Operation
82
SIP ART PS2 Manual
A5E00074631-01
Positioner 1 Positioner 2
100 %--SPRE 100 %--SPRA
SPRA SPRE
[0 % to 100 %]
y=x
100 %
0%
Positioner 1
Positioner 2
6.SDIR = FALL
6.SDIR = riSE
J
W
Setting range 1
Setting range 2
Total setting range
100 %
Figure 4-7 Example: Split range-operation with two positioners
Setpoint ramp UP
and
Setpoint ramp DOWN
The setpoint ramp is effective in automatic operation and limits the
speed of alteration of the active setpoint. When switching over from
manual operation to automatic the active setpoint is adjusted to the set-
point on the positioner with the setpoint ramp.
This bumpless manual/automatic switchover avoids excessive pressure
increases on long pipelines.
In the position TSUP = Auto the slower of the two travel times determi-
ned during initialization is used for the setpoint ramp. TSDO is then in-
effective.
Setpoint function (see figure 4-8, page 83)
Non--linear valve characteristics can be linearized with this function and
any flow characteristics simulated in linear valve characteristics.
Six valve characteristics are stored in the positioner
- equal percentage 1 : 25 (12.SFCT = 1 -- 25)
- equal percentage 1 : 33 (12.SFCT = 1 --33)
- equal percentage 1 : 50 (12.SFCT = 1 --50)
- inverse equal percentage 1 : 25 (12.SFCT = n1 -- 25)
10.TSUP
11.TSDO
12.SFCT
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