Siemens SITRANS L Operating Instructions Manual page 177

Symptom
Reading does not
change, but the level
does
Measurement is con-
sistently off by a con-
stant amount
Screen blank
Reading erratic
Reading response slow Fill Rate (2.3.8.2.) setting incor-
Reads correctly but
occasionally reads high
when vessel is not full
Level reading lower
than actual material
level
SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH
Cause
SITRANS LR250 processing wrong
echo, for example, vessel wall, or
structural member
setting for Low Calibration
•
Point (2.3.7.1.) not correct
setting for Sensor Offset
•
(2.3.7.3.) not correct
power error
too much load resistance
echo confidence weak
liquid surface vortexed
material filling
rect
• detecting close range echo
• build up near top of vessel or
nozzle
• nozzle problem
• material is within Near Range
zone
• multiple echoes processed
• vessel near empty and low dK
material
Action
• re-locate SITRANS LR250
• check nozzle for internal burrs or welds
• rotate device 90°
use Auto False Echo Suppression (2.5.10.1.)
•
• if necessary: see Auto False Echo Suppression (Page 238)
check distance from sensor reference point to Low Cali-
•
bration Point (2.3.7.1.)
check Sensor Offset (2.3.7.3.)
•
• 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 (2.5.9.1.)
use Auto False Echo Suppression (2.5.10.1.) and Auto
•
False Echo Suppression Range (2.5.10.2.)
• use foam deflector or stillpipe
• decrease Fill Rate (2.3.8.2..)
• relocate device to side pipe
• increase confidence threshold in Echo Threshold (2.5.7.3.)
• Re-locate SITRANS LR250
• increase measurement response if possible
• clean the antenna
use Auto False Echo Suppression (2.5.10.1.) and Auto
•
False Echo Suppression Range (2.5.10.2.)
• decrease Near Range (2.5.1.) (minimum value depends on
antenna type)
• raise SITRANS LR250
ensure Algorithm (2.5.7.1.) is set to tF (First echo)
•
ensure Material (1.2.) selection is LIQUID LOW DK
•
• set Position Detect (2.5.7.2.) to Hybrid
check the setting for CLEF Range (2.5.7.4.): see the table
•
below Propogation Factor (2.5.3.) for recommended set-
tings
Diagnosing and troubleshooting
10.3 Operation troubleshooting
177