LEFM 3xxCi User Manual
IB1406 Rev 12
Section 8
Page 61
February 2017
2.
Verify continuity of all cable connections.
3.
Check the display. If the display reports “Configuration File Needed” or “Flowmeters”, the transmitter
needs to be reprogrammed or the CTC board requires replacement. Refer to Section 8,
Reprogramming the Transmitter.
4.
Check the acoustic signal. Check path gains via Modbus or LEFMLink software. If the path gains are
high (65 dB or higher), the signals may be too weak to be detected. Weak signals can be caused by
any of the following (listed from most likely to least likely):
•
The line contains liquid.
•
The line pressure is too low.
•
The cable/wire from the meter to the transmitter is damaged.
•
The transducer coupling needs to be replaced (with grease couplants only).
•
The transducer has failed.
5.
Review the SNR for each path (paths 1 through 8).
6.
Review the gains for each acoustic path (both upstream and downstream). The gains are typically
between 20 dB and 70 dB. Gain is dependent on pressure, composition, velocity, and temperature. It
will vary as conditions change. Upstream and downstream gain should nominally be within 12 dB of
each other.
7.
Review the performance data for each path. The percent accepted data should be between 95 and
100%.
Remember the following troubleshooting tips:
o
If all paths fail, the meter has low pressure, significant liquid, or an electronics hardware failure has
occurred.
o
If a path has 0% accepted valid data, the transmitter cannot lock onto a signal. The cables or
transducers should be investigated for potential failure.
o
If an acoustic signal does not exist, or if SNR has degraded from installation, follow the checklist
below:
1.
Verify the pipe contains no liquid.
2.
Check the continuity of transducer cable in the manifold.
3.
If a signal is present, consider reseating the ultrasonic transducer or replacing the acoustic
coupling. Refer to Section 7, Maintenance.
