5-3
Troubleshooting
ADVANCEDTRANSMITTER
TROUBLESHOOTING
TABLE 5-2. Advanced Troubleshooting–Model 8712C/U/H
Symptom Potential Cause Corrective Action
Does not appear to be within
rated accuracy
Transmitter, control system, or other
receiving device not configured properly
Check all configuration variables for the transmitter, flowtube,
communicator, and/or control system – see Review on page 4-15
Check these other transmitter settings:
• Flowtube calibration number
•Units
• Line size
Perform a loop test to check the integrity if the circuit – see Analog
Output Test on page 5-5
Electrode Coating Use replaceable electrodes in Model 8705;
Downsize flowtube to increase flow rate above 3 ft/s;
Periodically clean flowtube
Air in line Move the flowtube to another location in the process line to ensure
that it is full under all conditions.
Moisture problem Perform the flowtube Tests A, B, C, and D on Table 5-3 on page 5-6.
Improper wiring If electrode shield and signal wires are switched, flow indication will
be about half of what is expected. Check wiring diagrams for your
application.
Flow rate is below 1 ft/s
(specification issue)
See accuracy specification for specific transmitter and flowtube
Auto zero was not performed when the
coil drive frequency was changed from 6
Hz to 30 Hz
Perform the auto zero function – see Auto Zero Trim on page 4-5
Flowtube failure–Shorted electrode Perform the flowtube Tests C and D on Table 5-3 on page 5-6.
Flowtube failure–Shorted or open coil Perform the flowtube Tests A and B on Table 5-3 on page 5-6.
Transmitter failure Replace the electronics boards – see Replacing the
Electronics Module on page 5-7
Noisy Process Chemical additives upstream of
magnetic flowmeter
Complete the Noisy Process Basic procedure (page 5-7).
Move injection point downstream of magnetic flowmeter, or move
magnetic flowmeter.
Sludge flows–Mining/Coal/
Sand/Slurries (other slurries with
hard particles)
Decrease flow rate below 10 ft/s
Styrofoam or other insulating particles
in process
Complete the Noisy Process Basic procedure (page 5-7);
Consult factory
Electrode coating Use replaceable electrodes in Model 8705.
Use a smaller flowtube to increase flow rate above 3 ft/s.
Periodically clean flowtube.
Air in line Move the flowtube to another location in the process line to ensure
that it is full under all conditions.
Low conductivity fluids (below 10
micromhos/cm)
Trim electrode and coil wires – see Conduit Cables on page 2-7
Advanced Troubleshooting continued on next page
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