VEGA VEGAPULS 45 VBUS - Manual (Page 5)

VEGAPULS 42, 44 and 45 – VBUS 5
Reflected radar power dependent on the dielectric
constant of the measured product
2
0
0
10
25 %
40 %
5
10
5 %
20
30
40
50
%
4 6 8 12 14 16 18
20
ε
r
t t
Time transformation
Product description
With standard flanges between DN 50 and
DN 150, ANSI 2" to ANSI 6" or G 1½ A and
1½" NPT the sensor antenna systems are
adapted to the various products and meas-
uring environments.
High quality materials withstand also extreme
chemical and physical conditions. The sen-
sors deliver reliable, precise and long-term
stable, reproducible level signals.
Continuous and reliable
Unaffected by temperature, pressure and
individual gas atmospheres, VEGAPULS
radar sensors are used for quick and reliable
continuous level measurement of various
products.
VEGAPULS radar sensors can accomplish
this through a special time transformation
procedure which spreads out the more than
3.6 million echo images per second in a slow-
motion picture, then freezes and processes
them.
Hence, it is possible for the VEGAPULS ra-
dar sensors to process the slow-motion
pictures of the sensor environment precisely
and in detail in cycles of 0.5 to 1 second
without using time-consuming frequency
analysis (e.g. FMCW, required by other radar
techniques).
Virtually all products can be measured
Radar signals are physically similar to visible
light. According to the quantum theory they
propagate through empty space and are
therefore not dependent, like e.g. sound
waves, on a conductive medium. And like all
electromagnetic waves, they travel at the
speed of light.
The radar signals react to two primary
electrical properties:
- the electrical conductivity of a substance.
- the dielectric constant of a substance.
All products which are electrically conductive
or have a dielectric constant greater than
ε
r
1.6 have sufficiently good reflection charac-
teristics for reliable radar measurement.
(Note: air has a dielectric constant
ε
r
of 1).
The signal reflection increases with the con-
ductivity or with the dielectric constant of the
product. Therefore virtually all products can
be measured.
Temperature influence: Temperature error absolutely
zero (e.g. at 500°C 0.018 %)
100 500 1000 1300 ˚C 0
0
0,01
0,02
0,03
%
0,018 %
0,023 %
Pressure influence: Error with pressure increase very
low (e.g. at 50 bar 1.44 %)
10
0
0
5
%
1,44 %
2,8 %
10
50
20 30 40 60
100
70 80 90 110 120 130 140
bar
0,29 %
3,89 %