Samson 3767 - Adjusting the Proportional Band Xp and Air Delivery Q

EB8355-2EN 39
Operation
100%
0%
4
20 mA
12
4
20 mA
100%
0%
< >< <
< >< <
Referencevariable
Input signal
Deadband
OpenOpen
TravelTravel
ClosedClosed
Valve 2 Valve 1
Fig.13:Normal or split-range 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
permits.
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X
p
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X
p
valueistobeadjustedtobeas
smallaspossible,withoutconsiderable
overshooting occurring.
NOTICE
Always adjust the X
p
restriction be-
fore setting the starting point.
Changing it later will cause the zero
point to be shifted.