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Sometimes, in case of tank level measurement, it becomes difficult to calculate the LRV or the URV of the transmitter, or to empty
the tank for zero adjustment. So, not only with flange-mounted, but also with differential pressure transmitters using remote seals,
the Output % Reranging operation helps the user during transmitter calibration.
When it is know the level of the tank, expressed in percentage, the liquid level, it is possible to input this percentage that
automatically the transmitter recalculates its LRV and URV according to the new percentage value.
This can be done using a HART configuration tool on a 600T EN Transmitter, in HART version.
Two options are available as Output % Reranging operation:
1)
OP Range Low
where both LRV and URV are adjusted
2)
OP Range High
where only URV is change in accordance with the new input percentage
As example:
ADDENDUM FOR OUTPUT % RERANGING
Actual level measured by the transmitter:
Transmitter output
= 27%
Calibration :
LRV
= -125 mbar
URV
= +340 mbar
a) New input level measurement (Option 1) = 30%
New calibration : LRV
= -139.5 mbar
URV
= +325.5 mbar
The transmitter output is now = 30%
Starting again from the initial settings:
Transmitter output
= 27%
Calibration :
LRV = -125 mbar
URV = +340 mbar
b) New input level measurement (Option 2) = 30%
New calibration : LRV
= -125 mbar
URV
= +291.5 mbar
The transmitter output is now = 30%
