Siemens Probe-LU Ultrasonic Level Transmitter

Mounting tips
Siemens Probe-LU Ultrasonic Level Transmitter
1. If mounting on a pipe nozzle, the nozzle length should be no longer than twice the
diameter. Example: 6” ID nozzle should be 12” long maximum.
The following tips will prevent sensor ‘Ringback’. This is the vibration feedback
from the vessel or conduit back to the sensor.
2. If threaded mount sensor, do not screw in too tight.
Other troubleshooting parameters to check
P805, Echo Confidence. Displays the echo confidence of the measurement echo from the last
shot. First number is echo confidence in near zone (within 3’ of sensor), Second number is
confidence in far zone (distance further than 3’ from sensor face). If material is further than 3’
from sensor face, and have any number other than ‘0’ in near zone, sensor may be getting false
echo due to nozzle, ringback (see above).
P806, Echo Strength. Displays the strength (in dB above 1 uV RMS) of the echo which was
selected as the measurement echo.
P807, Noise. The noise level is a combination of transient acoustic noise and electrical noise
(induced into the transducer cable or receiving circuitry). Primarily caused by sensor cable in
near proximity to high power cable, or nearly VFDs. See Noise Problems in the Troubleshooting
Section

Common Problems Chart
Note: Many of the parameters and techniques described here require extensive knowledge of ultrasonic
technologies and Siemens echo processing software. Use this information with caution.
Sym
Symptom Cause Action
Display blank, transducer
not pulsing.
No response to programmer.
No power.
Obstructed infrared interface,
defective programmer.
Check power supply, wiring, or
power fuse.
Check programmer usage:
15 cm (6”) from faceplate
pointed at upper target.
Displays LOE. Weak or non-existent echo. Relocate and/or re-aim transducer
at material.
Proceed to Measurement difficulties.
Reading is fixed, regardless of the
actual material level.
Material level reported is always
incorrect by the same amount.
Reading is erratic, with little or no
relation to material level.
Transducer acoustic beam
obstructed, standpipe too narrow,
or transducer ringing (reads over
100%).
Incorrect Empty (zero) reference
for level operation (P001= 1).
True echo too weak or wrong echo
being processed.
Relocate and / or re-aim transducer
at material level or object.
Proceed to Measurement Difficulties
below. See also: Transducer ringing.
See Empty (P006), Reading Offset
(P063), Offset Calibration (P650), &
Offset Correction (P652).
Relocate and / or re-aim transducer
at material.
Check noise parameters. See Noise
Problems.