IS200VAICH1CCC - Analog Input/Output Board

SPECIFICATIONS:

Part Number: IS200VAICH1CCC
Manufacturer: General Electric
Series: Mark VI
Number of Channels: 24
Number of Inputs: 20 Analog Inputs
Input Span: 4-20 mA
Input Impedance: 4-20 mA
Input Types: Voltage, 4–20 mA
Input Converter Resolution: 16-bit A/D Converter
Product Type: Analog Input/Output (VAIC) Board
Scan Time: 10 ms
Output Converter: 12-bit
Temperature Operating: 0 to 60°C
Memory: 128 MB of flash memory
Ethernet: 10BaseT/100BaseTX (RJ-45)
Microprocessor: Intel Celeron 300 MHz
Size: 26.04 cm high x 1.99 cm wide
Repair: 3-7 Days
Availability: In Stock
Weight: 2 lbs
Country of Origin: United States
Manual: GEH-6421M

FUNCTIONAL DESCRIPTION:

IS200VAICH1CCC is an Analog Input/Output (VAIC) Board Manufactured and designed by General Electric as part of the Mark VI Series used in GE Speedtronic Gas Turbine Control Systems. The Analog Input/Output board accepts 20 analog inputs and controls 4 analog outputs. Each terminal board accepts 10 inputs and 2 outputs. Cables connect the terminal board to the VME rack, where the VAIC processor board is located. VAIC converts the inputs to digital values and transfers them over the VME backplane to the VCMI board, and then to the controller. For outputs, the VAIC converts digital values to analog currents and drives these through the terminal board into the customer circuit. VAIC supports both simplex and triple modular redundant (TMR) applications. When used in a TMR configuration, input signals on the terminal board are fanned out to three VME board racks, R, S, and T, each containing a VAIC. Output signals are driven with a proprietary circuit that creates the desired current using all three VAICs. In the event of a hardware failure, the bad VAIC is removed from the output, and the remaining two boards continue to produce the correct current. When used in a simplex configuration, the terminal board provides input signals to a single VAIC, which provides all of the current for outputs.

COMPATIBILITY:

There are two generations of the VAIC board with corresponding terminal boards. The original VAIC includes all versions before and including VAICH1C. VAICH1B is included in this generation. When driving 20 mA outputs, these boards support up to 500 load resistance at the end of 1000 ft of #18 wire. This generation of board requires a terminal board TBAIH1B or earlier for proper operation. They also work properly with all revisions of DTAI terminal boards. The newest VAICH1D and any subsequent releases are designed to support higher load resistance for 20 mA outputs. Drive voltage: up to 18 V is available at the terminal board screw terminals. This permits operation into loads of 800 with 1000 ft of #18 wire with a margin. This generation of the board requires TBAIH1C or later, or any revision of STAI.

OPERATION:

The VAIC board accepts 20 analog inputs, controls 4 analog outputs, and contains signal conditioning, an analog MUX, an A/D converter, and a D/A converter. The type of analog input, either voltage, 4-20 mA, or terminal board. Two of the four analog output circuits are 4-20 mA, and the other two can be configured for 4-20 mA or 0-200 mA. Inputs and outputs have noise suppression circuitry to protect against surges and high-frequency noise. In a TMR system, analog inputs fan out to the three control racks from JR1, JS1, and JT1. The 24 V dc power to the transducers comes from all three VME racks and is diode OR selected on the terminal board. Each analog current output is fed by currents from all three VAICs. The actual output current is measured with a series resistor, which feeds a voltage back to each VAIC. The resulting output is the voted middle value (median) of the three currents. The following figure shows VAIC in a TMR arrangement.

COMPRESSOR STALL DETECTION:

VAIC firmware includes gas turbine compressor stall detection, executed at 200 Hz. Two stall algorithms can be selected. Both use the first four analog inputs, scanned at 200 Hz. One algorithm is for small LM gas turbines and uses two pressure transducers (refer to the figure, Small (LM) Gas Turbine Compressor Stall Detection Algorithm). The other algorithm is for heavy-duty gas turbines and uses three pressure transducers (refer to the figure, Heavy Duty Gas Turbine Compressor Stall Detection Algorithm). Real-time inputs are separated from the configured parameters for clarity. The parameter CompStalType selects the type of algorithm required, either two transducers or three. PS3 is the compressor discharge pressure. A drop in this pressure (PS3 drop) indicates possible compressor stall. The algorithm also calculates the rate of change of discharge pressure, dPS3dt, and compares these values with configured stall parameters (KPS3 constants).

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FREQUENTLY ASKED QUESTIONS:

How many analog inputs and outputs does the VAIC board support?

The board supports 20 analog inputs and 4 analog outputs. Two outputs are fixed at 4-20 mA, and two are configurable for 4-20 mA or 0-200 mA. Inputs can be voltage or 4-20 mA signals via the terminal board.

What types of input signals are supported?

The board accepts analog voltage signals and 4-20 mA current signals. Signal conditioning circuits filter noise and stabilize inputs. Terminal boards provide proper routing and isolation for field connections.

What is the difference between simplex and TMR operation?

In simplex mode, a single VAIC board handles all inputs and outputs. In TMR mode, inputs are fanned out to three VAIC boards, and outputs are determined using median voting logic. This ensures correct operation even if one board fails.