Emerson MMI-20019043 Manuel D’Utilisation
12.5
Temperature measurement problems
Temperature measurement problems and recommended actions
Table 12-5:
Problem
Possible causes
Recommended actions
Temperature reading
significantly different
from process temper-
ature
significantly different
from process temper-
ature
•
RTD failure
•
Wiring problem
•
Check junction box for moisture or verdi-
gris.
gris.
•
Perform RTD resistance checks and check
for shorts to case (see
for shorts to case (see
).
•
Confirm the temperature calibration factor
matches the value on the sensor tag.
matches the value on the sensor tag.
•
Refer to status alarms (especially RTD fail-
ure alarms).
ure alarms).
•
Disable external temperature compensa-
tion.
tion.
•
Verify temperature calibration.
•
Check the wiring between the sensor and
transmitter. See
transmitter. See
.
Temperature reading
slightly different from
process temperature
slightly different from
process temperature
•
Sensor temperature not yet equalized
•
Sensor leaking heat
•
The RTD has a specification of ±1 °C. If the
error is within this range there is no prob-
lem. If the temperature measurement is
outside the specification for the sensor,
contact Micro Motion.
error is within this range there is no prob-
lem. If the temperature measurement is
outside the specification for the sensor,
contact Micro Motion.
•
The temperature of the fluid may be
changing rapidly. Allow sufficient time for
the sensor to equalize with the process flu-
id.
changing rapidly. Allow sufficient time for
the sensor to equalize with the process flu-
id.
•
Insulate the sensor if necessary.
•
Perform RTD resistance checks and check
for shorts to case (see
for shorts to case (see
).
•
The RTD may not be making good contact
with the sensor. The sensor may need to
be replaced.
with the sensor. The sensor may need to
be replaced.
Troubleshooting
Configuration and Use Manual
223