Vega VEGAPULS 64 - Measurement error with constant level

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9 Diagnosis, asset management and service
VEGAPULS 64 • Two-wire 4 … 20 mA/HART
51141-EN-210219
The below tables show typical examples of application-related meas-
urementerrorswithliquids.Themeasurementerrorsaredierentiated
according to the following:
•
Constant level
•
Filling
•
Emptying
The images in column " Error pattern" show the real level as a broken
line and the level displayed by the sensor as a continuous line.
1
2
Level
time
0
Fig. 46: Display of error images
1 Real level
2 Level displayed by the sensor
Note:
If the output level is constant, the cause could also be the fault setting
of the current output to " Hold value".
If the level is too low, the reason could be a line resistance that is too
high
Measurement error with constant level
Fault description Cause Rectication
Measured value
shows a too low or
too high level
Level
time
0
Min./max. adjustment not correct Adapt min./max. adjustment
Incorrectlinearizationcurve Adaptlinearizationcurve
Installation in a bypass tube or standpipe,
hence running time error (small measure-
ment error close to 100 %/large error close
to 0 %)
Check parameter "Application" with respect
to vessel form, adapt if necessary (bypass,
standpipe, diameter).
Measured value
jumps towards 0 %
Level
time
0
Multiple echo (vessel top, medium surface)
with amplitude higher than the level echo.
Check parameter "Application", especially
vessel top, type of medium, dished bottom,
high dielectric constant, and adapt if nec-
essary.
Treatment of measure-
ment errors with liquids