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GE DS3800NVCD1B1B
Product Name: Ni120 RTD Input Board for GE Mark V Speedtronic Turbine Control System
Product Introduction: The DS3800NVCD1B1B is a dedicated Ni120 (nickel 120 Ω) RTD input board in GE’s Mark V Speedtronic turbine control family. The “1B1B” suffix indicates factory configuration for Ni120 sensors—the 120 Ω nickel RTDs common in older turbine installations—with 3-wire connection and the standard 37-pin termination. It reads bearing and winding temperature signals from legacy turbines that have not been converted to Pt100.
Detailed content
Technical Specifications:
- Number of inputs: 8, fully isolated
- RTD type: Ni120 (120 Ω at 0°C) only
- Connection: 3-wire (factory-configured, jumper-locked)
- Temperature range: -60 to +250°C
- Resolution: 16-bit (0.01°C)
- Accuracy: ±0.3°C at 25°C; ±0.5°C at 60°C
- Excitation current: 1 mA constant current
- Lead resistance compensation: Automatic, up to 50 Ω per lead
- Open RTD detection: Automatic, with alarm bit
- Short-circuit detection: Automatic, with alarm bit
- Isolation: 1500 V DC channel-to-backplane, 500 V DC channel-to-channel
- Termination: 37-pin D-sub connector
- Mounting: VMEbus 6U form factor
- Indicator LEDs: Green per-channel activity; red fault LED; green power LED
- Operating temperature: 0 to +60°C
Functional Features:
- 8 fully isolated Ni120 RTD input channels
- 16-bit resolution delivering 0.01°C temperature resolution
- Automatic lead resistance compensation (up to 50 Ω per lead)
- Built-in open RTD and short-circuit detection with alarm bits
- High isolation: 1500 V DC channel-to-backplane, 500 V DC channel-to-channel
- Factory-configured for 3-wire Ni120 sensors (jumper-locked, not user-changeable)
Material Composition: Industrial-grade 6U VME PCB with high-precision analog front-end components, 37-pin D-sub connector, isolated power and signal stages.
Structural Characteristics:
- 6U VMEbus form factor
- 37-pin D-sub termination connector
- Per-channel green activity LEDs, red fault LED, green power LED
- Factory-configured jumpers (locked for Ni120, 3-wire)
Working Principle: A 1 mA constant current excites each Ni120 RTD. The resulting voltage is conditioned, isolated, and converted by a 16-bit ADC. The 3-wire connection enables automatic lead resistance compensation (up to 50 Ω per lead). The digital values are passed over the VME bus to the Mark V controller. Open and short-circuit conditions are detected automatically and reported via alarm bits.
Installation Requirements: Install in a Mark V VMEbus 6U card slot. Terminate the 8 Ni120 RTD field cables on the 37-pin D-sub connector. Confirm the board’s factory configuration matches the installed sensor type (Ni120, 3-wire). Ensure VME backplane power is present.
Usage Precautions: This board is factory-configured exclusively for Ni120, 3-wire RTDs—it cannot be reconfigured for Pt100 or 2-wire/4-wire RTDs. Installing incorrect sensor types will yield erroneous readings or trigger fault alarms. Observe ESD handling. The board is for legacy Mark V turbines that have not been converted to Pt100. The 1 mA excitation and 16-bit ADC require periodic calibration verification to maintain the stated ±0.3°C accuracy.
