VEGA VEGABAR 44 HART - Manual (Page 4)

4 VEGABAR 44 (HART ® )
Product description
1 Product description
1.1 Function and configuration
VEGABAR 44 process pressure transmitters
are efficient instruments for process pres-
sure measurement. As pressure sensor
element, the dry ceramic-capacitive measur-
ing cell CERTEC
® is used. The process pres-
sure causes a capacitance change within the
measuring cell via the diaphragm. This ca-
pacitance change is detected by an ASIC
(Application specific integrated circuit) and
converted into a pressure-proportional signal
by the integrated sensor electronics with
microcontroller. Precise, high-resolution dig-
ital processing of measured data ensures
excellent technical data.
The electronics module is powered by a
separate VEGA signal conditioning instru-
ment, a stabilised power supply unit or a PLC
(active input). After the adjustment, a stand-
ardised 4 … 20 mA current signal is made
available which can be displayed (e.g. in
PLC systems) or further processed.
For carrying out adjustment, the following
alternatives are available:
- adjustment module directly on VEGABAR
- adjustment module in external housing
(VEGADIS 10)
- via PC with adjustment software VEGA
Visual Operating (VVO)
- with HART ® handheld
1.2 Self-monitoring
To improve reliability, the functionality of im-
portant electronic components is constantly
checked, and internal parameters such as
sensor value, temperature and operating
voltage are closely monitored.
VEGABAR 40 with ceramic CERTEC ® measur-
ing cell offers the advantage of continuous
self-monitoring. The measuring and reference
capacitances of the measuring cell constitute
a predefined ratio over the entire measuring
range. Any deviation from these data is a
reliable indicator of a malfunction of the meas-
uring cell.
If errors or malfunctions are detected during
these routines, the fault signal is triggered via
the 4 … 20 mA output (current jump to
3.6 mA or 22 mA).