IS215VAMBH1A

The IS215VAMBH1A is an acoustic monitoring card assembly module developed by GE under Mark VI series. It has two TAMB boards that provide eighteen channels of signal conditioning and eighteen channels of acoustic monitoring. This board, along with one or two TAMB terminal boards, supports acoustic monitoring for frame 6, 7, or 9 gas turbines.

• Because of its high impedance DC bias, the board detects open connections between a TAMB board and a charge amplifier. The dc bias control allows for RETx, SIGx, and return line options, as well as 28 V bias or ground applied to the signal line. Each channel outputs a buffered BNC signal that is the input signal minus the dc bias.
• The module consists of a front faceplate, two d-type cable connectors, and three LED board status indicators.
• Two backplane connectors are situated side by side on the board's rear. Vertical pin connectors are also included on the board. There are numerous integrated circuits on the board. Xilinx field-programmable gate arrays are among them. Two inductor coils are situated between the backplane and the connections.
• On the board, there are nine 3-pin jumpers. One side is connected to the return signal (RETx), while the middle pin is connected to PCOM.

IS215VAMBH1A Installation

Current-limited +24 V dc and +24 V dc power supply outputs are provided by each channel. For the PCB sensors, a constant current source is attached to the SIGx line. When the signal is a logic-level low through an output on the VAMB, the input signal, CCSELx, is False. The continuous current output must be deselected until the configuration parameters are loaded, therefore the output must be False (logic-level low) upon power-up.

IS215VAMBH1A Operation

The VAMB program has the following features:

• 18 channels of acoustic monitoring
• Mark VI toolbox for changing configuration constants
• 40 ms frame rate updates for signal space variables utilized by the application software
• Offline and online diagnostics to examine the hardware

A/D Compensation

Any gain or offset mistake caused by initial component variations is eliminated by using the A/D compensation function. For the A/Ds it controls, the firmware has an auto-calibration capability. Each of the 18 analog channels is compared to a gold standard A/D channel in the auto-calibration feature. A standard high-precision voltage reference and the A/D common are used to calibrate the gold standard A/D channel.

A/D Gain Adjust

The channel gain in the hardware is controlled by the configuration parameter Gain defined for each channel. This enables the amplification of low-level signals in the analog to digital conversion gear to improve resolution. There are four gain options: 1, 2, 4, and 8. The gain setup is written to the FPGA VSPA input amplifier 4x and 2x gain control registers via the channel control. Because the signal is divided by the gain factor in the firmware to result in a net gain of 1 for the signal regardless of the gain factor used, the signal level estimated by the VAMB firmware will not change with a change in the Gain parameter.

Diagnostics

• The state of the VAMB front panel is indicated by three LEDs at the top.
• The RUN state is flashing green, whereas the FAIL condition is a solid red.
• The third LED is generally off, but if the board has a diagnostic alarm, it will display a continuous orange.
• Each input has two customizable degrees of system limit checking. These limits can be set to enable/disable,> = or =, latching/non-latching, and latching/non-latching.
• The out-of-limits are reset with RESET SYS. If this limit is exceeded, a signal is generated by the system limit logic.