
Diagnosing and troubleshooting
9.1 Unexpected behavior
SITRANS F Ultrasonic flowmeters FST030 (HART)
86
Operating Instructions, 08/2017, A5E35971532-AC
Symptoms
Diagnostics
Cause
Remedy
Flow not stable
•
Error "Measurement path
error" is pending (menu 2.1)
•
Gain or the active paths > 250
•
Low or no signal return
•
Error counters are not equal
to 0.
Air bubbles or particles
of any kind disturbing
the measurement
Make sure that the pipe line is venti-
lated and that the concentration of
particles is limited to a level at which
normal measurement with the meter
is possible.
Cable partly connected Make sure that the sensor cables
are connected in the transmitter and
in the sensors.
Check the connection of the cable
grounding shield.
Make sure that the shield and cen-
ter pin is connected inside the sen-
sor top.
Ultrasonic echoes
Make sure that the entered path
lengths correspond to the meas-
urement report.
Device displays nega-
tive flow
-
Sensor cables incor-
rectly connected
•
Make sure that the sensor ca-
bles are connected correctly:
–
1A
→
1A
–
1B
→
1B
–
2A
→
2A
–
2B
→
2B
•
Change flow direction
Wrong setting of meas-
urement direction
Make sure that the setting of menu
3.1.5.1 is "+ Direction"
Pulse/frequency out-
put does not work
Error "P/F too high" is pending
(menu 2.1)
Internal electrical failure
(open circuit, short
circuit etc.)
Start simulation on the
pulse/frequency output via menu
2.4. The frequency measuring in-
strument is coupled directly on the
terminals.
Pulse/pause or fre-
quency out of range
Adjust pulse or frequency output
settings (menu 4.2)
Device displays 0
flow.
Device status: "OK"
•
Process flow value
is very low com-
pared with the low
flow cut-off limit of
the device
•
Sensor cables mis-
matched
For testing, check the low flow cut
off (menu 3.1.6) is set to 0.
LCD display dark or
partly dark (missing
characters)
Internal electrical failure
(open circuit, short
circuit etc.)
Turn off power. Check the connec-
tions for the power supply PCBA
and the flat cable for the display
module. Start display test (menu
2.3.2.) in case of partly dark display.