Emerson Rosemount 3095, Справочное руководство, Страница: 113 / 130

Reference Manual
00809-0100-4716, Rev JA
May 2008
5-7
Rosemount 3095 MultiVariable
Erratic PV Reading DIFFERENTIAL PRODUCER
• Check the installation and condition of the differential producer.
LOOP WIRING
• Check for adequate voltage to the transmitter. It should be 11 to 55 V dc for HART (9 to 32 V dc for fieldbus) with
no load at the transmitter terminals.
• Check for intermittent shorts, open circuits, and multiple grounds.
Note:
Do not use higher than the specified voltage to check the loop, or damage to the transmitter electronics may result
.
PROCESS PULSATION
• Adjust the electronic damping (see page 4-17).
TRANSMITTER ELECTRONICS
• Connect a personal computer and use the EA Software to check the sensor limits to ensure calibration
adjustments are within the sensor range and that calibration is correct for the pressure being applied.
• Connect a personal computer and using the EA Software, select Diagnostics, Error Info
to detect any electronic failures.
• Make sure the post connectors are clean.
• Confirm that the electronics housing is properly sealed against moisture.
• If the electronics are still suspect, substitute new electronics.
IMPULSE PIPING
• Check for entrapped gas in liquid lines and for liquid in gas lines.
• Make sure that process fluid has not frozen within the process flange.
SENSING ELEMENT
• The sensing element is not field repairable and must be replaced if found to be defective. Check for obvious
defects, such as a punctured isolating diaphragm or fill fluid loss, and contact your nearest Rosemount Service
Center.
Low PV Reading or
No PV Reading DIFFERENTIAL PRODUCER
• Check the installation and condition of the differential producer.
• Note any changes in process fluid properties that may affect output.
LOOP WIRING
• Check for adequate voltage to the transmitter. It should be 11 to 55 V dc for HART (9 to 32 V dc for fieldbus) with
no load at the transmitter terminals.
• Check the milliamp rating of the power supply against the total current being drawn for all transmitters being
powered.
• Check for shorts and multiple grounds.
• Check for proper polarity at the signal terminal.
• Check loop impedance.
• Check the wire insulation to detect possible shorts to ground.
Note: Do not use higher than the specified voltage to check the loop, or damage to the transmitter electronics may result .
IMPULSE PIPING
• Check to ensure that the pressure connection is correct.
• Check for leaks or blockage.
• Check to ensure that blocking valves are fully open and that bypass valves are tightly closed.
• Check for entrapped gas in liquid lines and for liquid in gas lines.
• Check for sediment in the transmitter process flange.
• Make sure that process fluid has not frozen within the process flange.
TRANSMITTER ELECTRONICS
• Connect a personal computer and use the EA Software to check the sensor limits to ensure calibration
adjustments are within the sensor range and that calibration is correct for the pressure being applied.
• Connect a personal computer and using the EA Software, select Diagnostics, Error Info
to detect any electronic failures.
• Make sure the post connectors are clean.
• Confirm that the electronics housing is properly sealed against moisture.
• If the electronics are still suspect, substitute new electronics.
SENSING ELEMENT
• The sensing element is not field repairable and must be replaced if found to be defective. Check for obvious
defects, such as a punctured isolating diaphragm or fill fluid loss, and contact your nearest Rosemount Service
Center.
Table 5-6. Unexpected Process Variable (PV) Readings