Samson Series 420 User manual

Mounting and
Operating Instructions
EB 7500 EN
Edition July 2017
Series 420
Pneumatic Control System
Type3416 IndicatorType3421 Compact Controller with Type3422
Controller Station and Type3423 Controller
Module
Type3417 Pneumatic
Control Unit
Type3427 Manual Control
Station
Type3425 Pneumatic
Controller (control room
installation)
Type3425 Pneumatic
Controller (eld unit)

2 EB 7500 EN
Note on these mounting and operating instructions
These mounting and operating instructions assist you in mounting and operating the device
safely. The instructions are binding for handling SAMSON devices.
ÎFor the safe and proper use of these instructions, read them carefully and keep them for
later reference.
ÎIf you have any questions about these instructions, contact SAMSON‘s After-sales Service
Department (aftersalesser[email protected]).
The mounting and operating instructions for the devices are included in
the scope of delivery. The latest documentation is available on our website
(www.samson.de) > Product documentation. You can enter the document
number or type number in the [Find:] eld to look for a document.
Denition of signal words
Hazardous situations which, if not avoided,
will result in death or serious injury
Hazardous situations which, if not avoided,
could result in death or serious injury
Property damage message or malfunction
Additional information
Recommended action
DANGER
!
WARNING
!
NOTICE
!
Note
Tip
Damage to health relating to the REACH regulation.
If a SAMSON device contains a substance which is listed as being a substance of very high
concern on the candidate list of the REACH regulation, this circumstance is indicated on the
SAMSON delivery note. Information on safe use of the part affected,
see uhttp://www.samson.de/reach-en.html.
WARNING
!

EB 7500 EN 3
Contents
1 General safety instructions.............................................................................5
2 Application ...................................................................................................6
3 Operation.....................................................................................................6
3.1 Settings at the controller modules ....................................................................6
3.1.1 Direction of action ..........................................................................................6
3.1.2 Air delivery ...................................................................................................7
3.1.3 Proportional-action coefcient KP ....................................................................8
3.1.4 Reset time Tn .................................................................................................8
3.1.5 Derivative-action time Tv .................................................................................8
3.1.6 Operating point .............................................................................................8
3.2 Adjusting the limit contacts .............................................................................9
4 Start-up and settings ...................................................................................10
4.1 Tuning the controller .....................................................................................10
4.2 Bumpless automatic/manual mode changeover ..............................................12
4.3 Readjusting the controller zero point ..............................................................12
4.4 Additional modules ......................................................................................12
4.4.1 Type3424-4 Manual/automatic Transfer .......................................................12
4.4.2 Type3424-5 Control Mode Changeover ........................................................12
4.4.3 Type3424-6 Signal Limiter ...........................................................................13
5 Design and principle of operation ................................................................14
5.1 Type3421 Compact Controller .....................................................................14
5.2 Type3427 Manual Control Station ................................................................16
5.3 Type3425 Pneumatic Controller (wall-mounted and eld controller) .................16
5.4 Type3416 Indicator .....................................................................................17
5.5 Type3417 Pneumatic Control Unit ................................................................17
5.6 Type3423 Controller Modules ......................................................................18
5.7 Additional modules ......................................................................................21
5.7.1 Type3424-2x for i/p conversion...................................................................21
5.7.2 Type3424-4 for bumpless manual/automatic switchover ................................22
5.7.3 Type3424-5 for control mode changeover.....................................................22
5.7.4 Type3424-6 for signal limitation ..................................................................22
5.8 Optional electrical limit contacts ....................................................................23

4 EB 7500 EN
Contents
6 Installation..................................................................................................24
6.1 Changing scales ..........................................................................................25
7 Connections ................................................................................................26
7.1 Pneumatic connections..................................................................................26
7.2 Electrical connections ...................................................................................28
8 Maintenance ...............................................................................................30
8.1 Checking the air supply ................................................................................30
9 Conversion..................................................................................................30
9.1 Changing the controller function ....................................................................30
9.2 Operating mode changeover in Type3424-2 i/p Converter ............................33
9.3 Checking the controller function ....................................................................34
10 Technical data.............................................................................................35

