GE IS200TBCIH1C Contact Input Terminal Board

General Specifications

• Product Type: Contact Input Terminal Board (TBCI)

• Manufacturer: General Electric

• Series: Mark VI / Mark VIe Speedtronic System

• Functional Category: Digital Contact Input Terminal Board

• System Architecture Support: Simplex and TMR (Triple Modular Redundancy)

• Manual Reference: GEH-6421J

• Country of Manufacture: United States

Input Specifications

• Number of Channels: 24 dry contact input channels

• Input Type: Dry contacts (NO/NC), passive switch signals

• Excitation Voltage: 125 V DC (floating supply from turbine control)

• Excitation Range: 100-145 V DC

• Input Configuration: 2 groups of 12 channels

• Terminal Blocks: Two barrier-type terminal blocks, removable for maintenance

• Terminal Capacity: Accepts wire up to #12 AWG

• Input Current Loading: 2.5 mA per point for first 21 inputs; 10 mA for last 3 inputs (supports external solid-state output devices)

Power Specifications

• Power Consumption: Maximum 20.6 watts

• Isolation Voltage: 1500 V AC (channel-to-system isolation)

• Signal Processing: Hardware filtering, surge suppression, noise suppression, contact debouncing

Environmental Specifications

• Operating Temperature: -30°C to +65°C (some sources indicate -40°C to +85°C range)

• Storage Temperature: -40°C to +85°C

• Humidity: 5% to 95% non-condensing

• Protection Rating: IP20

• Vibration Resistance: Designed for NEMA Class G creepage and clearance

Physical Characteristics

• Dimensions: Approximately 172.7 mm × 114.3 mm × 20 mm or 120 mm × 80 mm × 40 mm (variance by source)

• Weight: Approximately 0.2 kg to 0.45 kg

• Mounting: Mark VI rack installation via VME chassis

• Connectors: JR1, JS1, JT1 for simplex and TMR cabling connections

Communication & Diagnostics

• Status Indicators: LED indicators for power and channel status

• Diagnostics: Excitation voltage monitoring, input fault detection, TMR voting verification, connector ID validation

• Connector Identification: Read-only chip containing serial number, board type, revision number, and connector location information

Functional Features

High-Density 24-Channel Contact Input
The terminal board integrates 24 dry contact channels into a single board, allowing centralized acquisition of external switch signals including valve position feedback, pump status, emergency stop inputs, limit switches, and circuit breaker status . This high-density design simplifies system wiring and reduces cabinet space requirements.

Industrial-Grade Signal Protection
The module incorporates comprehensive protection circuitry including MOV/TVS surge suppression, EMI/RFI high-frequency filtering, and hardware contact debouncing circuits . These features effectively filter out electromagnetic interference and contact bounce common in turbine compartments, ensuring stable signal acquisition without false readings.

Robust Electrical Isolation
The IS200TBCIH1C provides 1500 V AC channel-to-system isolation, preventing field ground potential differences, surges, and short circuits from damaging controller I/O modules . This isolation significantly enhances system safety and noise immunity in demanding industrial environments.

TMR Redundancy Compatibility
The board fully supports the Mark VI Triple Modular Redundancy architecture, enabling 2oo3 (two-out-of-three) voting logic . Single-point channel failures do not affect system operation, making the module suitable for safety-critical applications requiring high availability and SIL 2 compliance.

Convenient Wiring and Maintenance
The design features dual removable barrier-type terminal blocks with shield terminal strips connected to chassis ground . Each block includes 24 terminals accommodating wire up to #12 AWG. The removable design facilitates maintenance without disturbing field wiring. LED status indicators enable rapid channel fault identification.

Seamless System Compatibility
The terminal board directly interfaces with Mark VI VCCC/VCRC controllers and PDIA I/O components . It maintains backward compatibility with older IS200TBCIH1B models and supports system upgrades. For Mark VIe systems, the C version is required for proper mechanical alignment with I/O pack mechanical supports .

