PL-565 Accumass BW500 Page 55
Recalibration
Example :
A non-linearity with respect to the ideal response exists in a belt scale application
with design rate of 200 t/h. It is decided to do material tests at 15, 30 , 45, 60 and
75% of the design load. After performing a zero and a span calibration at 100% of the
design load, followed by material tests and manual span adjust, five material tests
were performed at 30, 60, 90, 120 and 150 t/h, as indicated by the BW500. The
following data was tabulated. (This example is exaggerated for emphasis).
The material tests should be run at same belt speed, representative of normal
operation; in this case 1.2 m/s. For each rate, record the corresponding load value by
scrolling to the BW500 load display during running conditions or by calculation.
load = rate
speed
BW500 load material test BW500 total compensation*
kg/m tonnes tonnes %
6.94 2.5 2.8 -10.7
13.89 5.0 4.5 11.1
20.83 7.5 7.9 -5.1
27.78 10.0 9.2 8.7
34.72 12.5 13.3 -6.0
*calculation example: % compensation = 2.5 – 2.8 x 100
2.8
= - 10.7
actual weight per material test
totalized weight by BW500
belt scale response
linearized BW500 response
internal response 100% - 150% of span
% compensation
span (100%)
-6.0
♦
-5.1
♦
-10.7
♦
11.1
♦
8.7
♦
Weight = Tonnes
Load – kg / m
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