in a single VME slot—triple the density of competing 8-channel thermocouple modules, ideal for turbines with extensive exhaust temperature monitoring (e.g., 24+ EGT thermocouples).
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Multi-Type Support: Supports J, K, T, E, R, S, and B thermocouple types, software-selectable per channel via GE ToolboxST, providing flexibility for different temperature ranges and sensor types.
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High-Precision Cold-Junction Compensation: Built-in CJC sensor near the terminal block with automatic compensation correction ensures measurement accuracy even during cabinet temperature fluctuations.
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24-Bit Delta-Sigma Conversion: High-resolution ADC with >100 dB CMRR delivers stable, noise-free readings in high-EMI environments typical of turbine generator halls.
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Programmable Sampling Rate: 4–200 SPS allows operators to trade speed for resolution based on application needs.
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Comprehensive Diagnostics: Real-time open-circuit, short-circuit, and CJC fault detection per channel enables predictive maintenance and prevents undetected sensor failures.
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ToolboxST Integration: Full configuration, calibration, and diagnostics via GE ToolboxST software.
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Drop-In Replacement: Direct replacement for earlier GE thermocouple boards such as IS200STTCH1A and IS200STTCH1.
Application Fields
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Gas & Steam Turbines (GE Frame 6B/7EA/9E/HA): Exhaust gas temperature (EGT) thermocouple arrays, turbine inlet temperature (TIT), bearing metal temperature, casing temperature, fuel gas preheat temperature.
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Combined Cycle Plants: HRSG superheater outlet temperature, reheat steam temperature, economizer inlet monitoring.
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Compressor Stations: Discharge gas temperature monitoring, intercooler performance tracking.
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Aeroderivative Turbines (LM series): Engine oil temperature, exhaust thermocouple arrays, fuel gas temperature.
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Industrial Process Monitoring: High-temperature process monitoring in petrochemical and refining applications.
Comparison with Competing Products
| Feature | GE IS200STTCH2A | Competitor A (Emerson 8CH TC) | Competitor B (Siemens 8CH TC) |
|---|---|---|---|
| Input Channels | 24 TC | 8 TC | 8 TC |
| Thermocouple Types | J, K, T, E, R, S, B | J, K, T | J, K, T, N |
| CJC Accuracy | ±0.5°C | ±1.2°C | ±1.0°C |
| ADC Resolution | 24-bit delta-sigma | 16-bit SAR | 16-bit sigma-delta |
| Accuracy | ±0.1% + ±1°C | ±0.2% + ±2°C | ±0.15% + ±1.5°C |
| Isolation | 1500 VAC | 1000 VAC | 500 VDC |
| Operating Temp | –30°C to +65°C | 0°C to 50°C | 0°C to 60°C |
Key Advantage: IS200STTCH2A provides triple the channel density (24 vs. 8) with superior CJC accuracy and higher ADC resolution compared to competing thermocouple modules. Its ability to mix multiple thermocouple types on the same board and comprehensive diagnostics make it the preferred choice for turbine exhaust temperature monitoring.
Selection Guidelines & Recommendations
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Thermocouple Type: Verify your thermocouple types. IS200STTCH2A supports J, K, T, E, R, S, and B—configure per channel in GE ToolboxST.
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CJC Sensor Placement: The CJC sensor is located on the terminal block—maintain adequate airflow around it; do not cover with heat-shrink or cable bundles.
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Sampling Rate: For steady-state temperature monitoring (exhaust, bearings), use 4–10 SPS for maximum accuracy. For dynamic tracking, use 50–100 SPS.
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Controller Firmware: Requires Mark VIe processor (e.g., IS420UCSBH1A, IS420UCSCH1A, IS200SPROH2ADD) firmware v7.0 or later.
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Wiring Guidelines: Use shielded thermocouple extension-grade leads with correct polarity. Maintain shield grounding only at the Mark VIe cabinet end.
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Spare Strategy: Keep one spare per turbine; lead times 6–10 weeks.
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Retrofit: Direct replacement for IS200STTCH1A and IS200STTCH1—regenerate configuration in GE ToolboxST.
Important Cautions
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No Hot-Swap: De-energize rack before insertion/removal.
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Thermocouple Polarity: Reverse connection produces negative readings—verify polarity against terminal labeling.
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CJC Protection: Do not apply conformal coating or tape over the terminal block area—this insulates the CJC sensor and invalidates compensation.
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Grounding: Connect AGND to Mark VIe system ground at single star point—multiple grounds degrade CMRR.
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Shield Termination: Thermocouple shields ground only at cabinet end to avoid ground loops.
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ESD Handling: Use grounded wrist straps; field repair not possible.
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Sampling Rate Trade-Off: Higher sampling rates reduce resolution—use lowest rate practical for steady-state monitoring.
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CJC Calibration: Factory-calibrated—do not attempt field calibration; requires specialized equipment.

GE UR1HH
AB 1769-IF8
A-B 1756-IF8
A-B 1771-OBN


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