Sensor Troubleshooting - Emerson Rosemount 8732EM Reference Manual

Troubleshooting
Table 12-7: Common Magmeter Issue
Symptom
Meter output is unstable Medium to low conductivity fluids
12.6

Sensor troubleshooting

This section describes manual tests that can be performed on the sensor to verify the
health of individual components. The tests will require the use of a digital multimeter
capable of measuring conductance in nanoSiemens and an LCR meter. A sensor circuit
diagram is shown in
isolation of the internal components of the sensor.
170
(continued)
Potential cause
(10–25 microsiemens/cm) combined
with cable vibration or 60 Hz interfer-
ence
Electrode incompatibility
Improper grounding
High local magnetic or electric fields
Control loop improperly tuned
Sticky valve (look for periodic oscilla-
tion of meter output)
Sensor failure
Analog output loop problem
Figure 12-1. The tests described below will check for continuity or
Rosemount
Corrective action
Eliminate cable vibration
Move cable to lower vibration run
Tie down cable mechanically
Use an integral mount
Trim electrode and coil wires - see
Route cable line away from other equipment pow-
ered by 60 Hz
Use component cable - see
Check the Technical Data Sheet, Magnetic Flowme-
ter Material Selection Guide (document number
00816-0100-3033), for chemical compatibility with
electrode material
Check ground wiring – see
grounding procedures
Move magnetic flowmeter (20–25 ft away is usually
acceptable)
Check control loop tuning
Service valve
Perform the sensor tests (See
Check that the 4 to 20 mA loop matches the digital
value Perform analog output test
®
8732EM Transmitter with HART Protocol Reference Manual
Section 4.4.3
Section 4.4.3
Section 3.4 for wiring and
Section 12.7)