Valmet Valmet MCA, Инструкция по установке и эксплуатации, Страница: 38 / 66

9.2. Sensitivity Correction
The sensitivity of Valmet MCA consistency measure-
ment is set according to the wood fiber. If the device
measures something else, the sensitivity may have to
be changed.
If the sensitivity of the measured material is previ-
ously unknown, the sensitivity must be determined
based on laboratory analysis. The lab results must be
from a sufficiently broad consistency area in order for
the sensitivity to be accurately determined. The results
of the analysis are plotted on the graph MCA vs.
Laboratory consistency, in which MCA is on the vertical
axis and laboratory consistency is on the horizontal
axis. The slope of the points on the graph is calculated
and it represents the MCA consistency measurement
sensitivity.
In the sample MCA vs. Lab graph in Figure 3 a linear
regression curve is plotted for the points. The slope of
the curve equation indicates the measurement sensit-
ivity, which is 0.89.
To go to the Sensitivity Correction menu, select
Special Functions/Sensitivity Corr. The following display
appears:
I n p u t n e w s e n s .
c o r r e c t i o n = 1 . 0 0
Press the Edit button and enter the sensitivity value
you determined for sensitivity correction. Press the
Save button to save the new value.
If you have to perform the sensitivity correction a
second time for some reason, you have to take into
account the existing sensitivity correction. This is done
by multiplying the new defined sensitivity by the existing
sensitivity coefficient and entering this result for the
new sensitivity coefficient value. For example, if the
sensitivity is defined again to be 0.9 after the correction
of the previous example the new sensitivity coefficient
is calculated: 0.9 x 0.89 = 0.8. If you want to cancel the
sensitivity correction, write 1 for the sensitivity coeffi-
cient value.
MCA vs Lab
y = 0,8932x + 0,291
2
2,2
2,4
2,6
2,8
3
3,2
3,4
3,6
3,8
2 2,2 2,4 2,6 2,8 3 3,2 3,4 3,6 3,8
Lab (%)
M
C
A
(%
)
Fig. 3. Calculating MCA measurement sensitivity.
Installation & Owner’s manual OUL00298 V2.3 EN 38 Valmet Mircowave Consistency Transmitter