Siemens Sitrans LR250 User Manual

Diagnosing and troubleshooting
10.4 Operation troubleshooting
SITRANS LR250 (PROFIBUS PA)
176 Operating Instructions, 08/2014, A5E32221386-AC
10.4
Operation troubleshooting
Operating symptoms, probable causes, and resolutions.
Symptom
Cause
Action
Display shows
level or target is out of range
• check specifications
• check
Low Calibration Pt. (1.6.)
• increase
Confidence (2.5.9.1.)
Display shows
material build-up on antenna
• clean the antenna
• re-locate SITRANS LR250
Display shows
location or aiming:
• poor installation
• flange not level
• Auto False Echo Suppression
may be incorrectly applied
• check to ensure nozzle is vertical
• ensure end of antenna protrudes from end of nozzle
• review Auto False Echo Suppression (Page 236)
• ensure Auto False Echo Suppression Range is set
correctly
Display shows
antenna malfunction:
• temperature too high
• physical damage
• excessive foam
• multiple echoes
• check temperature in
Maximum Value (3.3.2.)
• use foam deflector or stillpipe
• relocate
• use a defoamer
• set
Algorithm (2.5.7.1.)
to t
F
(trueFirst echo)
Reading does not
change, but the level
does
SITRANS LR250 processing
wrong echo, for example, vessel
wall, or structural member
• 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 236)
Measurement is
consistently off by a
constant amount
• setting for
Low Calibration
Point (2.3.7.1.)
not correct
• setting for
Sensor Offset
(2.3.7.3.)
not correct
• check distance from sensor reference point to
Low
Calibration Point (2.3.7.1.)
• check
Sensor Offset (2.3.7.3.)
Screen blank power error
• check nameplate rating against voltage supply
• check power wiring or source
too much load resistance
• change barrier type, or
• remove something from the loop, or
• increase supply voltage
• reduce wire distance or use larger gage wire

Siemens Sitrans LR250 Specifications

General

Accuracy	± 2 mm
Power Supply	10.5 to 42 V DC
Measurement Principle	Radar
Process Temperature	-40 to +80 °C
Process Pressure	Up to 40 bar
Output Signal	4 to 20 mA HART
Communication	HART
Enclosure Rating	IP68
Housing Material	Aluminum, stainless steel