VAT 642 Series - Page 48

INSTALLATION Series
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48/119 Edition 2017-11-24 742280ED
4.7.1.3 Setpoint ramp adjustment
Setpoint ramp effects: Undershoot of pressure, Response time
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 = Setpoint Ramp
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.
P
START
P
SFS
t
P
END
Without setpoint ramp optimizing With setpoint ramp optimizing