VAT 642 Series Installation, Operating, & Maintenance Instructions page 52

4.7.1.3 Setpoint ramp adjustment
Setpoint ramp effects: Undershoot of pressure, Response time
Default value for Setpoint Ramp is 0. Adjustment range for Setpoint Ramp is from 0 to 10 s.
This parameter defines the time that is used to decrease / raise pressure between 2 setpoints. Especially
in pressure decrease situations at low flows pressure response can be improved much by adapting
setpoint ramp time.
Pressure chart
Without setpoint ramp optimizing
P
SFS
P
START
P
END
Choose the applicable formula depending on units you are familiar with.
S
=
RAMP
t
P
Adjustment procedure:
1. Start with optimal gain factor and sensor delay time according to preceding tuning steps.
2. Control a typical pressure / flow situation.
3. Control a lower pressure.
4. Repeat from step 2 with longer setpoint ramps until best response is achieved.
5. Verify pressure control response for a setpoint raise situation.
Local operation:
('Control View', 'Control Performance Analyzer'
or 'Service Box 2')
Go to 'Setup / Control Parameter' menu.
Select setpoint ramp.
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P P
−
START END
SFS
In case a long ramp time is required to get optimal performance for pressure
decrease situations it may be of advantage to apply different settings for decrease /
raise control situations.
Edition 2017-11-24
INSTALLATION
With setpoint ramp optimizing
t ramptime [s]
P sensor full scale pressure
SFS
S setpoint ramp [s]
RAMP
P pressure start
START
P pressure end
END
Remote operation:
It's not possible to do 'Setpoint ramp
adjustment' via remote operation.
Series 642
t
605403ED