BRUEL & KJAER VIBROCONTROL 8000 - 13.4.1 Low Trigger (RPM), High Trigger (RPM) - Static Data Collection; 13.4.1.1 Exception Deviation (PI, XC, SD, and HD)

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13.4.1 Low Trigger (RPM), High Trigger (RPM) – Static Data Collection
The Low to High Trigger setting defines the machine transient window. This window is used to control
Exception Deviation, PI Compression, and Boost Mode.
Feature
Description
Reduced Exception Deviation
(divide by 4)
Defines when higher density static data is saved (by the Adapter) during
start-ups and shutdowns.
This feature is always enabled.
PI Compression Off/On
(PI systems only)
Defines when PI compression will be disabled, and more data will be
stored.
This feature is always enabled.
Boost mode (rarely used)
See 13.3.5
Table 13-8) Machine transient window
NOTE!
Most of the time the machine transient window is only used to control higher resolution static
data collection. If Boost Mode is being used, the same window is used for both features.
When the machine speed is within the defined window the SETPOINT PI/XC Adapter will collect
higher resolution static data by modifying two data collection settings:
• Reduces the Exception Deviation (divide by 4)
• Turns data compression off (PI Systems only)
There is no enable/disable for this feature. It is always on.
13.4.1.1 Exception Deviation (PI, XC, SD, and HD)
Many of the 80 ms data samples coming from the UMM will be redundant (i.e. 25.0 µm, 25.1 µm, 25.0
µm, 25.1 µm etc.). Redundant data is filtered using the Exception Deviation setting.
Exception Deviation defines when a new sample should be stored. For example:
• There was a significant change in the data (i.e. 25.0 µm to 35.0 µm).
• There have been no significant changes in the data, but a long time has passed since that last
data point was stored (10 seconds).
Filtering the data using Exception Deviation improves system performance; less data is stored, and
data retrieval is much faster. The SETPOINT PI Adapter manages the Exception Deviation values.
Examples of Exception Deviation are shown below.
Channel Type
Sensor
Exception Deviation
Radial Vibration (mils (µm) pp))
200 mV/mil (7.87 mV/ µm)
0.06 mils (1.52 µm)
Acceleration (g)
100 mV/g
0.012 g
Table 13-9) Exception Deviation examples
For CMS-XC, SD, and HD the Exception Deviation setting is not shown and cannot be edited. For
CMS-PI the setting is an attribute of the PI tag and can be edited using PI tools.
When the machine is in a transient condition, the SETPOINT PI Adapter will reduce the Exception
Deviation setting (divide by 4). This allows higher resolution data to be stored and improves diagrams
(Bode, Polar, etc.) used for startup and shutdown analysis (see 13.4.1).