Emerson Rosemount 8782 - Uninstalled Sensor Tests

Table 12-11: Test D. Electrode to electrode shield
Test conditions Expected
value
Potential cause Corrective action
• Location: installed
• Required equipment: LCR
(Set to Resistance and 120
Hz)
• Measuring at connections:
— 18 and 17 = R
1
— 19 and 17 = R
2
• R
1
and R
2
should be
stable
• |R
1
–R
2
|
≤300Ω
• Unstable R
1
or R
2
values
confirm coated electrode
• Shorted electrode
• Electrode not in contact with
process
• Empty pipe
• Low conductivity
• Leaky electrode
• Process reference ground
not connected properly
• Remove coating from sensor
wall
• Use bullet-nose electrodes
• Repeat measurement
• Remove sensor and
complete tests in Uninstalled
sensor tests
• Connect process reference
ground per Process reference
connection
Table 12-12: Test E. Electrode to Electrode
Test conditions Expected
value
Potential cause Corrective action
• 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
Should be
stable and
same relative
magnitude of
R
1
and R
2
from
Test D
• Unstable R
1
or R
2
values
confirm coated electrode
• Shorted electrode
• Electrode not in contact with
process
• Empty pipe
• Low conductivity
• Leaky electrode
• Process reference ground
not connected properly
• Remove coating from sensor
wall
• Use bullet-nose electrodes
• Repeat measurement
• Remove sensor and
complete tests in Uninstalled
sensor tests
• Connect process reference
ground per Process reference
connection
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
Troubleshooting Reference Manual
November 2019 00809-0100-8782
144 Rosemount
®
8782 Slurry Magnetic Flow Meter Transmitter with HART Protocol