Samson 430 Series, Mounting And Operating Instructions

Page: 20 / 78

20 EB 7030 EN
Design and principle of operation
The pressures acting in the diaphragm cham -
bers R1 and R2 equal each other.
The position of the force switch changes until
the controller output pressure assumes a val
-
ue assigned to the controlled variable x and
the adjusted proportional-action coefficient
Kp, i.e. until the system deviation is eliminat
-
ed.
The proportional-action coefficient Kp is ad
-
justed at the restrictor (9), while the reset
time Tn is adjusted at the restrictor (10). The
zero adjuster (8) is used to calibrate the con
-
troller module.
The turnboard A determines the direction of
action of the controller. The direction of ac -
tion is changed by turning the turnboard.
See section 3.1.1.
5.3.2 Type 3434 Controller
Module
The controller modules feature a box-shaped
comparator that operates according to the
force-balance method. The proportional-ac
-
tion coefficient Kp can be adjusted at a re -
strictor within the range between 1 and 25.
Type 3434-2 PI Controller Module (Fig. 8)
The controlled variable x and the set point w
are transferred as gauge pressures between
0.2 and 1 bar or 3 to 15 psi via
turnboard
A to the diaphragm chambers (R1 and R2).
When x exceeds w, the force switch (23) is
lowered and opens the plug.
The supply air flows into diaphragm cham
-
ber R2 and the output pressure y
A
increases.
The output pressure is routed over the Tn
restrictor (10) into the volume of the 1:1
booster (24), whose output pressure is fed
back into the diaphragm chamber R1.
R
24
w
Z
y
A
K
p
T
n
S
A
x
9 8
R1
10
21
R2
23
Fig. 8: Type 3434-2 Controller Module
8 Zero adjuster
9 Kp adjuster
10 Tn adjuster
21 Diaphragm
23 Force switch
24 Booster
R1 Diaphragm chamber R1
R2 Diaphragm chamber R2
A
Direction of action of
turnboard