BERTHOLD TECHNOLOGIES LB 567, User Manual

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Chapter 4. Getting Started
54 MicroPolar 2 (++) LB 567
4.4
Commissioning the Chute
The moisture measurement on a chute is done using a fully as-
sembled measurement configuration with horn antennas. See
also
Figure 3-20 Typical measurement setup .
4.4.1 Components
The measurement setup on a measuring chute basically com-
prises the following components:
a pair of horn antennas (see chapter 3.7.4 )
a measuring chute, including assembly plate and horn an-
tenna holders
an evaluation unit
Two HF antenna cable, one HF reference cable and two RF
angle connectors
4.4.2 Measuring Geometry and Conditions
1. Measuring condition: electrically conductive materials
No metals or other materials with high conductivity must
be set up between transmitting and receiving antennas (in the
radiation field). Measuring pipes or chutes must also not be made
of conductive material; otherwise, they have to be provided with
an entrance window made of plastic, glass or ceramics. The
standard dimensions of these entrance windows have to be cho-
sen with regard to the antenna distance; for standard applica-
tions they have to be at least 15 x 15 cm up to 30 x 30 cm.
2. Measuring condition: Filling the chute
Bulk good has to be conveyed evenly through the measuring
chute, and it has to be ensured that the chute is filled completely
for the measurement. In some cases, it is advisable to accumu-
late the product, for example by using a slider installed below the
chute.
3. Measuring condition: Bulk density
The bulk density must not change with constant moisture.
A varying level in the feeder chute could be a possible cause for
the bulk density variation. Please take possible influence factors
into account. The measuring error resulting from bulk density
variations is proportional to the change.