VEGA WEIGHTRAC 31 4 … 20 mA_HART - four-wire - Manual (Page 51)

51
7 Setup with PACTware
WEIGHTRAC 31 • 4 … 20 mA/HART - four-wire
42374-EN-131119
Dynamic linearization
During dynamic linearization you simulate the actual operation of
the conveyor belt with the known material quantity. For a dynamic
linearization you need at least 20 % of the max. process value. If the
measuring range is e.g. 0 … 200 t, then at least 40 t of material should
be available for linearization.
As with zero point determination, the linearization will be more precise
the longer the linearization runs and the larger the filling height differ-
ences are. Hence, linearizations are often carried out with the max.
conveyed quantity, in our example with 200 t.
Tip:
During linearization many technical and process-related factors can
cause a faulty measurement. Therefore, have enough material ready
for the linearization so that, if necessary, you can repeat the measure-
ment.
•
You have a known quantity of material that is continuously loaded
onto the conveyor belt.
•
If possible, load the conveyor belt to maximum (100 %).
1. Load the conveyor belt continuously with a known quantity of
material.
Measure the material quantity with a belt weigher or weigh the
material with a truck scale.
Make sure that the material used corresponds to the material that
is measured later on.
2. Start the conveyor belt.
3. Click to "Start measurement", as soon as the first material passes
by the measuring point.
4. The run should last several minutes.
5. Click to "Stop measurement", as soon as the last material passes
the measuring point.
6. The measured count rate is stated in ct/s. This is the number of
counts per second, i.e. the measured radioactive radiation dose
actually reaching the sensor.
7. Now enter the corresponding material quantity (e.g. kg, t, lb). In
this case, this is the total quantity of material that has passed by
during the measurement.
This assigns a corresponding material quantity to the current
pulse rate.
8. Click to "Complete".
Accept the value pair with "Accept".
Carry out such a linearization with several different loading heights.
We recommend two to three measurements.
The measurement will be more reliable if you enter several lineariza-
tion points with different loading heights.