Principle Of Operation - Vega VEGABAR 51 Operating Instructions Manual

Supplementary label
"Oil and grease-free for
oxygen applications"
Application area
Functional principle
Power supply and bus
communication
VEGABAR 51 • Profibus PA
Instrument type
l
Article number instrument
l
Technical data: Measuring range, process pressure, process
l
temperature, signal output, voltage supply, protection, protection
class
Order number
l
Article numbers, documentation
l
Serial number
l
The serial number allows you to access the delivery data of the
instrument via www.vega.com, "VEGA Tools" and "serial number
search". In addition to the type label outside, you can also find the
serial number on the inside of the instrument.
Instruments in the version "Oil and grease-free for oxygen applica-
tions" are equipped with a supplementary label. The supplementary
label contains instructions on oil and grease-free parts of the
instrument.

3.2 Principle of operation

The VEGABAR 51 is a pressure transmitter with isolating diaphragm
for pressure measurement of highly corrosive and hot liquids.
The sensor element for measuring ranges up to 60 bar is the
®
CERTEC measuring cell with rugged ceramic diaphragm. The
hydrostatic pressure of the product or the process pressure causes a
capacitance change in the measuring cell via the metal process
diaphragm and the isolating system. This change is converted into a
corresponding output signal.
The sensor element for measuring ranges from 100 bar is a wire strain
gauge (DMS) on the rear of the process diaphragm. There, the
process pressure causes a resistance change, which is converted into
an appropriate output signal.
Power supply via the Profibus DP/PA segment coupler or VEGALOG
571 EP cards. A two-wire cable according to Profibus specification
serves as carrier of both power and digital data transmission for
multiple sensors. The instrument profile of VEGABAR 51 corresponds
to profile specification version 3.0.
The backlight of the indicating and adjustment module is powered by
the sensor. Prerequisite is a certain level of operating voltage.
The data for power supply are specified in chapter "Technical data".
1)
The isolating system protects the sensor against corrosive products and
high temperatures. By selecting suitable diaphragm materials and isolating
liquids, systems with a temperature resistance up to 400 °C (752 °F) can be
achieved.
3 Product description
1)
9