EB 8387-5 EN
85
Appendix
Code
no.
Parameter
– Readings/
values [default setting]
Description
15* Set point cutoff increase
50.0 to 100.0 %, ESC
If the set point w reaches up to the entered percentage at the final
value that causes the valve to open, the actuator is immediately
filled with air (with AIR TO OPEN) or completely vented (with AIR
TO CLOSE). This action always lead to the valve being completely
opened. The signal pressure can be limited in Code 16.
Codes 14/15 have priority over Codes 8/9/10/11.
Codes 21/22 have priority over Codes 14/15.
Example:
Set the cutoff to 99 % for three-way valves.
16* Pressure limit
[OFF], P 1,4/2,4/3,7, ESC
The signal pressure to the actuator can be limited in stages.
After changing a pressure limit already set, the actuator must be
vented once (e.g. by selecting the fail-safe position (SAFE) over
Code 0).
Note:
Do not activate pressure limitation for double-acting actua-
tors (with fail-safe position AIR TO OPEN).
17* Proportional-action coeffi
-
cient Kp level
0 to 17 [7], ESC
Changing the K
P
and T
V
levels:
During positioner initialization, the values for K
P
and T
V
are opti-
mized. If the positioner tends to overshoot impermissibly due to
other disturbances, the K
P
and T
V
levels can be adapted accord-
ingly after initialization. Increment T
V
level until desired behavior
is reached or when the maximum value of 4 is reached, the K
P
level can be decreased in increments.
K
P
level changes affect the set point deviation.
18* Derivative-action time Tv
level
1, [2], 3, 4, OFF, ESC
See Code 17
A change of the T
V
level has no effect on the system deviation.
19* Tolerance band
0.1 to 10.0 %, [5.0 %] of the
operating range, ESC
Used for error monitoring.
Determination of the tolerance band in relation to the operating
range. Associated lag time (30 s) is a reset criterion.
If a transit time is determined during initialization which is six
times longer than 30 s, the six-fold transit time is accepted as the
lag time.
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