VEGA VEGAPULS 45 VBUS - Manual (Page 15)

VEGAPULS 42, 44 and 45 – VBUS 15
15 m
0 m
4,0 2,3 4,0 2,3 0
25%
m
25˚
18˚
50%
Emission cone of a VEGAPULS 42 with screw-on
antenna and with ø 40 mm horn
10 m
0 m
3,50 1,90 3,50 1,90 0
25%
m
30˚
22˚
50%
Meas.
distance
Emission cone of a DN 50 flange antenna
Meas.
distance
Mounting and installation
VEGAPULS 44 with
ø 48 mm horn
Emission cone and interfering reflec-
tions
The radar signals are focused by the an-
tenna system. The signals leave the antenna
in a conical path similar to the beam pattern
of a spotlight. The form and intensity of the
emission cone depend on the antenna used.
Any object in this beam cone causes a reflec-
tion of the radar signals. Within the first few
meters of the beam cone, tubes, struts or
other installations can interfere with the meas-
urement. At a distance of 6 m, the false echo
of a strut has an amplitude nine times greater
than at a distance of 18 m.
At greater distances, the energy of the radar
signal distributes itself over a larger area,
thus causing weaker echoes from obstruct-
ing surfaces. The interfering signals are
therefore less critical than those at close
range.
If possible, orient the sensor axis perpen-
dicularly to the product surface and avoid
vessel installations within the 100 % area of
the emission cone, e.g. tubes or struts.
The illustrations of the emission cones are
simplified and represent only the main beam
- a number of weaker beams also exist. Un-
der difficult measuring conditions, the align-
ment of the antenna must be such that the
lowest possible false echo values appear.
Only giving attention to the size of the useful
echo is not always adequate when measur-
ing conditions are unfavourable.
In a difficult measurement environment,
searching for a mounting location with the
lowest possible false echo intensity will bring
the best results. In most cases, the useful
echo will then be present with sufficient
strength. With the adjustment software VVO
on the PC, you can have a look at the echo
image and optimise the mounting location
(see chapter "5.2 Adjustment with the PC –
Sensor optimisation – Echo curve").
If possible, provide a "clear view" to the prod-
uct inside the emission cone and avoid ves-
sel installations in the first third of the
emission cone.
Optimum measuring conditions exist when
the emission cone reaches the measured
product perpendicularly and when the emis-
sion cone is free of obstructions.
VEGAPULS 42