VAT 651 Series - Setpoint Ramp Adjustment

INSTALLATION Series
651
54/99 Edition 2014-07-10 605451EC
4.6.1.3 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
Choose the applicable formula depending on units you are familiar with.
t ramptime [
s
]
P
SFS
sensor full scale pressure
S
RAMP
setpoint ramp [s]
P
START
pressure start
P
END
pressure end
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.
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.
Local operation:
(‘Control View’, ‘Control Performance Analyzer’
or ‘Service Box 2‘)
Remote operation:
Go to ‘Setup / Control Parameter’ menu.
Select setpoint ramp.
It’s not possible to do ‘Setpoint ramp
adjustment‘ via remote operation.
ENDSTART
SFS
RAMP
PP
P
S
t
−
•=
P
START
P
SFS
t
P
END
Without setpoint ramp optimizing With setpoint ramp optimizing