Measurement Troubleshooting - Emerson Rosemount 3051SMV MultiVariable Reference Manual

Troubleshooting
January 2019
5.3

Measurement troubleshooting

The transmitter provides a means to display the current process variables and flow
calculations. If the process variable reading is unexpected, this section provides the
symptoms and possible corrective actions.
Table 5-1: Unexpected Process Variable (PV) Readings
Symptom
High PV
Reading,
Erratic PV
Reading, Low
or no PV
reading
5.3.1 Fill fluid
The following performance limitations may inhibit efficient or safe operation. Critical
applications should have appropriate diagnostic and backup systems in place.
Pressure transmitters contain an internal fill fluid. It is used to transmit the process
pressure through the isolating diaphragms to the pressure sensor module. In rare cases, oil
loss paths in oil-filled pressure transmitters can be created. Possible causes include:
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Corrective action
Primary element
• Check for restrictions at the primary element.
• Check the installation and condition of the primary element.
• Note any changes in process fluid properties that may affect output.
Impulse piping
• Check to ensure the pressure connection is correct.
• Check for leaks or blockage.
• Check to ensure that blocking valves are fully open.
• Check for entrapped gas in liquid lines or for liquid in gas lines.
• Check to ensure the density of fluid in impulse lines is unchanged.
• Check for sediment in the transmitter process flange.
• Make sure that process fluid has not frozen within the process flange.
Power supply
• Check the output voltage of the power supply at the transmitter. It should be
9 to 30 V dc (9 to 17.5 V dc for FISCO)
Flow configuration (fully compensated mass flow feature board only)
• Verify flow configuration is correct for current application
Process temperature RTD input
• Verify the PT Mode (Normal, Fixed, Back-up)
• Verify the correct Callendar-Van Dusen coefficients
• Verify all wire terminations
• Verify sensor is a Pt 100 RTD
• Replace Pt 100 sensor
Sensor module
• Check for obvious defects, such as a punctured isolating diaphragm or fill fluid
loss, and if replacement is needed, contact the nearest Emerson Service
Center.
• Check for proper fill fluid characteristics (see
Reference Manual
00809-0100-4853
Fill fluid for more information).
Reference Manual