EB 7500 EN 5
General safety instructions
1 General safety instructions
−The device must be mounted, started up, or serviced by fully trained and
qualied personnel only; the accepted industry codes and practices are to
be observed. Make sure employees or third persons are not exposed to any
danger.
−All safety instructions and warnings given in these mounting and operating
instructions, particularly those concerning installation, start-up, and mainte-
nance, must be strictly observed.
−Devices with a CE marking have an EC declaration of conformity, which in-
cludes information about the applied conformity assessment procedure. The
EC Declaration of Conformity is available on request.
−According to these mounting and operating instructions, trained personnel
refers to individuals who are able to judge the work they are assigned to
and recognize possible dangers due to their specialized training, their
knowledge and experience as well as their knowledge of the applicable
standards.
−To ensure appropriate use, only use the device in applications where the op-
erating pressure and temperatures do not exceed the specications used for
sizing the device at the ordering stage.
−The manufacturer does not assume any responsibility for damage caused by
external forces or any other external factors.
−Proper transport, storage, installation, operation, and maintenance are as-
sumed.

6 EB 7500 EN
Application
2 Application
The Series420 Control System is used in au-
tomation applications in process engineering
and industrial plants. It can be used for ap-
plications with P, PI, PID, and PD controls, for
control loops with control mode changeover
or signal limitation, for xed set point, ratio,
cascade, or slave control.
The output signals of a connected transmitter
or master controller are measured as pneu-
matic standardized signals between 0.2 and
1bar or, in case of i/p additional modules,
0/4 to 20mA signals.
The integrated controller modules compare
the measured variable with the set point and
issue a corresponding pneumatic control sig-
nal of 0.2 to 1bar (2 to 15psi).
The controller requires a supply pressure of
1.4bar (20psi).
3 Operation
3.1 Settings at the controller
modules
The settings for direction of action and air
delivery must be performed prior to start-up.
Release the lock (4 in Fig.1) on the front
panel of the compact controller and pull the
manual control station completely out of the
housing to access the controller module.
3.1.1 Direction of action
The direction of action for the control loop is
set at the turnboard A. Tshe position of its
arrow symbol according to the arrow symbol
on the controller module determines the
direction of action of the controller (Fig.1).
< > Arrow tips facing opposite directions:
Direction of action increasing/decreas-
ing
As the controlled variable x increases,
the output pressure y falls.
>> Arrow tips facing the same direction:
Direction of action increasing/increas-
ing
As the controlled variable x increases,
the output pressure y increases.
Setting or changing the direction of action:
Unscrew the screw in turnboard A and lift it
off together with the turnboard. If necessary,
lever the board at the side. Do not lose the
rubber seal.
NOTICE
!

EB 7500 EN 7
Operation
− Turn the board by 90° so that the re-
quired arrow is aligned with the arrow
on the base plate.
− Insert board and tighten the screw.
3.1.2 Air delivery
(only with Type3423 Controller Module)
The position of turnboard B with its arrow
symbol determines the air delivery to the
feedback bellows.
>yA Normal air delivery,
approx. 1 mn³/h per % of the system de-
viation (default setting)
>R High air delivery,
approx. 3mn³/h per % of the system de-
viation (not with P or PD controller mod-
ules)
Setting or changing the air delivery
If the control valve that is to be controlled is
more than 15 meters away, increase the air
delivery by turning the position of turnboard
B from yA (standard) to R.
Fig.1: Turnboards and adjusters
1 Compact controller
2 Control room housing
3 Controller module
3.1 Comparator
3.2 Connecting plate
3.3 Hex screws
3.4 Screws (inside)
4 Lock
6 Fastening screw
7 Restriction
8Zero adjuster
9Kp adjuster
10 Tn adjuster
11 Tv adjuster (only in PD or PID
controller)
12 Operating point adjuster
(only in P or PD controller)
Turnboard
ADirection of action
BAir delivery
43
123.2 3
View from the side without
comparator (3.1)
Type3423-2 Controller Module (PI)
B
10
11
12
83.43.2 3.1 96A3.3
7

