The GE IS200VAICH1DAA Analog Input/Output Board is a high-performance analog I/O processor board used within GE Industrial Control Systems. As a member of the VAIC board family, the IS200VAICH1DAA Analog Input/Output Board accepts 20 analog inputs and controls 4 analog outputs, providing the signal conditioning, analog multiplexing, analog-to-digital conversion, and digital-to-analog conversion required for analog process signal acquisition and control in Mark VI control architectures. Each terminal board accepts 10 inputs and 2 outputs, and cables connect the terminal board to the VME rack where the VAIC processor board is located. The VAIC converts the inputs to digital values and transfers them over the VME backplane to the VCMI board and then to the controller, while for outputs the VAIC converts digital values to analog currents and drives these through the terminal board into the customer circuit.
The IS200VAICH1DAA Analog Input/Output Board is identified by the GE part numbering convention used throughout the Industrial Control Systems product line. The "IS200" prefix identifies the board as a GE Industrial Control Systems product, with "200" specifically indicating that the board is a base-level assembly. The "VAIC" acronym identifies the board's functional designation as an Analog Input/Output Board. The "H1" designation identifies the hardware group, while the "DAA" suffix identifies the artwork and functional revision combination. All digits are important when ordering or replacing any board, as boards of different revision levels may not contain identical hardware, and GE ensures backward compatibility of replacement boards while noting that different revision levels may not contain identical components.
The IS200VAICH1DAA Analog Input/Output Board is the VAICH1D version of the VAIC family, which is the newest generation designed to support higher load resistance for 20 mA outputs. This generation provides up to 18 V available at the terminal board screw terminals, permitting operation into loads of 800 ohms with 1000 feet of #18 wire with margin, compared to the earlier VAICH1C and prior versions which supported up to 500 ohms load resistance. The VAICH1D board requires the TBAIH1C or later terminal board, or any revision of the STAI terminal board, for proper operation, while it also works properly with all revisions of the DTAI terminal boards.
This product introduction provides detailed technical information, functional descriptions, connector assignments, configuration guidance, and comprehensive specifications for the GE IS200VAICH1DAA Analog Input/Output Board, serving as an essential reference for control system engineers, maintenance technicians, and system integrators working with GE industrial control equipment.
Functional Architecture and Signal Processing
The IS200VAICH1DAA Analog Input/Output Board is built around a flexible and high-performance analog signal processing architecture that supports up to 20 analog inputs and 4 analog outputs, with the input type, whether voltage, 4–20 mA, or ±1 mA, selected by jumpers on the 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 surge and high-frequency noise.
The board contains signal conditioning, an analog multiplexer, an A/D converter, and a D/A converter, providing a complete analog signal chain from the field wiring to the digital control system. The A/D converter is a 16-bit converter with 14-bit resolution, and the normal scan time is 10 ms (100 Hz), with inputs 1 through 4 available for scan at 200 Hz. The measurement accuracy is better than 0.1% of full scale, and the D/A converter is a 12-bit converter with 0.5% accuracy.
The input impedance of the IS200VAICH1DAA Analog Input/Output Board is 250 ohms at 4–20 mA, 5,000 ohms at ±1 mA, and 500,000 ohms at voltage input, allowing the board to interface with a wide range of transmitters and voltage sources. The input noise suppression includes a hardware filter on the first 10 circuits (J3) with a single pole down break at 500 rad/sec, a hardware filter on the second 10 circuits (J4) with a two pole down break at 72 and 500 rad/sec, and a software filter using a two pole low pass filter configurable for 0, 0.75, 1.5 Hz, 3 Hz, 6 Hz, or 12 Hz. The AC common mode rejection is 60 dB at 60 Hz with up to ±5 V common mode voltage, and the DC common mode rejection is 80 dB with −5 to +7 V peak common mode voltage. The common mode voltage range is ±5 V, with ±2 V CMR for the ±10 V inputs.
