194 FLOWSIC600 · Technical Information · 8010125 V 4.0 · © SICK AG
Troubleshooting
Subject to change without notice
Interpretation of active User Warning status (continued)
Yellow light
for...
Possible causes Actions
AGC deviation
(signal
amplification)
The difference between the two ultrasonic
transducers on each of the measuring paths is
small, although it can increase at higher
velocities.
If the AGCs of a path deviate more than allowed,
this can indicate a malfunction in the ultrasonic
transducers, electronic modules, transducer
cables or parameter settings (signal models,
control limits).
Check, whether the difference in gain is
increased by a high flow velocity.
Compare the current value with previous
measurements (e.g. Maintenance Report
from commissioning) and check whether the
User Warning limit is configured correctly
(
pg. 149, 5.7.1).
Create a Diagnosis Session according to
pg. 198, 7.3 and contact your trained staff.
SOS deviation
1
The SOS deviation indicates whether or not a
path is measuring the correct transit time.
The measured speed of sound should be stable.
Sudden changes in the measured value may be
indicative of signal detection problems (which
can affect transit time measurements) or
changes in the gas composition. The speed of
sound in the individual paths should also be
approximately identical (see graph on
pg. 171,
Figure 80).
Check, whether a low flow rate may be
causing temperature stratification.
Use the SOS Calculator, to calculate the
theoretical SOS (
pg. 169, 6.2.1).
Compare the current value with previous
measurements (e.g. Maintenance Report
from commissioning) and check whether the
User Warning limit is configured correctly
(
pg. 149, 5.7.1).
Create a Diagnosis Session according to
pg. 198, 7.3 and contact your trained staff.
Performance
limit
The performance is the percentage of valid
received ultrasonic signals for each path. That
means, if 5 of 100 transmitted signals do not
meet the acceptance criteria for a signal
analysis, then the performance of this path is
only 95%. The performance of each path should
be very close to 100% (check on the "Meter
Values" page
pg. 171, Figure 80).
Due to signal attenuation on the way from the
transmitting to the receiving sensor or due to
acoustic noise, also caused by very high gas
velocity, the performance can be significantly
lower. The minimum performance at which
reliable gas velocity values are supplied is 5%.
When the performance falls below 5%, the path
fails and will be substituted by a replacement
value (more details
pg. 28, 2.4).
Significant discrepancies in the values under
comparable conditions (pressure, temperature,
flow velocity, gas composition) indicate that
changes have occurred in the device or piping
(e.g. disturbance caused by a valve that is not
fully open).
A change in performance at comparable
process conditions can indicate a potential
transducer problem (e.g. contamination). A
visual inspection of the ultrasonic signals and
the transducer itself is required.
Create a Diagnosis Session according to
pg. 198, 7.3 and contact your trained staff.
1
These User Warning limits are only monitored, as long as certain preconditions are met (
pg. 154, Table 22).
To Next Page
Loading...
Need help?
General
