VEGA VEGAPULS 41 Profibus PA - Manual (Page 24)

24 VEGAPULS 41 – Profibus PA
27292-EN-041227
Unfavourable
Mounting on a vessel with parabolic tank top
Correct
Unfavourable
Parabolic effects on dished or arched
vessel tops
Round or parabolic tank tops act like a para-
bolic mirror on the radar signals. If the radar
sensor is placed at the focal point of such a
parabolic tank top, the sensor receives am-
plified false echoes. The optimum mounting
location is generally in the range of half the
vessel radius from the centre.
Sensor too close to the vessel wall
If the radar sensor is mounted too close to
the vessel wall, strong false echoes can be
caused. Buildup, rivets, screws or weld joints
superimpose their echoes onto the product
i.e. useful echo. Please ensure a sufficient
distance from the sensor to the vessel wall.
Direct sensor vertically to the product surface
Correct Incorrect
Ladder
Ladder
Wrong orientation to the product
Weak measuring signals are caused if the
sensor is not directly pointed at the product
surface. Orient the sensor axis perpendicu-
larly to the product surface to achieve opti-
mum measuring results.
2.5 Common installation mistakes
Socket piece too long
If the sensor is mounted in a socket exten-
sion that is too long, strong false echoes
arise which interfere with the measurement.
Make sure that the horn antenna projects out
of the socket piece.
Flange antenna: Correct and unfavourable socket
length
Mounting and installation
Correct Unfavourable
Reference plane