Samson 3766 - Adjusting the Proportional Band Xp and Air Delivery Q; Settings for Actuator with Actuator Stem Extends Fail-Safe Action

EB 8355-1 EN 39
Operation
5.1.1 Adjusting the proportional
band Xp and air delivery
Q
1. Close the volume restriction (11) as far
as the required positioning speed per-
mits.
Check the positioning speed by pushing
the diaphragm lever (3) as far it will go.
2. Adjust the reference variable at the input
toapprox.50%ofitsrange.
3. Turnthezeroadjuster(6.2)untilthe
valve has reached approx. mid-travel.
4. Use the adjuster (8) to set the proportion-
albandXptoavaluehalfway(half
turn).
5. Check the valve's tendency to hunt and
thepositioningspeedbybrieytapping
the diaphragm lever (3).
TheXpvalueistobeadjustedtobeas
small as possible, without considerable
overshooting occurring.
Always adjust the Xp restriction before set-
ting the starting point.
Changing it later will cause the zero point to
be shifted!
5.1.2 Settings for actuator with
“actuator stem extends”
fail-safe action
To allow the valve to close with full force, the
diaphragm chamber must be fully vented
when the reference variable reaches its lower
value (operating direction <<) or upper
value (operating direction <>).
As a result, adjust the input signal to a slight-
ly increased starting point of 0.23bar for di-
rect operating direction <<; for reverse oper-
ating direction <>, adjust the input signal to
a slightly reduced starting point of 0.97bar.
Starting point (e.g. 0.23bar)
1. Adjusttheinputsignalto0.2baratthe
pressure adjuster.
2. Turnthezeroadjuster(6.2)untilthe
valve just starts to move from its initial
position.
3. Reducetheinputsignalto0barand
slowly increase it again. Check whether
the valve starts to move at exactly
0.23bar.
Correct any deviation at the zero adjust-
er(6.2).
Upper range value (span) e.g. 1bar
1. Once the starting point has been set, in-
creasetheinputsignalto1baratthe
pressure adjuster.
Atexactly1bar,theplugstemmuststand
still,havingmovedthrough100%travel
(watch the travel indicator at the valve).
NOTICE
!
NOTICE
!