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Installation, Operating & Maintenance Instructions
Series 615 DN 40 (I.D. 1.5”), RS485
VAT Vakuumventile AG, CH-9469 Haag, Switzerland
Tel +41 81 771 61 61 Fax +41 81 771 48 30 [email protected] www.vatvalve.com
289111EB
2013-02-05
34/96
3.6.6.2
Fixed PI
This valve may be used for downstream or upstream pressure control depending on configuration. The PI parameters of
the pressure controller require correct adjustment. These parameters must be set once during system setup and are
stored in the device memory which is power fail save. Based on the PI controller configuration, the valve is able to run fast
and accurate pressure control cycles. The PI parameters can be calculated approximately with the formulas below. On
request VAT can provide a parameter calculation tool .
Note:
In
downstream
control mode valve will move towards open when current pressure is higher then setpoint.
In
upstream
control mode valve will move towards close when current pressure is higher then setpoint.
P-Gain
Step 1 (choose the applicable formula depending on units you are familiar with):
d V p
SFS
K =
q
max
1.737 10
6
d
Valve
diameter [
mm
]
V
Chamber
volume [
l
]
p
SFS
Sensor
full scale
1)
[
Pa
]
q
max
max.
gasflow
to control [
Pa m
3
/s
]
d V p
SFS
K =
q
max
1.737 10
3
d
Valve
diameter [
mm
]
V
Chamber
volume [
l
]
p
SFS
Sensor
full scale
1)
[
mbar
]
q
max
max.
gasflow
to control [
mbar l/s
]
d V p
SFS
1.151
K =
q
max
d
Valve
diameter [
inch
]
V
Chamber
volume [
l
]
p
SFS
Sensor
full scale
1)
[
Torr
]
q
max
max.
gasflow
to control [
sccm
]
1)
In case of 2 sensor operation use high range sensor for calculation (615 . . - . . .
Q
- . . . . version only)
Step 2:
P-Gain = K (but max. 10)
K
Gain
I-Gain
Step 1 (choose the applicable formula depending on units you are familiar with):
66
V
T
N1
=
d
d
Valve
diameter [
mm
]
V
Chamber
volume [
l
]
2.6
V
T
N1
=
d
d
Valve
diameter [
inch
]
V
Chamber
volume [
l
]
Step 2:
T
N2
= T
N1
(but max. 3)
T
N1
Reset time
Step 3:
K
I-Gain =
T
N2
K
Gain
T
N2
limited reset time