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Set point deviation e histogram
7 Set point deviation e histo-
gram
The set point deviation histogram contains a
statistical analysis of any set point deviations
recorded. It provides information on to which
extent a set point deviation has occurred
during the valve service life and whether
faults may occur due to a restricted operat-
ing range or due to seat leakage.
Data are recorded automatically 15 minutes
after initialization (regardless of the operat-
ing mode selected). Data logging does not
need to be activated.
The positioner records the set point deviation
every second and assigns the data into pre-
dened classes. The distribution showing
how often the set point deviation remained
within a class is shown in a bar graph.
− 'Mean value': Average class assignment
of set point deviation throughout 'Moni-
toring duration'.
− 'Number of measurement points': Total
number of values recorded during the
'Monitoring duration'.
− 'Monitoring duration'
The measured data are saved every 24
hours in the positioner.
Short-term monitoring
In order to be able to recognize any short-
term changes in set point deviation, the posi-
tioner records the set point deviation accord-
ing to the adjusted 'Sampling time' and
analyses the last 100 measured values.
− 'Mean time': Contains the average class
assignment of set point deviations for the
last 100 measured values.
− 'Adjusted monitoring duration': 100 x
'Sampling time'
The positioner saves the set point deviations
in a circular buffer, which holds 100 mea-
sured values at one time.
Fig. 8: Diagnostics > Monitoring/tests > Histograms > Set point deviation e histogram
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