Simplex and TMR Applications
The IS200VAICH1DAA Analog Input/Output Board supports both simplex and triple modular redundant (TMR) applications, providing the flexibility required for different system architectures.
In a simplex configuration, the terminal board provides input signals to a single VAIC, which provides all of the current for outputs. The board accepts 20 analog inputs and controls 4 analog outputs, with two TBAI terminal boards providing the field-side termination. The analog I/O capacity using two TBAI terminal boards includes 16 inputs of ±10 V DC, ±5 V DC, or 4–20 mA, 4 inputs of 4–20 mA or ±1 mA, 2 outputs of 0–20 mA or 0–200 mA, and 2 outputs of 0–20 mA.
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. 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, and 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, or median, of the three currents, providing the fault tolerance and high availability required for critical control applications.
Compressor Stall Detection
The IS200VAICH1DAA Analog Input/Output Board firmware includes gas turbine compressor stall detection, executed at 200 Hz. Two stall algorithms can be selected, and both use the first four analog inputs, scanned at 200 Hz. One algorithm is for small LM gas turbines and uses two pressure transducers, while the other algorithm is for heavy-duty gas turbines and uses three pressure transducers.
The compressor stall detection algorithm uses the compressor discharge pressure PS3 as the primary input, and a drop in this pressure indicates a possible compressor stall. The algorithm also calculates the rate of change of discharge pressure, dPS3/dt, and compares these values with the configured stall parameters, the KPS3 constants. The compressor stall trip is initiated by VAIC, which sends the signal to the controller where it is used to initiate a shutdown, and the shutdown signal can be used to set all the fuel shut-off valves through any relay output. The compressor stall detection and relay operation occur within 30 ms, providing a fast and reliable response to a stall condition.
Installation and Wiring
The IS200VAICH1DAA Analog Input/Output Board is designed for straightforward installation in the VME processor rack. To install the board, power down the VME processor rack, slide in the board, and push the top and bottom levers in with your hands to seat its edge connectors, then tighten the captive screws at the top and bottom of the front panel. Cable connections to the terminal boards are made at the J3 and J4 connectors on the lower portion of the VME rack, which are latching type connectors to secure the cables. After powering up the VME rack, check the diagnostic lights at the top of the front panel.
The board size is 26.04 cm high by 1.99 cm wide by 18.73 cm deep (10.26 in x 0.782 in x 7.375 in), and the power consumption is less than 31 W. The operating temperature range is 0 to 60 °C (32 to 140 °F), making the board suitable for installation in standard industrial control cabinets.
Diagnostics and Fault Detection
The IS200VAICH1DAA Analog Input/Output Board provides comprehensive diagnostic capabilities that assist with system verification and fault isolation. Three LEDs at the top of the VAIC front panel provide status information, with the normal RUN condition being a flashing green, FAIL being a solid red, and STATUS being normally off but displaying a steady orange if a diagnostic alarm condition exists in the board.
Each analog input has hardware limit checking based on preset, non-configurable high and low levels set near the ends of the operating range, and if this limit is exceeded a logic signal is set and the input is no longer scanned. If any one of the input's hardware limits is set, it creates a composite diagnostic alarm, L3DIAG_VAIC, which refers to the entire board. Each input also has system limit checking based on configurable high and low levels, which can be used to generate alarms and can be configured for enable or disable and as latching or non-latching.
In TMR systems, if one signal varies from the voted value by more than a predetermined limit, that signal is identified and a fault is created, providing early indication of a problem developing in one channel. The board monitors the D/A outputs, output currents, total current, suicide relays, and 20/200 mA scaling relays, checking these for reasonability and creating a fault when a problem is detected. The TBAI terminal board has its own ID device that is interrogated by the VAIC, and if a mismatch is encountered, a hardware incompatibility fault is created.
Diagnostics monitor each output, and a suicide relay disconnects the corresponding output if a fault cannot be cleared by a command from the processor, providing an additional layer of protection for the field devices and the process.
