Operation Troubleshooting - Siemens 7ML5431 Operating Instructions Manual

Diagnosing and troubleshooting

10.4 Operation troubleshooting

10.4 Operation troubleshooting
Operating symptoms, probable causes, and resolutions.
Symptom
Display shows
Display shows
Display shows
Display shows
Reading does not
change, but the level
does
Measurement is con-
sistently off by a con-
stant amount
Screen blank
Reading erratic
172
Cause
level or target is out of range
material build-up on antenna
location or aiming:
poor installation
•
flange not level
•
Auto False Echo Suppression
•
may be incorrectly applied
antenna malfunction:
temperature too high
•
physical damage
•
excessive foam
•
multiple echoes
•
SITRANS LR250 processing
wrong echo, for example, vessel
wall, or structural member
setting for Low Calibration Pt.
•
(2.3.1.) not correct
setting for Sensor Offset
•
(2.3.3.) not correct
power error
too much load resistance
echo confidence weak
Action
check specifications
•
check Low Calibration Pt. (2.3.1.)
•
increase Confidence (2.8.6.1.)
•
clean the antenna
•
re-locate SITRANS LR250
•
check to ensure nozzle is vertical
•
ensure end of antenna protrudes from end of nozzle
•
review Auto False Echo Suppression (Page 238).
•
ensure Auto False Echo Suppression Range is set correct-
•
ly
check Current Internal Temperature (3.2.1.)
•
use foam deflector or stillpipe
•
relocate
•
use a defoamer
•
set Algorithm (2.8.4.1.) to F (First echo)
•
re-locate SITRANS LR250
•
check nozzle for internal burrs or welds
•
rotate device 90°
•
use Auto False Echo Suppression (2.8.7.1.)
•
if necessary: see Auto False Echo Suppression
•
(Page 238).
check distance from sensor reference point to Low Cali-
•
bration Pt. (2.3.1.)
check Sensor Offset (2.3.3.)
•
check nameplate rating against voltage supply
•
check power wiring or source
•
change barrier type, or
•
remove something from the loop, or
•
increase supply voltage
•
reduce wire distance or use larger gage wire
•
refer to Confidence (2.8.6.1.)
•
use Auto False Echo Suppression (2.8.7.1.) and Auto
•
False Echo Suppression Range (2.8.7.2.)
use foam deflector or stillpipe
•
Operating Instructions, 10/2019, A5E32220602-AG
SITRANS LR250 with mA/HART