Rectify Faults - Siemens SITRANS LG270 Operating Instructions Manual

Reaction when malfunc-
tions occur
Procedure for fault recti-
fication
Check the 4 ... 20 mA
signal
Treatment of measure-
ment errors
PBD-51041066
Code Cause
Text mes-
sage
M505 – Level echo can no longer
be detected
No echo avail-
able
8.4

Rectify faults

The operator of the system is responsible for taking suitable meas-
ures to rectify faults.
The first measures are:
•
Evaluation of fault messages, for example via the display and
adjustment module
•
Checking the output signal
•
Treatment of measurement errors
A PC with the software PACTware and the suitable DTM or the soft-
ware PDM with a suitable DD offer further comprehensive diagnostics
options. In many cases, the reasons can be determined in this way
and faults can be rectified.
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 remove them:
Error
4 ... 20 mA signal
not stable
4 ... 20 mA signal
missing
Current sig-
nal greater than
22 mA or less
than 3.6 mA
The below tables show typical examples for application-relevant
measurement errors. There are two measurement errors:
SITRANS LG270 - Operating Instructions
Cause Rectification
– Fluctuations of – Set damping according to the
the measured instrument via the display and
variable adjustment module or PACTware/
DTM
– Electrical con- – Check connection according to
nection faulty chapter "Connection steps" and
if necessary, correct according to
chapter "Wiring plan"
– Voltage supply – Check cables for breaks; repair if
missing necessary
– Operating volt- – Check, adapt if necessary
age too low or
load resistance
too high
– Electronics – Exchange the instrument or send it
module in the in for repair
sensor defec-
tive
Rectification
– Clean the antenna
– Use a more suitable
antenna/sensor
– Remove possible false
echoes
– Optimize sensor position
and orientation
67