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9 Diagnosis, Asset Management and service
VEGAPULS SR 68 • 4 … 20 mA/HART two-wire
38294-EN-130624
Error
Cause
Rectification
4 … 20 mA signal
not stable
– Fluctuations of
the measured
variable
– Set damping according to the
instrument via the display and
adjustment module or PACTware/
DTM
4 … 20 mA signal
missing
– Electrical con-
nection faulty
– Check connection according to
chapter "
Connection steps
" and
if necessary, correct according to
chapter "
Wiring plan
"
– Voltage supply
missing
– Check cables for breaks; repair if
necessary
– Operating volt-
age too low or
load resistance
too high
– Check, adapt if necessary
Current sig-
nal greater than
22 mA or less
than 3.6 mA
– Electronics
module in the
sensor defec-
tive
– Exchange the instrument or send it
in for repair
The below tables show typical examples for application-relevant
measurement errors with bulk solids. There are two measurement
errors:
•
Constant level
•
Filling
•
Emptying
The images in column "
Error pattern
" show the real level with a bro-
ken line and the level displayed by the sensor as a continuous line.
1
2
Level
time
0
1 Real level
2 Level displayed by the sensor
Notes:
•
Wherever the sensor displays a constant value, the reason could
also be the fault setting of the current output to "Hold value"
•
In case of a too low level indication, the reason could be a line
resistance that is too high
Treatment of measure-
ment errors with bulk
solids
