Siemens Milltronics BW500, Руководство по эксплуатации

Страница: 94 / 220

Recalibration
7.7 Linearization
BW500 and BW500/L
92
Operating Instructions, 12/2016, A5E33482052-AD
7.7 Linearization
Conveyor applications where the ideal belt scale location has been compromised, or where
there is a high degree of variation in belt tension, typically cause the belt scale to report load
non-linearly. The BW500 and BW500/L provides a linearizing function (P390 - P392) to correct
for the deficiency in the weighing system and to provide an accurate report of the actual process.
To verify that the cause of the non-linearity is not mechanical:
● Run the conveyor belt empty and stop it.
● Lift the belt off of the scale and suspend various test weights to the scale. If the load reported
by the BW500 and BW500/L is non-linear, a mechanical problem is indicated. Refer to the
belt scale manual to resolve the non-linearity by improved installation or repair.
If it is determined that the non-linearity is due to the weighing application, and not the actual belt scale,
apply linearization by performing the following:
● zero calibration
● span calibration at 90 to 100% of design rate
● material tests at 90 to 100% of design rate
● manual span adjust if required
● material tests at 1 to 5 intermediary flow rates where compensation is required.
Note
Compensation points must be at least 10% of the design load apart.
● calculate the percentage compensation for each flow rate tested.
%compensation = (actual weight - totalized weight * 100)/totalized weight
where:
actual weight = material test
totalized weight = BW500 and BW500/L total
Note
•
After the compensation has been programmed into the BW500 and BW500/L, a material
test should be run to verify the effect of linearization.
• If additional compensation is required, it must be based on new material tests performed
with the linearization turned off (P390 = 0).
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,