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The capacitance value for a 17% change in level is 17 * 2.08 = 35.37 pF.
The capacitance value for 0% is 52 – 35.37 = 16.62 pF (initial capacitance value).
The capacitance value for 100% is (100 * 2.08) + 16.62 = 208 + 16.62 = 224.6 pF.
3.
Enter the calculated values for 0% and 100%, to calibrate the SITRANS LC500 as
described in Example 2.
Example 4
For situations involving the re-adjustment of the LRV where the actual value is
determined to be one value but the measurement shows a different value.
1.
Switch on the 275 and establish connection with the SITRANS LC500.
a. Select: Online
b. Select: PV
The measured value can now be read continuously.
2.
Write down the measured value in pF: assume it is 80 pF.
Example:
Assume that the URV is set to 240 pF, that the actual value is 17%, but the
measurement is showing a different value.
the measured value = 80 pF
(100 – 17) %
(240 – 80) pF
160 pF
83%
The capacitance value for 100% (URV) is 100 * 1.927 = 192.7pF
The new LRV should be 240 –192.7
3. Adjust URV and LRV by following the steps in Example 2.
If the DCS and/or the 275 are fitted with the Device Descriptor for the SITRANS LC500,
more functions can be used.
The available functions are
Number
Description
(48)
Read Additional Transmitter Status
(38)
Reset Configuration Changed Flag
(128)
Set Alarm Select
(129)
Adjust for Product Build-up on Sensor
Page 48
SITRANS LC500 – OPERATING INSTRUCTIONS
= 83%
= 60 pF
= 1.927 pF per %
:
= 47.22 pF.
7ML19985GE04
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