Fail-Safe Diagnostic Architecture
The board incorporates multiple diagnostic features including excitation voltage monitoring that triggers a diagnostic warning if excitation falls below 40% of nominal voltage . All inputs can be forced to the open contact state for testing, and any input failing the diagnostic test enters a failsafe state generating a fault condition. In TMR systems, a fault is issued if board input does not match the voted value from all three boards.

Connector ID Validation
Each terminal board connector includes a unique identification device containing the board’s serial number, board type, revision number, and JR1/JS1/JT1 connector location information . The controller reads this chip during operation, triggering a hardware incompatibility fault if a mismatch is detected.

Cabling Configurations
The board provides multiple cabling options based on system redundancy requirements. JR1 is used for simplex systems, while all three connectors are utilized for TMR systems . Cables or I/O packs are plugged in depending on the Mark VI or Mark VIe system type and redundancy level.

Contact Input Circuit Design
Each input features two terminal points with positive DC source and input return path . The reference voltage establishes a transition threshold equal to 50% of the applied floating power supply voltage in isolation circuits. When voltage drops below this threshold, all contacts display open, with tracking clamped to no lower than 13 percent of the nominal rated supply voltage.

Application Scenarios

Gas Turbine Control Systems
The IS200TBCIH1C serves as a primary interface for gas turbine control applications within the GE Speedtronic Mark VI system . The terminal board collects essential turbine signals including overspeed protection, fire detection, emergency stop commands, and limit switch states. In combined-cycle power plants, the module monitors critical parameters such as compressor discharge pressure, exhaust temperature, and fuel valve positions. The 125 V DC excitation voltage ensures reliable operation even with long cable runs common in turbine installations.

Steam Turbine Management
For steam turbine applications, the terminal board acquires signals from valve position indicators, steam admission limit switches, extraction controls, and condenser monitoring systems . The board’s robust isolation protects the Mark VI controller from high-voltage transients generated by steam turbine auxiliary systems. In nuclear power plant auxiliary steam systems, the SIL 2 compliant design ensures safety-compliant bypass control and interlock execution.

Combined-Cycle Power Plants
In modern combined-cycle facilities, the IS200TBCIH1C manages complex bypass valve systems including high-pressure and low-pressure steam paths . The module’s 24 channels support dual HP and dual LP bypass configurations, monitoring valve position feedback, steam pressure switches, and temperature threshold contacts. During sudden load drop events, the board’s fast response enables rapid bypass valve actuation, diverting excess steam and preventing heat recovery steam generator overpressure.

Hydroelectric Power Stations
For pumped storage hydroelectric applications, the terminal board manages water-to-wire sequencing including reservoir gate positions, turbine inlet valve status, governor limit switches, and generator breaker states . The module’s enhanced processing capability handles complex water-pump and power-generation mode transitions with sub-millisecond response times. In a Southwest China pumped storage project, the IS200TBCIH1C demonstrated 8ms fault detection for critical valve positioning, preventing potential equipment damage during emergency mode switching.

Thermal Power Generation
In coal-fired power plants, the IS200TBCIH1C monitors boiler feed pump status, coal pulverizer limit switches, ash handling system positions, and flue gas damper states . The board’s diagnostic capabilities include analog input drift monitoring with threshold alert at ±0.5% over six months, digital output cycle counting predicting relay wear, and communication interruption logging. A German coal-fired plant using these diagnostic features extended bypass valve actuator lifespan by three years, reducing maintenance costs by $28,000 per turbine annually.

Industrial Automation Systems
Beyond power generation, the module finds application in requiring high-reliability digital input interfacing including chemical processing plants, oil and gas facilities, and heavy manufacturing environments . The industrial-grade design with extended temperature range and vibration resistance supports deployment in harsh conditions.

System Compatibility

• Control Platforms: GE Speedtronic Mark VI and Mark VIe

• Processors: VCCC and VCRC controller boards in VME racks

• I/O Components: PDIA I/O packets for Mark VIe systems

• Compatible Terminal Boards: IS200TBCIH1B (functionally equivalent), IS200TBCIH2C (32-channel version)

• Cabling: Molded connection cables for simplex and TMR configurations

• Certifications: CE, UL 61010-1, IEC 61326-1

• Safety Rating: IEC 61508 SIL 2 compliant