Barcon LHC/PPC (HART)
Introduction
8
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25.10.2001
1
Introduction
Application
The Barcon PPC and the Barcon LHC pressure transmitter measures the pressure of
gases, vapours and liquids and is used in all areas of chemical and process engineering.
Operating principle
Ceramic sensor
The system pressure acts directly on the rugged ceramic diaphragm of the pressure
sensor deflecting it by a maximum of 0.025 mm (0.0098 in). A pressure-proportional
change in the capacitance is measured by the electrodes on the ceramic substrate and
diaphragm. The measuring range is determined by the thickness of the ceramic
diaphragm.
Metal sensor
The process pressure deflects the separating diaphragm with a filling liquid transmitting
the pressure to a resistance bridge. The bridge output voltage, which is proportional to
pressure, is then measured and processed.
Fig. 1.1: Sensor construction
Measuring system
The complete measuring system consists of
•
Barcon pressure transmitter with 4 mA … 20 mA signal output with
superposed digital signal (HART communication) and
•
power supply 11.5 V … 45 V DC, in Ex area 11.5 V … 30 V DC.
Operation can be carried out via:
•
a digital display for operating and calling up measured values locally,
•
the universal handheld HART Communicator,
•
the Fuchs PACTware operating program.
Fig. 1.2: The measurement system
Electrode
Ceramic sensor
Metal sensor
Diaphragm
Ceramic substrate
Resistance
bridge
Filling fluid
Barcon
4 mA ... 20 mA
Non-Ex area:
11.5 V … 45 V DC
Ex-i area:
11.5 V … 30 V DC
Process
