Samson 430 Series, Mounting And Operating Instructions

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14 EB 7030 EN
Design and principle of operation
5.1 Transmitter modules
Type 3435 for pressure
The pressure p of the process medium is fed
to the transmitter module (2) where it creates
a movement at the bourdon tube measuring
system (2.1). The servo system (2.2) converts
this movement into a pneumatic signal (con
-
trolled variable x), which is proportional to
the pressure p. This signal is fed to the bel
-
lows measuring system of the controlled vari -
able display (1.3) and the controller module
(3).
Type 3436 for temperature with capillary
sensor
The temperature of the process medium pro -
duces a pressure proportional to the tem -
perature in the gas-filled sensor (2.3) of the
transmitter module. This pressure opposes a
force at the beam (2.4) which is generated
at the feedback bellows (2.6) by the output
pressure p
A
.
The supply air flows through the restrictor
(2.9) and nozzle (2.8) onto the flapper plate
(2.7). An increase in temperature causes the
flapper plate to come closer to the nozzle.
As a result, the output pressure p
A
applied to
the bellows (2.6) rises until a new equilibri -
um is reached, i.e. until the output signal
reaches a value proportional to the tempera
-
ture. The pneumatic standardized signal
(controlled variable x) is fed to the bellows
measuring system of the controlled variable
display (1.3) and the controller module (3).
Type 3438 for temperature with Pt 100
resistance thermometer
The Type 3438 Transmitter Module consists
of an electric transmitter and a downstream
i/p converter for connection to a Pt 100
resistance thermometer. The resistance value
of the Pt 100 sensor is converted into a 4 to
20 mA current signal in the electric
transmitter. Its output signal (4 to 20 mA) is
converted into a pneumatic signal (0.2 to
1 bar) by the i/p converter. The output
pressure proportional to the temperature is
applied as a pneumatic signal (controlled
variable x) to the bellows measuring system
of the controlled variable display and
controller module.