Application Suitability and System Integration
The IS200VAICH1DAA Analog Input/Output Board is a versatile analog interface that can be used in a wide variety of GE Industrial Control System applications. Its 20 analog inputs, supporting 4–20 mA, ±1 mA, ±5 V DC, and ±10 V DC signals, and its 4 analog outputs, supporting 4–20 mA and 0–200 mA, allow the board to interface with pressure transmitters, temperature transmitters, flow meters, level sensors, valve positioners, actuators, and many other analog field instruments.
The board's support for both simplex and TMR applications makes it suitable for a wide range of system architectures, from cost-sensitive simplex installations to critical TMR installations where high availability is required. In TMR applications, the board's fanned inputs, diode-OR selected transmitter power, and median-voted outputs provide the fault tolerance and reliability required for the most demanding control applications.
The board's built-in compressor stall detection, with the two-transducer and three-transducer algorithms and the 200 Hz scan rate, provides a fast and reliable means of detecting compressor stall in gas turbine applications, and the shutdown signal can be used to set all the fuel shut-off valves through any relay output, providing a comprehensive protection function.
The board's higher load resistance capability, with up to 800 ohms supported with 1000 feet of #18 wire, allows the board to drive longer cable runs and higher impedance loads than the earlier VAIC generations, providing greater flexibility in the field wiring and the connected field devices.
Maintenance and Lifecycle
The IS200VAICH1DAA Analog Input/Output Board is designed for long service life with minimal maintenance. The board contains no moving parts, and its robust construction ensures high reliability in continuous industrial operation. Routine maintenance consists of periodic visual inspection of the board, connectors, and LEDs, verification that the analog input and output signals are within specification, and confirmation that the diagnostic LEDs indicate normal operation.
The board's diagnostic features, including the hardware and system limit checks, the TMR voting, the output monitoring, and the onboard ID chip, simplify troubleshooting and ensure that the correct board is installed in each location. If a diagnostic alarm condition exists, the STATUS LED displays a steady orange, alerting the maintenance technician to a problem with the board or the field wiring.
If the board requires replacement, the process is straightforward. After powering down the VME processor rack and verifying that no power exists, the cables should be disconnected from the J3 and J4 connectors, the captive screws loosened, and the board removed from the rack using the top and bottom levers. The replacement board should be installed in the same position, the cables reconnected as labeled, and the diagnostic LEDs checked before returning the system to service.
GE Industrial Control Systems ensures compatibility of its replacement boards, even though boards of different revision levels may not contain identical hardware. When ordering a replacement IS200VAICH1DAA Analog Input/Output Board, provide the complete part number and description, the drive or system serial number, and the Material List (ML) number. The factory may substitute later versions based on availability and design enhancements, but backward compatibility of replacement boards is guaranteed.
Conclusion
The GE IS200VAICH1DAA Analog Input/Output Board is a reliable, robust, and versatile analog interface for GE Industrial Control Systems. Its 20 analog inputs, supporting multiple signal types and ranges, its 4 analog outputs with 4–20 mA and 0–200 mA capability, its higher load resistance capability with up to 800 ohms supported, its built-in compressor stall detection, and its support for both simplex and TMR applications provide the flexibility, accuracy, and reliability required for a wide range of industrial analog measurement and control applications.
With its VME rack mounting, clearly labeled connectors, comprehensive diagnostics, and compatibility with the Mark VI control system and the TBAI, STAI, and DTAI terminal boards, the IS200VAICH1DAA Analog Input/Output Board is designed for easy installation, verification, and maintenance. Backed by GE's quality manufacturing, global support network, and commitment to backward compatibility, the IS200VAICH1DAA Analog Input/Output Board continues to deliver the performance, durability, and reliability that industrial users expect from GE. Whether used in a new installation or as a replacement for an existing board, the IS200VAICH1DAA Analog Input/Output Board provides the analog input and output functionality required for reliable and efficient control system operation.
