Vega VEGAPULS 64 Operating Instructions Manual page 59

Check the 4 ... 20 mA
signal
Treatment of measure-
ment errors with liquids
VEGAPULS 64 • HART and accumulator pack
Connect a multimeter in the suitable measuring range according to
the wiring plan. The following table describes possible errors in the
current signal and helps to eliminate them:
Error
4 ... 20 mA signal not
stable
4 ... 20 mA signal miss-
ing
Current signal greater
than 22 mA, less than
3.6 mA
The below tables show typical examples of application-related meas-
urement errors with liquids. The measurement errors are differentiated
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.
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"
•
If the level indication is too low, the reason could be a line resist-
ance that is too high
9 Diagnosis, asset management and service
Cause
•
Fluctuating measured
value
•
Electrical connection
faulty
•
Voltage supply missing
•
Operating voltage too
low, load resistance
too high
•
Sensor electronics
defective
Rectification
•
Set damping
•
Check connection, cor-
rect, if necessary
•
Check cables for
breaks; repair if neces-
sary
•
Check, adapt if neces-
sary
•
Exchange the instru-
ment or send it in for
repair
1
2
time
59