VEGA VEGASON 54P…56P Profibus PA - Manual (Page 15)

VEGASON 54P … 56P 15
At greater distance, the energy of the ultra-
sonic impulses distributes over a large 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 (e.g. pipes and struts)
within the 100 % area of the emission cone.
The following illustration of the ultrasonic
beams is simplified and represents only the
main beam - a number of additional weaker
beams exists.
Min. distance, max. measuring range, span and reference plane
max. meas. distance 25 m (type 54), 45 m (type 55), 70 m (type 56)
2.2 General installation instructions
Measuring range
Beside other criteria, you select your instru-
ment according to the required measuring
range. The reference plane for the min. and
max. distance to the liquid or solids is the
transducer end, or for instruments in flange
Mounting and installation
version, the instrument flange (version A).
Please note the information on the reference
planes in chapter "7.4 Dimensions". The max.
filling depends on the required min. distance
and the mounting location.
Span
min. distance
1.0 m
min. distance 0.8 m
Reference plane
Beam angle and false echoes
The ultrasonic impulses are focused by the
transducers. The impulses leave the trans-
ducer in a conical form similar to the beam
pattern of a spotlight. The beam angle is 4°
(VEGASON 54), 5° (VEGASON 55) and 6°
(VEGASON 56) at -3 dB emitted power.
Any object, e.g. tubes or struts inside this
emission cone will cause a large false echo.
Especially within the first few meters of the
emission cone, pipes, struts, or other installa-
tions can interfere with the measurement. 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.
max. meas. range
0 %
100 %
Span
0 %
100 %
Span
0 %
100 %
min. distance 1.4 m
Reference plane