IS200VAICH1B

IS200VAICH1B is an Analog Input Terminal Board manufactured and designed by General Electric as part of the Mark VI Series used in gas turbine control systems. The Analog Input Board (VAIC) manages four analog outputs and accepts 20 analog inputs. There are ten inputs and two outputs on each Analog Input terminal board. The terminal board is connected via cables to the VME rack housing the VAIC processor board. The inputs are converted to digital values by the VAIC, which then sends them through the VME backplane to the VCMI board before passing them on to the controller. For the VAIC to monitor 20 inputs, two terminal boards are needed.

IS200VAICH1B Functional Description

• The VAIC generates outputs by converting digital values to analog currents for delivery to the customer circuit via the terminal board.
• Applications for triple modular redundant (TMR) and simplex are both supported by the VAIC. The terminal board's input signals are spread out to three VME board racks, R, S, and T, each of which has a VAIC when utilized in a TMR arrangement.
• A unique circuit that uses all three VAICs to generate the desired current drives the output signals. The remaining two boards continue to produce the proper current in the event of a hardware failure while the defective VAIC is taken out of the output. The terminal board feeds input signals to a single VAIC when employed in a simplex configuration.
• The entire output current is then provided by the single VAIC.

Installation

• Turn off the processor rack for the VME.
• Insert the VAIC board, then, using your hands, press the top and bottom levers into the seat of the edge connectors.
• Tighten the captive screws on the front panel's top and bottom.

Operation

• The VAIC board features signal conditioning, an analog MUX, an A/D converter, and a D/A converter in addition to 20 analog inputs, four analog outputs, and signal control. On the terminal board, a jumper is used to specify the kind of analog input: voltage, 4-20 mA, or 1 mA.
• Four analog output circuits—two of which are 4-20 mA—can be set up using terminal board jumpers for 4-20 mA or 0-200 mA on the other two. To guard against surge and high-frequency noise, inputs and outputs incorporate noise suppression circuitry.

IS200VAICH1B Diagnostics

• Each analog input features hardware limit checking based on predetermined (non-configurable) high and low levels that are placed close to the operational range's edges. In case of exceeding this limit, a logic signal is set and the input is no longer examined. L3DIAG VAIC, a composite diagnostic alert that pertains to the entire board, is generated if any input hardware limits are set. From the toolbox, you may get more information about each diagnosis. With the use of the RESET DIA signal, the diagnostic signals can each be independently latched and subsequently reset.
• System limit verification for each input is done using customizable high and low levels. These restrictions, which can be adjusted for enable/disablement and latching/non-latching, can be utilized to trigger alarms. The out-of-bounds are reset via RESET SYS.
• In TMR systems, one signal is recognized and a defect is issued if it deviates from the median value—the value that was voted on—by more than a predefined amount. This may give a head start on the development of an issue in one channel.
• The VAIC board queries an ID device that is unique to the TBAI terminal board. The terminal board serial number, board type, revision number, and the placement of the JR, JS, and JT connectors are all encoded into a read-only chip along with the board ID. A hardware incompatibility fault is produced when the chip is read by the I/O processor and a mismatch is discovered.