Uninstalled Sensor Tests - Emerson Rosemount 8782 Reference Manual

Troubleshooting
November 2019
Table 12-11: Test D. Electrode to electrode shield
Test conditions
• Location: installed
• Required equipment: LCR
(Set to Resistance and 120
Hz)
• Measuring at connections:
— 18 and 17 = R
1
— 19 and 17 = R
2
Table 12-12: Test E. Electrode to Electrode
Test conditions
• Location: installed
• Required equipment: LCR
(Set to Resistance and 120
Hz)
• Measuring at connections:
18 and 19
— 18 and 17 = R
1
— 19 and 17 = R
2
To test the sensor, a multimeter capable of measuring conductance in nanoSiemens is
preferred. Conductance is the reciprocal of resistance.
Or:
12.8

Uninstalled sensor tests

Sensor troubleshooting can also be performed on an uninstalled sensor. If test results from
installed sensor tests are inconclusive, the next step is remove the sensor and perform the
tests outlined in this section. Take measurements from the recommended terminal
location, and directly on the electrode head inside the sensor. The measurement
144
Expected Potential cause
value
• R and R • Unstable R
1 2
should be confirm coated electrode
stable
• Shorted electrode
• |R –R |
1 2
• Electrode not in contact with
≤300Ω
process
• Empty pipe
• Low conductivity
• Leaky electrode
• Process reference ground
not connected properly
Expected Potential cause
value
Should be • Unstable R
stable and confirm coated electrode
same relative
• Shorted electrode
magnitude of
R and R from
• Electrode not in contact with
1 2
Test D
process
• Empty pipe
• Low conductivity
• Leaky electrode
• Process reference ground
not connected properly
®
Rosemount 8782 Slurry Magnetic Flow Meter Transmitter with HART Protocol
Corrective action
or R values • Remove coating from sensor
1 2
wall
• Use bullet-nose electrodes
• Repeat measurement
• Remove sensor and
complete tests in
sensor tests
• Connect process reference
ground per
connection
Corrective action
or R values • Remove coating from sensor
1 2
wall
• Use bullet-nose electrodes
• Repeat measurement
• Remove sensor and
complete tests in
sensor tests
• Connect process reference
ground per
connection
Reference Manual
00809-0100-8782
Uninstalled
Process reference
Uninstalled
Process reference