IS200VAICH1ACA - Analog Input/Output (VAIC) Board

SPECIFICATIONS:

Part Number: IS200VAICH1ACA
Manufacturer: General Electric
Series: Mark VI
Number of Channels: 24
Input Span: 4�20 mA
Input Impedance: 250 Ohms
Scan Time: 10 ms
Power Consumption: 31 mW
Size: 16.2 cm high x 8.6 cm
Repair: 3�7 Days
Availability: In Stock
Country of Origin: United States
Manual: GEH-6421M

FUNCTIONAL DESCRIPTION:

IS200VAICH1ACA is an Analog Input/Output (VAIC) Board manufactured and designed by General Electric as part of the Mark VI Series used in GE Speedtronic Control Systems. The Analog Input/Output (VAIC) 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:

The Analog Input/Output (VAIC) 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.

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. Transmitters/transducers can be powered by the 24 V dc source in the control system, or can be powered independently. Diagnostics monitor each output, and a suicide relay disconnects the corresponding output if a fault cannot be cleared by a command from the processor. Hardware filters on the terminal board suppress high-frequency noise. Additional software filters on VAIC provide configurable low-pass filtering.

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).

WOC is proud to offer the largest stock of OEM Replacement parts for GE Speedtronic Gas Turbine Control Systems, ensuring you have access to the critical components you need for maintenance, upgrades, or replacements. In addition to supplying genuine parts, we specialize in repairing faulty boards and providing unused and professionally rebuilt boards, all supported by a reliable warranty to guarantee performance and peace of mind. Our team of experts is available round the clock to offer technical guidance and solutions tailored to your automation and control system requirements. Committed to maximizing uptime and operational efficiency, we are always ready to assist with any OEM needs, from parts procurement to repairs. For pricing, availability, or support, don't hesitate to get in touch with our team via phone or email at WOC. Your automation challenges are our top priority, and we are dedicated to delivering fast, reliable, and expert solutions.

FREQUENTLY ASKED QUESTIONS:

What is the IS200VAICH1ACA?

The IS200VAICH1ACA is an Analog Input/Output (VAIC) Board used in GE Mark VI Speedtronic turbine control systems. It handles 20 analog inputs and 4 analog outputs for critical turbine monitoring and control. The board converts analog signals to a digital format for the controller and generates precise analog output currents for field devices.

What is the input impedance of the VAIC board?

The IS200VAICH1ACA has an input impedance of 250 Ohms, designed to accurately convert 4-20 mA signals from field transmitters to digital values. This impedance ensures minimal signal distortion while maintaining compatibility with standard process control instrumentation.

How does the VAIC board handle analog-to-digital conversion?

The board integrates an analog multiplexer (MUX) and high-precision A/D converters. Inputs are conditioned and multiplexed before conversion to digital format, ensuring reliable data transfer over the VME backplane to the VCMI and controller. Sampling occurs every 10 ms for real-time processing.