8 EB 7500 EN
Operation
1. Unscrew the fastening screw (6) at the
controller module and pull the module off
its self-seal push-on ttings.
2. Unscrew screws (3.3) and pull off the
connecting plate (3.2) together with
square nuts and bolts from the controller
module.
3. Unscrew the hexagonal socket head
screws (3.4) at the side and lift the com-
parator (3.1) off the controller module.
4. Unscrew the screw in turnboard B and lift
it off together with the turnboard. If nec-
essary, lever the board at the side. Do
not lose the rubber seal.
5. Turn the board so that the arrow is
aligned with yA or R on the controller
module. Insert board and tighten the
screw.
6. Remount the controller module and fas-
ten it in the controller station.
3.1.3 Proportional-action co-
efcientKp
The setting of the Kp (adjuster 9) determines
the controller gain and depends on the con-
trolled system that is to be tuned (see sec-
tion4.1).
3.1.4 Reset time Tn
Controller versions with integral-action com-
ponent require the reset time to be set at the
adjuster (10). The setting depends on the
controlled system that is to be tuned (see sec-
tion4.1).
3.1.5 Derivative-action time Tv
Controller versions with derivative-action
component require the derivative-action time
Tv to be set at the adjuster (11). The setting
depends on the controlled system that is to
be tuned (see section4.1).
3.1.6 Operating point
Controller modules without integral-action
component (e.g. P or PD, controllers) have
an operating point.
This can be adjusted at the operating point
adjuster (12) between 0 and 100%, which
corresponds to 0.2 to 1bar.
The setting depends on the output pressure y
that is to be tuned (see section4.1).
The Type3423-9 Controller Module does not
have an operating point adjuster. The oper-
ating point is dependent on the set point.

EB 7500 EN 9
Operation
Fig.2: Indicator with limit contacts
Adjustment screw
Indicator with
proximity switch
Lock
Limit adjuster in
Type3416
3.2 Adjusting the limit contacts
The listed limit contacts are no longer avail-
able.
InductivecontactsinType3422Manual
ControlStationandType3427Manual
Control Unit
−Release lock on the front panel and pull
out the indicating unit.
The proximity switches with min. and
max. contacts can be accessed through
the opening on the left-hand side.
−Use a 2.5 mm hex screwdriver to slightly
loosen the two fastening screws.
−Move the corresponding proximity switch
until the indicator points to the required
value on the reference scale and a con-
tact is made over the connected switch-
ing amplier or the LED on the front
lights up when contact is made.
−Retighten screws and place the marker
on the main scale at the corresponding
place.
Inductive and pneumatic contacts in
Type3416PneumaticIndicator
−Release lock on the front panel and pull
out the indicating unit.
−Move adjuster at the side until contact is
made.
Note

10 EB 7500 EN
Start-up and settings
4 Start-up and settings
Before start-up of the control loop, check all
devices to make sure that they are connected
correctly, do not leak, and function properly.
Release lock (7) and pull out the plug-in unit
of the compact controller station for easier
access to the operating controls at the con-
troller.
Check the turnboard to make sure the correct
direction of action is set at the controller (see
section3.1.1). Set arrow symbol (6) for
valve position at 100% signal pressure ac-
cordingly:
Arrow symbol facing:
Upward: valve OPEN
Downward: valve CLOSED
4.1 Tuning the controller
The controller needs to be tuned to the char-
acteristics of the controlled system using the
Kp and Tn and/or Tv adjusters at the control-
ler module (Fig.1) to ensure that the control-
ler can keep any system deviations for all set
points caused by the disturbance variables to
zero or at least minimize them.
The tuning test following the Ziegler and
Nichols method is a simple way to tune the
controller. In this method, the controller runs
in closed-loop operation with P action to the
point where it is still stable. It can only be
applied to controlled systems in which the
controlled variable can be made to hunt.
1. Set manual/automatic switch (10) to
manual. Apply supply pressure
(1.4±0.1bar) to Z.
2. Set the proportional-action coefcient Kp
to a low value (0.2) at the comparator.
PI and PID controllers only: set Tn restric-
tor to its maximum value (50 min) and Tv
to its lowest value (0.01 min).
3. Adjust the set point at the top rotary
knob (11) until the green pointer (2)
points to the required value on the scale.
PI and PID controllers:
4. Adjust the manual output yH at the bot-
tom rotary knob (9) to start up the con-
trol loop until the controlled variable in-
dicated by the red pointer (3) slowly ap-
proaches the adjusted set point (green
pointer).
Fig.3: Front view
1 Front panel
2 Set point pointer
3 Controlled variable
pointer
4 Control signal yA
5 Control signal yH
6 Valve CLOSED/OPEN
7 Lock
8LED
9Manual adjuster for yH
10 Manual/automatic
switchover
11 Set point adjuster
12 Label
2
4
3
5
1
12
10
11
9
7
8
6

