T 7506 EN
Type 3421 Pneumatic Compact Controller
Series 420

Application
For panel mounting (front frame 72x144 mm)
Compact controller for automation of industrial and process plants · PI controller · Fixed set point, follow-up or cascade control

The compact controller is designed for input and output signals from 0.2 to 1.0 bar and for a supply pressure of 1.4 bar.
The controller meets special requirements of the processing industry.
Special features–– Compact controller with a mounting depth of 320 mm(400 mm installation depth)–– Set point, controlled variable and system deviation areeasy to read off the vertical 100 mm-long flat scale–– Adjusters, switches and displays can be operated from thefront–– Universal version, with standard selector switch wint/wext–– PI controller

Fig. 1: Type 3421 Compact Controller, front view–– Use in hazardous areas

Fig. 2: Type 3421 Compact Controller with Type 3422-1Controller Station

SAMSON AKTIENGESELLSCHAFT · Weismüllerstraße 3 · 60314 Frankfurt am Main, Germany
Phone: +49 69 4009-0 · Fax: +49 69 4009-1507 · samson@samson.de · www.samson.deEdition April 2019

Design and principle of operation
The Type 3421 Compact Controller consists of the Type 34221 Controller Station and Type 3423-2 PI Controller Module.
The Type 3422-1 Controller Station consists of a housing,plug-in unit with displays and operating controls as well as aflexible hose harness, which connects the plug-in unit to theconnecting plate. The plug-in unit, which can be released at
the lock and pulled out, is fitted with plug-on connections toaccommodate the controller module. These pneumatic connections are self-sealing when the controller module is pulled out.
–– Fig. 3 shows the displays and operating controls.
–– Fig. 4 shows the functional diagram with the pneumaticcircuit.
–– Fig. 5 shows the pneumatic connection.
The internal set point is adjusted at the set point adjuster (5).
The external set point (with an input signal of 0.2 to 1 bar) isfixed and input at connection wext. The selector switch wint/wext(13) is used to select the internal or external set point. The internal set point wint is selected in the delivered state. The selector switch wint/wext (13) is accessible after releasing the lock(11) and pulling the plug-in unit (1.2) out of the housing (1.1).
The set point can be read at the set point display (4). The controlled variable is supplied as a 0.2 to 1 bar input signal at
the connection x and displayed at the controlled variable dis-2

play (3). Set point and controlled variable are displayed on ascale with 0 to 100 % range or with a physical measuring
range. The manual/automatic switchover (6) is used to selectthe manual or automatic mode. The manual output pressure(yH) is set at the adjuster (7) and displayed at the display (9).
The automatic output pressure (yA) is shown at the display (8).
Both output pressures are shown on a scale ranging between
0 and 1.2 bar. The signal pressure is issued at the connection
y. The arrow symbol (12) is used to indicate the OPEN or
CLOSED valve position at 100 % signal pressure.
After releasing the lock (11) and pulling the plug-in unit (1.2)
out of the housing (1.1), the selector switch wint/wext (13) canbe operated and the direction of action can be changed at theturnboard A (22) and the proportional-action coefficient Kp(25), reset time Tn (26) and controller zero (24) can be set atthe corresponding adjusters.
The device is supplied with a supply pressure of 1.4 bar atconnection Z. After pulling out the plug-in unit, the supplypressure can be tested at the test connection Xtest (21) using theyellow test connector included in the scope of delivery to connect a pressure gauge using a hose with 2 mm inside diameter.

151

Type 3422-1 Controller Station

1.1 Housing
1.2 Plug-in unit
1.3 Hose harness

463
712811913

21

2224251.1

1.4 Connecting plate
2Label3Controlled variable display (x)4Set point display (w)5Set point adjuster

6

Manual/automatic switch

7

Adjuster for manual mode

8

Automatic output pressure (yA) display

9

Manual output pressure (yH) display

11Lock12

Arrow symbol to indicate the OPEN or
CLOSED valve position at 100 % signal
pressure

13

wint/wext selector switch

20Type 3423-2 Controller Module

21 Test connection for supply pressure
22 Turnboard A for direction of action
23 Restriction with filter
24 Adjuster for controller zero
25

