Yvib Functions; Vibration Monitoring Hardware - GE Mark VIeS System Manual

8.3 YVIB Functions

8.3.1 Vibration Monitoring Hardware

Internal to the YVIB I/O pack is application-specific hardware that provides signal conditioning to center and amplify signals
for improved analog-to-digital resolution. Each of the 13 differential amplifier inputs has a digital analog converter (DAC)
bias adjustment to null the dc content of the signal to better center the signal for the analog-to-digital (A/D) input range. The
DAC bias command is stored in the microprocessor to be used in the gap calculation for the Proximitor sensors.
Each input channel has a configurable gain that allows the vibration signal to be amplified. Refer to the configuration section
for a detailed listing of available gains based on channel number and I/O pack board revision. Analog processing provides
A/D conversion, digital-to-analog (D/A) conversion, and the digital pre-processing of sensor inputs. Sensor inputs are
digitally filtered, and then the sampled signals and the filtering information is passed on to microprocessor memory. Channels
1 through 8 and 13 use a multi-pole anti-aliasing filter with a band-pass frequency range of 7 kHz.
There is a tracking filter that is used to determine the vibration content of a turbine caused by a given rotation speed. This
same internal application hardware also runs the high-frequency section of the tracking filter and the 1x and 2x functions. The
1x vibration is the peak-to-peak magnitude of the radial movement in sync with the turbine shaft speed. The 1x calculation
also provides the phase relationship of the vibration phasor relative to the Keyphasor. The 2x calculation provides the radial
vibration component that is at twice the speed of the shaft.
The internal hardware of the YVIBS1A is different than YVIBS1B. The SIB provides an additional Keyphasor input (channel
12) and support for Combustion Dynamic Monitoring (CDM) sensors, as well as the ability to run in an Enhanced mode that
offers additional input resolution and other features.
234 GEH-6855_Vol_II GEH-6855_Vol_II Mark VIeS Functional Safety Systems Volume II
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