EB 8389-1S EN
45
Set point deviation e histogram
Note:
Changing 'Sampling time' causes all
existing measured values to be delet-
ed from the circular buffer.
Defining parameters
1.
Set the 'Sampling time' for the short-term
monitoring.
2.
Select classification for status messages.
See
1.
Diagnostics > Monitoring/tests > Histograms
> Set point deviation e histogram > Short-
term monitoring
−
Sampling time: Adjustable as required,
[00:14:24 d.h:min:s]
2.
Device settings > Alarm settings > Status
classification > Valve
Seat leakage
−
May exist: [ ], , ,
Device settings > Alarm settings > Status
classification > Valve position
Manipulated variable range limitation
−
Lower: [ ], , ,
−
Upper: [ ], , ,
−
No change possible: [
], , ,
Positioner-valve linkage
−
Travel transmission not optimal:
[ ], , ,
7.1
Analysis and monitoring
Ideally, the set point deviation should be
nearly 0 %.
Set point deviations greater than 1 % follow
-
ing in quick succession pinpoint to a limita-
tion of the upper operating range. In this
case, the positioner generates the 'Manipu
-
lated variable range limitation' and 'Posi
-
tioner-valve linkage' messages with the se
-
lected status classifications.
Set point deviations smaller than 1 % follow
-
ing in quick succession pinpoint to a limita-
tion of the lower operating range or to seat
leakage. The positioner generates the 'Ma
-
nipulated variable range limitation', 'Posi
-
tioner-valve linkage' and 'Seat leakage'
messages with the selected status classifica
-
tions.
If almost all set point deviations during the
short-term monitoring are greater than 1 %
or smaller than –1 %, this may indicated that
the actuator or valve stem is jammed. The
positioner generates the 'Manipulated vari
-
able range limitation' and 'Positioner-valve
linkage' messages with the selected status
classifications.
Diagnostics > Monitoring > Valve
−
Seat leakage: , , ,
Diagnostics > Monitoring > Valve position
−
Manipulated variable range limitation: ,
, ,
−
Positioner-valve linkage: , , ,
