26
Commissioning
- continued -
Setting the control parameters
Press button
to open the parameter setting window for the controller.
For each parameter setting press the green
button. Use the on-screen numberpad to enter
the desired value.
Screen display 4
Press button
to scroll back or
press button
to go to the parameter
setting window of the 3-element control.
C
Bar chart indication of setpoint [in %]
D
Bar chart indication of manipulated variable Y [in %], relative to valve lift
E
Neutral zone (dead band)
Key
Parameter
Deviation
Control valve
Proportional
band
Pb
larger
large remaining deviation
responds slowly
smaller
small remaining deviation
responds quickly and may open/closes
all the time
Example
Measuring range 100% = 200 mm of sightglass
Setpoint SP = 80 % of measuring range = 160 mm
Proportional band Pb = +/- 20% of setpoint = +/- 16% = +/- 32 mm
If the measuring range is 100% (200 mm) and the setpoint 80% (160 mm),
the proportional band will be +/- 16% (+/- 32 mm) or within the range of
128 to 192 mm.
Integral action
time
ti
larger
slow correction of deviations
responds slowly
smaller
fast correction of deviations, control
system may tend to overshoot
responds quickly
Neutral band
E
larger
time-delayed correction of deviations
will not respond until the deviation ex-
ceeds the neutral band
smaller
fast correction of deviations
Valve travel
time
tt
(only NRR
2-52)
Adjust the valve travel time specified by
the valve manufacturer.
Additional information on control parameter settings
C
D
NRR 2-5.
E
Summary of Contents for NRR 2-52
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