EB 7500 EN 11
Start-up and settings
When the pointers meet, wait until also
the automatic output (4) on the bottom
scale reaches the manual output (5).
If necessary, slightly adjust the set point
to allow the automatic output to match
the manual output more quickly. After
they match, set the set point back to the
controlled variable. Continue as de-
scribed in 5.
P and PD controllers with operating point
adjuster:
−Set the manual/automatic switch to auto-
matic.
−Adjust the operating point at the operat-
ing point adjuster in the range between
0 and 100% until the controlled variable
(red pointer) is identical with the adjust-
ed set point (green pointer). Continue as
described in 6.
5. Change the manual/automatic switch to
automatic.
6. Starting from a low value, increase the
proportional-action coefcient Kp until
the red controlled variable pointer shows
an harmonic oscillation pattern of the
controlled variable (uniform oscillation
amplitudes as shown in Fig.4).
If oscillations do not arise with a large
Kp setting, turn the rotary knob to slight-
ly change the set point and then return it
to its former setting. It may be necessary
to increase the gain (Kp) slightly until an
harmonic oscillation pattern arises.
7. Write down the adjusted value on the Kp
scale you have just adjusted as the criti-
cal proportional-action coefcient Kp,
crit.
PI and PID controllers:
Use a stopwatch to time the oscillation
time for one entire oscillation to nd Tcrit.
Fig.4: Harmonic oscillation, settings
8. Multiply value for Kp,crit and value for
Tcrit (with PI/PID controller) with the val-
ues in the table (Fig.4) and set them as
the favorable settings for Kp, Tn, and Tv
at the controller.
Should oscillations still occur despite these
settings, slightly reduce Kp and increase Tn.
Repeat these steps, if necessary, until the
control loop shows a satisfactory perfor-
mance.
Leave enough time in between settings to al-
low the controller to stabilize.
If the set point (reference variable) of the P or
PD controller is changed, readjust the oper-
ating point. When the reference variable is
often changed, adjust the operating point to
an average value (e.g. 50%).
Con-
troller Kp Tn Tv
P 0.50·Kp,crit
PI 0.45·Kp,crit 0.85·Tcrit
PID 0.59·Kp,crit 0.50·Tcrit 0.12·Tcrit
Controlled
variable (ac-
tual value)
T
crit
Tcrit
–
+
Note

12 EB 7500 EN
Start-up and settings
If a P/PI controller is switched to P action,
completely open the Tn restrictor to ensure
the operating point adjuster can take effect
without delay.
Version with set-point-dependent operating
point
This version does not need to be adjusted
since the operating point automatically fol-
lows the set point w.
4.2 Bumpless automatic/
manual mode changeover
The bumpless switchover ensures that no
pressure surges can reach the valve when
the manual/automatic switch (10) is activat-
ed as follows:
Changeover from automatic to manual
Use the adjuster (9) to adjust the manual out-
put yH until the pointers (4 and 5) in the bot-
tom display meet. Change the switch over to
manual.
Changeover from manual to automatic
If the system is to be controlled manually to
the required value, the automatic output yA
must be adjusted at the set point adjuster
(11) to match the manual output yH.
The switch (10) can only be set to automatic
after the pointers (4 and 5) in the bottom dis-
play meet.
4.3 Readjusting the controller
zero point
If deviations arise between the controlled
variable and set point during operation, the
zero point can be readjusted by turning the
zero adjuster (8 in Fig.1) until the controlled
variable and set point on the front display
are the same again.
4.4 Additional modules
The Type3424 Additional Module is no lon-
ger available.
4.4.1 Type3424-4Manual/
automatic Transfer
Switchover is performed automatically by
activation of the manual/automatic switch
(10, Fig.3). See uT7523.
4.4.2 Type3424-5Control
Mode Changeover
uT7523
Adjusting the direction of action
Set the direction of action at the turnboard of
the control mode changeover device to
match the direction of action of turnboard A
of the controller module. To proceed, unfas-
ten the screw on the turnboard and turn the
board as follows:
Note
Note

