Emerson Process Management 8732 manual 8714I Meter Verification, Sensor Signature Parameters

Rosemount 8732

Reference Manual

00809-0100-4663, Rev BA January 2010

8714I METER VERIFICATION

Sensor Signature Parameters

The transmitter continuously monitors signal amplitudes over a wide range of frequencies. For the high process noise diagnostic, the transmitter specifically looks at the signal amplitude at frequencies of 2.5 Hz, 7.5 Hz, 32.5 Hz, and

42.5Hz. The transmitter uses the values from 2.5 and 7.5 Hz and calculates an average noise level. This average is compared to the amplitude of the signal at 5 Hz. If the signal amplitude is not 25 times greater than the noise level, and the coil drive frequency is set at 5 Hz, the High Process Noise alert will activate indicating that the flow signal may be compromised. The transmitter performs the same analysis around the 37.5 Hz coil drive frequency using the 32.5 Hz and 42.5 Hz values to establish a noise level.

The 8714i Meter Verification diagnostic provides a means of verifying the flowmeter is within calibration without removing the sensor from the process. This is a manually initiated diagnostic test that provides a review of the transmitter and sensors critical parameters as a means to document verification of calibration. The results of running this diagnostic provide the deviation amount from expected values and a pass/fail summary against user-defined criteria for the application and conditions.

Initiating 8714i Meter Verification

375Transducer Block, Diagnostics, Advanced Diagnostics, 8714i Meter Verification AMS Tab Diagnostics

The 8714i Meter Verification diagnostic can be initiated as required by the application. If the advanced diagnostic suite (D02) was ordered, then the 8714i Meter Verification diagnostic will be available. If D02 was not ordered or licensed, this diagnostic will not be available.

The sensor signature describes the magnetic behavior of the sensor. Based on Faraday’s law, the induced voltage measured on the electrodes is proportional to the magnetic field strength. Thus, any changes in the magnetic field will result in a calibration shift of the sensor.

Establishing the baseline sensor signature

The first step in running the 8714i Meter Verification test is establishing the reference signature that the test will use as the baseline for comparison. This is accomplished by having the transmitter take a signature of the sensor.

375Transducer Block, Diagnostics, Advanced Diagnostics, 8714i Meter Verification, Sensor Signature, Re-Signature

AMS Tab Context Menu, Diagnostics and Tests,

Having the transmitter take an initial sensor signature when first installed will provide the baseline for the verification tests that are done in the future. The sensor signature should be taken during the start-up process when the transmitter is first connected to the sensor, with a full line, and ideally with no flow in the line. Running the sensor signature procedure when there is flow in the line is permissible, but this may introduce some noise into the signature measurements. If an empty pipe condition exists, then the sensor signature should only be run for the coils.

Once the sensor signature process is complete, the measurements taken during this procedure are stored in non-volatile memory to prevent loss in the event of a power interruption to the meter.

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