LEFM 3xxCi User Manual
IB1406 Rev 12
Section 6
Page 40
August 2017
Display 1—Main Display Data
Figure 6.2 Display 1 – Main Display Data
Alarm Conditions
The LEFM 3xxCi’s automatic fault detection system is specially designed to verify the performance of the
transducers and transmitter electronics and to alert personnel when abnormal operating conditions are
detected.
It detects faults in three basic steps:
1.
The system checks the data quality for ultrasonic paths and evaluates the data against thresholds.
Data evaluation is based on signal to noise ratio (SNR), cross-correlation tests, and signal statistics.
2.
The transmitter confirms the self-consistency of the sound velocities computed by each path.
3.
The transmitter confirms the velocity profile parameters. The parameters are FR (Flatness Ratio),
Swirl, Plane Balance (relative results of the two planes of the flowmeter), and AR (Asymmetry Ratio or
the balance between the top of the meter and the bottom of the meter).
The transmitter outputs the current status via the Ethernet port, serial port, and digital outputs. The
displayed status may be any of the following:
•
NORMAL
•
F-PATH Failed paths (flow is computed with a possibility of lesser accuracy)
•
F-VOS
Failed Sound Velocity (path sound velocity spread is out of range)
•
F-PROFILE
Failed Profile (one or more of the velocity profile tests out of range)
Note – 1, 2, 3, 4, or 5 path failures lose no accuracy for custody transfer applications when operating
conditions do not change significantly.
Flow rate units:
Cubic meters/hour –M3/H
Cubic meters/second – M3/S
Cubic feet/sec – CFS