EB 7500 EN 13
Start-up and settings
< > Increasing/decreasing:
Position (x-w) </= 0
> > Increasing/increasing:
Position (x-w) >/= 0
Setting the control error
The setting depends on the system and must
be determined by experimenting.
Starting with a high value, perform the set-
ting in steps with an increasingly smaller
control error.
To ensure that the switchover point for P and
PI or PD and PID control mode is not continu-
ously exceeded, set the control error (x–w),
keeping the error deviations that occur in the
system due to constant disturbances within
the adjusted (x–w) range.
It is often recommendable to set the control
error (x–w) to be double the Kp value set at
the controller module.
Setting the operating point
When the system is in a steady-state condi-
tion, move the operating point adjuster to the
value of the manual output yA (reading at
the manual control station) (0 to 100% cor-
respond to an output of 0.2 to 1bar).
In case of large and frequently changing ref-
erence variables, we recommend setting it to
50%.
Set-point-dependent operating point
In this version, the operating point is auto-
matically tracked, meaning that the system
deviation remains at zero. The set point ad-
juster allows, however, a proportional shift
of ±20%.
Feedback limitation
The additional feedback limitation allows the
output pressure yA to be limited. In this case,
the 0 to 100% scale of the adjuster corre-
sponds to a limitation signal of 0.2 to 1bar.
Fig.5: Type3424-5 Control Mode
Changeover
4.4.3 Type3424-6Signal
Limiter
Use the corresponding adjusters to perform
the minimum or maximum signal limitation
(Fig.13). In this case, the 0 to 100% scale
of the adjuster corresponds to a limitation
signal of 0.2 to 1bar. See uT7523.
Operating point
System
deviation
yA limiter
Direction of
action of
turnboard

14 EB 7500 EN
Design and principle of operation
Fig.6: Type3421 Compact Controller
1.1 Housing
1.2 Plug-in unit
1.3 Controller module
1.4 Connecting plate
2 Set point pointer (green)
3 Controlled variable pointer (red)
4 Control signal yA
5 Control signal yH
9Manual adjuster for yH
10 Manual/automatic switchover
11 Set point adjuster
14 Selector switch (wext/wintern)
5 Design and principle of oper-
ation
The pneumatic control system has a modular
design. As a result, the compact control
equipment can be combined with various
controller modules and additional modules
and adapted to a wide range of applica-
tions.
5.1 Type3421CompactCon-
troller
The Type3421 Pneumatic Compact Control-
ler consists of the Type3422 Manual Control
Station and the Type3423 Controller Mod-
ule.
The manual control station consists mainly of
the housing (1.1) with connecting plate (1.4)
and the plug-in unit (1.2) to hold the control-
ler module (1.3). The plug-in unit has self-
seal push-on ttings, allowing the device to
also function as a control station when no
other components are used.
The controlled variable and set point pointers
have metal bellows measuring elements. The
controlled variable measuring element can
optionally be equipped with adjustable in-
ductive limit contacts or LEDs.
Three versions of the Type3422 Manual
Control Station are available, which are
adapted to the control task. Depending on
the circuit version 1, 2 or 9, the device does
not have the set point adjuster (11), set point
pointer (2), or selector switch (14) for inter-
nal (wint) or external (wext) reference variable.
All circuit versions have the ports R (feed-
back) and y (output pressure) connected in-
ternally to the connecting plate of the com-
pact controller.
In case y and R are to be routed separately
out of the device, proceed as described in
section7.1 by relocating the O-rings on the
connecting plate.
1.4
1.1
1.31.2
149
5
4
3
2
10
11

