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6.2 Parameter description
6.2.3.7
"3.7 Statistics"
"3.7.1 Histograms"
Use of histograms
Histograms show the time distribution (relative resting duration) of a variable with respect to
20 part areas of the variable, in the form of a bar graph. Histogram statistics are available
for:
● 3.7.1.1 Position
● 3.7.1.2 Deviation
● 3.7.1.3 Temperature
If the positioner is in automatic mode, continuous statistics with regard to the duration for
which a fitting was operated in which section of the travel range are compiled. To this end,
the entire travel range of 0 to 100% is divided into 20 parts of equal size. The positioner
continuously registers the actual position and increments the operating hours counter on an
hourly basis, whereby the counter is assigned to a corresponding travel range. The
histogram statistics allow conclusions with regard to past operating conditions, and in
particular are used to assess the control property of the control circuit and entire fitting.
A histogram contains a class division over the entire measuring range of a variable, and
shows how much time the variable spent in each of the different classes. Using a position
histogram, you can assess, for example, whether a control valve was designed well, and
whether it was mainly used in the expected location.
Example:
T=1295H
y axis
x axis
120
Time in hours for which the histogram statistics were compiled.
The scaling of the y axis results from the maximum value determined.
In "3.7.1.1 Position" represents the range from 0 to 100%.
In "3.7.1.2 Deviation" represents the range from -10 to +10%.
In "3.7.1.3 Temperature" represents the range from -40 °C (-40 °F) to
+90 °C (194 °F).
SITRANS VP300 with or without HART
Operating Instructions, 03/2011, A5E01258666-03
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