7ML19981CM01.1
MERCAP – INSTRUCTION MANUAL
Page 37
Example 2
In this situation, the capacitance values are known in advance.
1.
Switch on the 275 and establish connection with the MST9500.
a.
Select:
Online
b.
Select:
Device set-up
c.
Select:
Diag service
d.
Select:
Calibration
e.
Select:
Enter values
f.
Select:
PV LRV
2.
Enter required capacitance value for 0% of the range
a.
Select:
PV URV
3.
Enter required capacitance value for 100% of the range
a.
Select:
Send (the values are now sent)
Example 3
In this situation, the capacitance values are not known and the level of the product can not be
set to 0% and 100%. To do this it is necessary to perform a number of measurements of the
capacitance value at various levels. These values can be read in
%
with the 275
communicator.
1.
Switch on the 275 and establish connection with the MST9500.
a.
Select:
Online
b.
Select:
PV
The measured value can be read continuously, even if current loop value is min. or max.
2.
Write down the measured value in pF with the corresponding level. Suppose the
following results were recorded:
a.
at 17% the measured PV value was 52 pF
b.
at 79% the measured PV value was 181 pF
This results in a difference of (181-52)/(79-17)=2.08 pF per %.
c.
17% means 17 * 2.08 = 35.37 pF.
d.
For 0% the capacitance value has to be 52-35.37=16.62 pF.
e.
100% is 100 * 2.08=208 + 16.62 = 224.6 pF.
With these calculated values, the MST9500 can be adjusted as described in Example 2
Example 2
Example 2
Example 2. The
more accurately the values are measured at 0%, and, respectively, at 100%, the more
accurate the final result will be.
Siemens Automation