EB 7500 EN 15
Design and principle of operation
Circuit version 1 for xed
set point and slave con-
trol
P/PI
P
PI
PID
PD
R
w
Z
yA
yA
y
H
yA
yH
yHx
S
S
S
y
A
w
Z
R
wext
wint
w
wx
wext
x
y
Circuit version 2 for slave
control
S
P/PI
P
PI
PID
PD
R
w
Z
yA
yA
y
H
yA
yH
yHx
S
S
y
A
w
Z
R
x
y
wext
wx
Circuit version 9 for ratio
control
P/PI
P
PI
PID
PD
Z
a
yA
y
H
yA
yH
yH
e
S
S
yA
w
Z
R
e
a
wext
x
x
y
Fig.7: Circuits of Type3421 Compact Controller
Pneumatic
connection
Self-seal push-on
tting
Supply air Z
Venting
Pneumatic adjuster
End connection
Manual/automatic
switch
yManipulated
variable
x Controlled variable
w Set point
wext External set point
wint Internal set point
R Feedback
yA Output pressure
yH Manual output
S Switching pressure
a Output pressure
eInput pressure

16 EB 7500 EN
Design and principle of operation
5.2 Type3427ManualControl
Station
The Type3427 Manual Control Station is
used in combination with the Type3425
Pneumatic Controller (in a Type3426 Con-
trol Room or Field Housing).
The three different versions (Type3427-1,
Type3427-2, and Type3427-9) are adapt-
ed to control tasks and corresponds to the
circuits of Type3422 Manual Control Sta-
tion. See uT7511.
5.3 Type3425PneumaticCon-
troller (wall-mounted and
eldcontroller)
The pneumatic controllers for control room or
eld installation consist of the Type3426
Control Room or Field Housing and a
Type3423 Controller Module.
The controller module is connected over self-
seal push-on ttings to the housing and fas-
tened with a screw (6). See uT7512.
6
P/PI
P
PI
PID
V
wext
wint
yA
yH
yA
yH
yA
yH
yA
yH
yH
w
xw
wext y
w
Z
y
y
y
S
x
R
R
w
Z
yAyA
S
x
wext
yA
yH
yH
xw y
w
Z
yA
S
x
R
R
w
Z
yA
S
x
wext
yA
yH
yH
xy
w
Z
yA
S
*)
*)
x
R
R
w
Z
yA
S
S
S
S
x
P/PI
P
PI
PID
V
Fig.8: Pneumatic manual control unit with controllers for control room and eld installation
6
Type3426-3 Field Housing with Type3423
Controller Module
Type3427-1 Manual Control Unit (circuit 1) connected
to Type3425 Pneumatic Controller (for control room
and eld installation)
Type3426-2 Control Room
Housing with Type3423
Controller Module
Type3427 Manual Control Station

EB 7500 EN 17
Design and principle of operation
Fig.9: Type3416 Indicator and Type3417 Pneumatic Control Unit
Type3416 Indicator in double and
single versions
Type3417 Pneumatic Control Unit
with signal adjuster, selector switch,
and indicators
5.4 Type3416Indicator
The pneumatic indicators are used when
connected to control equipment to display
measured variables (e.g. temperature or
pressure) in standardized pneumatic signals
from 0.2 to 1bar.
The devices are tted with double or quadru-
ple indicators depending on the control task.
Devices with electric or pneumatic limit con-
tacts have proximity switches or pick-offs
with emitter sensor nozzles, which are con-
nected to the limit contact pointers. The metal
tag connected to the measuring unit pointer
triggers a signal when a limit is reached. See
uT7526.
The listed limit contacts are no longer avail-
able.
5.5 Type3417Pneumatic
Control Unit
The Type3417 Pneumatic Control Unit is
used to adjust, link, and feedback pneumatic
signals in standardized range from 0.2 to
1bar.
The set-up of the individual versions varies in
the equipment of remote adjusters, signal se-
lector switches, and indicators which are in-
stalled in the housing depending on the con-
trol task. See uT7527.
Note