1.2

20

23

1.3

26

1.4

Adjuster for proportional-action
coefficient Kp

26 Adjuster for reset time TnFig. 3: Type 3421 Compact Controller, with the plug-in unit pulled out of the housing

2T 7506 ENType 3421 Compact Controller

x w

wextwintw

Design and use of Type 3422 Controller StationRyAw
Sw

ZyHyAyH

Z

PI

yA

yA
yH

Type 3422-1 Controller Station
With Type 3423-2 Controller Module
For fixed set point and follow-up control
Can be used as master or slave controller incascade control

SRS

wext

xxy

Symbols for schematic diagram
Pneumatic connection

Supply air

Pneumatic adjuster
Manual/automatic switch

Plug-on connection

Venting

Blind connectionControl circuits with Type 3421 Compact Controller (schematics)
Fixed set point control

Follow-up control

1121wextx

Cascade control

x

2yy

3321x

2.1 ywext
2x

1

Pneumatic transmitter

2

Type 3421 Compact Controller

2.1 Master controller
2.2 Slave controller

2.2 y33Control valvexControlled variable (actual value)
input

wext

External reference variable(external set point) inputy

Output pressure

Fig. 4: Control applications

Installation and connections
Two rails are used to fasten the controller in the control panel. Pneumatic line connections: threaded holes 1/8 NPT in the connecting
plateType 3421 Compact Controller

1.4100Connections:

9080

137.5

1447060
40302010072320Syw

ZRwextxyA

Panel cut-out 138 +1 x 68 +0.7 mm
Distance between center lines:
Min. 73 or 170 mm

25S

Binary output manual/automatic modew

Reference variable (set point) output

RFeedbackx

Controlled variable (actual value) input

yA

Automatic output pressure

CSupply

wext

External reference variable (external setpoint) input

yOutput pressure

1.4Connecting plate for pneumaticconnections

Seal unused connections with the threaded plugs
included in the scope of delivery.

Fig. 5: Dimensions in mm and connections

T 7506 EN3

Technical data · Type 3421 Compact ControllerType 3421 Compact Controller
Controller station

3422-1

Set point/controlled variable display

2 metal bellows pressure gauge, upright · Signal range: 0.2 to 1 bar · Accuracy class 1 (synchronism 0.6)
Scale inscription: 0 to 100 % or special inscription with physical measuring range; length: 100 mm
2 bourdon tube pressure gauges, horizontal · Signal range: 0 to 1.2 bar · Accuracy class 2.5
Scale inscription: 0 to 1.2 bar; length: 36 mm

Output display

Output signal 0.2 to 1 bar · Max. 0.02 to 1.35 bar
Max. air delivery >1.5 mn³/h · Air consumption depending on adjuster: 0.1 mn³/h

Adjuster for manual output pressure
Type
Controller
module3423-2Controller action

PI

Control parameters

Proportional-action coefficient Kp = 0.2 to 20 · Reset time Tn = 0.03 to 50 min.

Input signal

0.2 to 1 bar

Output signal

0.2 to 1 bar · Max. 0.02 to 1.35 bar
Supply air 1.4 ±0.1 bar · Air consumption per unit <0.15 mn³/h

Supply air
Air quality acc. to ISO 8573-1

Maximum particle size and density: Class 3 · Oil content: Class 2Pressure dew point: Class 3 or at least 10 K below the lowest ambient temperature to be expected

Permissible ambient temperature−20 to +60 °C

Pressure Equipment Directive

2014/68/EU, Article 4.3 (sound engineering practice)Compliance
WeightApprox. 3.2 kg

Use in hazardous areas
The Type 3421 Compact Controller is suitable for use inhazardous areas of Zone 1 and 2 without its own EU-type
examination certificate. A EU-type examination certificateaccording to 2014/34/EU (ATEX Directive) is not required.

Ordering textWith Type 3422-1 Controller Station for 0.2 to 1 barWith Type 3423-2 PI Controller Module

Scale inscription: specify range and unit.

Specifications subject to change without notice

T 7506 EN

2019-04-29 · English–– Type 3421 Compact Controller