BERTHOLD TECHNOLOGIES LB 567, Руководство пользователя

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Chapter 3. System Description
18 MicroPolar 2 (++) LB 567
3.4
Load Compensation
The microwave irradiates the product to be measured and detects
all changes in the product. Example conveyor belt, see Figure
3-2:
Figure 3-2:
Material profile on
the conveyor belt
flat surface
Horn antenna
Microwave beam
> 350 mm
The microwaves irradiate the entire material cross-section in the
radiation field. If the material layer thickness or the bulk density
changes (with constant moisture), then the microwave signals
will be affected. The goal of the load compensation is to compen-
sate for this influence. This is done by considering the two pa-
rameters layer thickness and bulk density which correspond to
the weight per unit area:
Load = weight per unit area [g/cm
2
] =
δ
∙ h Eq. 3-3
where:
δ
bulk density [g/cm
3
]
h material layer thickness [cm]
With load compensation, equation 3-1 is expanded as follows:
Measured value = A · Phase + G · Load + C Eq. 3-4
where:
Measured value Concentration / Moisture / Dry matter
A, G, C Coefficients of the calibration function
A weight per unit area compensation need not be performed
when the layer thickness and bulk density are constant in a fixed
measuring geometry. This is the case, for example, if conveyor
belts are always loaded with the same level, or if the filling level
in pipes or chutes is always the same, and the material has a
constant density.