Measuring Cell For Level; System Configuration - Siemens SITRANS P Operating Instructions Manual

Description

4.5 System configuration

4.4.2.7

Measuring cell for level

①
②
③
④
⑤
⑥
Figure 4-13
● The inlet pressure (hydrostatic pressure)
through the seal diaphragm on the mounting flange
● The differential pressure at the measuring cell is transmitted to the differential pressure
sensor
● When measuring limits are exceeded, the overload diaphragm
the seal diaphragms
thus protect the differential pressure sensor
● The seal diaphragm
the resistance of the four doped piezoresistors in the bridge circuit.
● The change in the resistance causes a bridge output voltage proportional to the differential
pressure.
4.5 System configuration
Introduction
The pressure transmitter can be used in a number of system configurations:
● As a stand-alone version, supplied with the necessary auxiliary power
● As part of a complex system environment, e.g. SIMATIC S7
38
Inlet pressure P
+
Seal diaphragm on the measuring cell
Pressure cap
O-ring
Differential pressure sensor
Measuring cell body
Function chart of the measuring cell for level
⑤
through the seal diaphragms
② ⑫
or
②
is displaced by the differential pressure. The displacement changes
⑦
Overload diaphragm
⑧
Inlet pressure P
⑨
Filling liquid of the measuring cell
⑩
Capillary tube with the fill fluid of the mounting
flange
⑪
Flange with a tube
⑫
Seal diaphragm on the mounting flange
①
works hydraulically on the measuring cell
⑫
②
and the filling liquid
rests on the measuring cell body
⑤
from overload.
Operating Instructions, 11/2019, A5E44852162-AC
-
.
⑨
.
⑦
is displaced until one of
⑥
. The seal diaphragms
SITRANS P320/P420 with 4 to 20 mA/HART
②