Description

GE IS200STTCH2ABA

I. Basic Information

Model: IS200STTCH2ABA (abbreviated as STTC), belonging to the Speedtronic Mark VI/VIe gas turbine control system. It is a dedicated simplex terminal I/O board for thermocouple application, matched with PTCC/VTCC thermocouple master processor cards. The board performs field wiring connection and preconditioning of thermocouple signals installed on gas turbine casing, exhaust ducts and bearings. As standard spare parts for temperature acquisition of gas & steam turbines, it is compatible with three system architectures including TMR triple modular redundancy, dual redundancy and simplex configuration. Widely used for retrofit replacement of obsolete GE gas turbine control systems in power plants, it supports 24/7 continuous in-cabinet operation.

Product Positioning: A field thermocouple terminal board integrating signal conditioning and onboard cold-junction compensation. It serves as a compact DIN-rail mounted alternative to bulky TBTC terminal boards. After receiving signals from various field thermocouple sensors and finishing preprocessing, converted data is transmitted via backplane or ribbon cables to PTCC processor cards for A/D conversion and physical temperature calculation.

II. Technical Specifications

(1) Basic Hardware Specifications

Brand: GE General Electric | Origin: USA
Product Type: Simplex Thermocouple Terminal Acquisition Board (STTC)
Compatible Systems: Speedtronic Mark VI & Mark VIe gas turbine DCS, coordinated with PTCC (for VIe) / VTCC (for VI) processor boards
Mounting: Standard DIN35 rail installation inside control cabinet
Dimension: 150mm(D)×120mm(W)×50mm(H), Net Weight: 0.4kg
Protection Rating: IP20 (cabinet-mounted)
Hardware Structure: Full SMD multi-layer PCB equipped with onboard hardware ID chip; the host processor automatically identifies board model after power-up without DIP switch setting.
Terminals: Removable high-density European screw terminals with partitioned layout to avoid miswiring.

(2) Rated Electrical Specifications

Power Supply: Centralized DC24V feed from I/O backplane; total power consumption ≤6W
Input Channels: 8 independent thermocouple input channels
Millivolt Input Range: -8mV～+45mV, matching thermoelectric output of all standard thermocouple types
Channel Isolation: Optocoupler isolation per single channel; short-circuit or open-circuit on one thermocouple will not affect signal acquisition of the whole board.
Cold-Junction Compensation: Onboard high-precision cold-junction temperature sensor automatically compensates ambient temperature drift at terminal side and eliminates measurement error induced by cold-end temperature variation.

(3) Thermocouple Compatibility Specifications

Supports all mainstream industrial thermocouple calibrations: K, J, T, E, R, S, B, N, covering full measurement points of turbine exhaust, casing and bearing temperature.

Measurement Accuracy: Full-scale error ≤±0.1% FS after cold-junction compensation
Open-Circuit Detection: Automatically sends fault codes to Mark VIe upper monitoring software once any thermocouple channel is open-circuited.

(4) Communication Interface Specifications

The board connects to PTCC/VTCC processor cards via dedicated ribbon cables and transmits digitized temperature data over 100Mbps IONet industrial Ethernet. It supports EGD protocol and IEEE1588 time synchronization, delivering millisecond-level data to gas turbine controllers for interlock protection logic calculation.

(5) Environmental Specifications

Operating Temperature: -40℃～+70℃ (in-cabinet operation)
Storage Temperature: -40℃～+85℃ (transportation & storage)
Operating Humidity: 5%～95% RH (non-condensing). Resists dust, oil mist and variable-frequency electromagnetic interference in power plant control rooms and complies with IEC61000 industrial EMC standards.

III. Key Features

Onboard Cold-Junction Compensation Eliminates External Compensation Boxes

Integrated factory-designed cold-junction measuring circuit corrects real-time temperature deviation caused by ambient change at terminal blocks, ensuring accurate thermocouple reading and reducing extra auxiliary components inside cabinets.

8 Independently Isolated Channels to Prevent Full-Board Failure from Single-Point Fault

Each thermocouple input features isolated circuit design; short circuit or damaged wiring of one field probe only triggers single-channel fault alarm while the remaining seven channels keep normal acquisition, securing uninterrupted critical temperature monitoring for gas turbines.

Universal for All Thermocouple Types with Flexible Software Configuration

Users can configure thermocouple type for each of the 8 channels via software on one single board. Mixed installation of K/J/T/E sensors is available to satisfy diversified measuring point requirements on gas turbines.

Intelligent Open-Circuit Diagnosis Enables Fast Fault Localization

Automatic identification of broken or open thermocouple cables, with local board LED and upper HMI synchronously indicating faulty channel to shorten on-site troubleshooting duration.

Compact DIN-Rail Design Optimizes Cabinet Layout

Much smaller footprint compared with conventional large-size TBTC terminal boards; multiple STTC modules can be mounted side-by-side on DIN rail for dense measuring point layout to save cabinet slot space.

Pin-to-Pin Drop-in Replacement

Different STTC revisions including IS200STTCH2A/2ABA share identical pinout and terminal definition. Faulty legacy boards can be directly hot-swapped without modifying field thermocouple wiring or control configuration.

IV. Working Principle

Power-on Self-test: Upon DC24V energization, the board runs self-diagnosis on channel circuits, ID chip and cold-junction sensing circuit, then completes handshaking and registration with PTCC processor after successful check.
Millivolt Signal Acquisition: Field thermocouple sensors are wired to terminals, feeding thermoelectric millivolt signals into onboard signal conditioning circuits.

Cold-End Temperature Correction: The module samples ambient terminal temperature and automatically calculates compensation value based on standard thermocouple characteristic formulas to offset cold-junction drift.
Signal Preprocessing: Filtering and amplification are performed before signals are transferred via ribbon cable to PTCC master card for A/D conversion and actual temperature calculation.
Data Upload & Fault Reporting: Valid temperature values are packed and uploaded to Mark VIe controller via IONet for interlock logic execution; open-circuit or over-range faults are simultaneously alerted on upper monitoring system.
Cyclic Operation: The board repeats continuous sampling, compensation and data transmission to monitor unit temperature parameters round the clock.

V. Application Scenarios

(1) Gas Turbine Body Temperature Monitoring (GE 9F/6FA/5E and equivalent units)

Thermocouple collection for combustor exhaust, turbine blade exhaust, bearing bush and casing shell, participating in over-temperature trip interlock and closed-loop temperature control.

(2) Steam Turbine Generating Units

Temperature measurement for turbine casing, bearing pads and reheated steam pipelines, cooperating with Mark VIe excitation and governor control systems.

(3) Waste Heat Units at Captive Power Plants of Coal-Chemical & Steel Plants

Flue gas temperature detection for gas turbines and waste heat boilers to implement process over-temperature interlock protection.

(4) Retrofit & Spare Replacement for Obsolete GE Gas Turbine Control Systems

Replacement of aging defective STTC/TBTC terminal boards and expansion of temperature measuring points without rewiring field secondary thermocouple cables.