18 EB 7500 EN
Design and principle of operation
5.6 Type3423Controller
Modules
See uT7521. The controller modules are
plug-in units which are inserted onto the self-
seal push-on ttings of a manual control sta-
tion, manual control unit, or control room or
eld housing. The controller modules are
held in place by a screw.
The controller modules consist of a compara-
tor tted with four metal bellows arranged in
a square and a base plate with self-seal
push-on ttings.
The base plate accommodates the compo-
nents required for the chosen function, such
as relays and restrictors. The components
can be exchanged or upgraded, allowing
the function to be changed at a later point in
time (see section9.1).
Type3423-2PIController(Fig.10, top)
The controlled variable x and the reference
variable w (set point) are transferred as
pneumatic signals between 0.2 and 1bar
via turnboard A to the metal bellows w and
x. When x is greater than w, the controlled
variable bellows tilts the pivoted swashplate
toward the set point bellows, causing the
pressure downstream of the nozzle connect-
ed to the swashplate over a pin to rise. As a
result, the output pressure yA of the booster
increases. The pressure yA is fed back imme-
diately via turnboard B to the bellows R2 on-
to the swashplate.
The position of the swashplate and the out-
put pressure yA keep changing until the dis-
tance between nozzle and apper is the
same as initially and the output pressure yA
assumes a value corresponding to the con-
trolled variable x and the adjusted propor-
tional-action coefcient Kp adjustable over a
screw.
Outside of the controller module, the yA is
connected to R, allowing the pressure yA to
be fed back to bellows R1 also over the port
R and the adjustable Tn restrictor. As a re-
sult, the effects of the pressures in bellows R1
and R2 balance themselves out and the error
deviation is eliminated.
A switchover to manual mode at the control-
ler station causes a switching pressure to be
applied to port S. The Tn start-up relay is ac-
tivated and bypasses the Tn restrictor.
The turnboard A determines the direction of
action of the controller. The direction of ac-
tion can be changed by turning the turn-
board (see section3.1.1).
The turnboard B determines the air delivery
to the feedback bellows.
In the delivered state, the turnboard B is set
to yA, i.e. the output pressure yA is directly
fed back to bellows R2. Whereas, it is fed
via connection R to bellows R1. With this cir-
cuit arrangement, the controller provides
normal air delivery and output pressure
damping.
In the switching position to R, the output
pressure yA is fed back via port R to the bel-
lows R1 and R2. As a result, the controller
has a higher air delivery. Practical applica-
tion for long distances to the control valve,
large connecting volumes and for fast con-
trolled systems.
See section3.1.2 on how to set or change
the air delivery by turning the turnboard B.

EB 7500 EN 19
Design and principle of operation
Type3423-2PIControllerModule
The following controller module versions are
almost identical to the Type3423-2 PI Con-
troller Module, except they are tted with, for
example, an operating point adjuster, a de-
rivative element or a selector switch, de-
pending on the application.
Type3423-1PControllerModule
This module is largely identical to the
Type3423-2 PI Controller Module.
Type3423-3PIDControllerModule
This module is largely identical to the
Type3423-2 PI Controller Module.
This module, however, contains an addition-
al derivative element providing a deriva-
tive-action gain of approx. ten times in the
input branch of the controlled variable x.
The derivative-action time can be adjusted at
the TV restrictor.
Fig.10:Type3423 Controller Modules
R Feedback
R1/R2 Feedback
bellows
1.4bar supply
air
yAOutput pressure
SSwitching
pressure
Turnboards
ADirection of
action
B Air delivery

20 EB 7500 EN
Design and principle of operation
The Type3423-4PDControllerModuleis
similar to Type3423-4.
This module, however, contains a derivative
element providing a rate gain of the input
branch of the controlled variable x. It has a
derivative-action gain of approx. ten times
and a derivative-action time that can be ad-
justed at the TV restrictor.
The Type3423-5P/PIControllerModule
with P/PI selector switch can be used either
as P controller with operating point setting or
PI controller.
This module is designed in the same way as
the PI and P controller modules.
The Type3423-6 PD/PID Controller Module
with PD/PID selector switch can be used ei-
ther as PD or PID controller.
The Type3423-9PControllerModule with
set-point-dependent operating point is the
same as Type3423-1 P Controller Module,
except the operating point changes propor-
tionally to the set point w.
Type3423-7RatioRelay
This device is designed as the Type3423-1 P
Controller Module. The constant pressure of
the operating point adjuster, however, is fed
to the R1 and w bellows. The output pressure
a is proportional to the input pressure e (a =
e x Kp). In ratio control applications, this
pressure is the reference variable for a slave
controller.
Fig.11:Type3423 Controller Module