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Meters Measurement Comparison Between Cases

This analysis rule indicates the in-service mass/volume measurement elements with a change of value between Cases that is greater than the configured delta limit. The limit is in percent of value and in engineering units. A limit of zero means that the limit has not been configured. The limit must be greater then zero for the limit to be used.

Any in-service meter measurement with a value change greater than the configured limit is reported to the Case log, which you can view in the Log tab of the Case Properties window. The output contains a list of meters in violation, and a description of the violation.

The following table lists a sample log output for this analysis.

Sample Log

TimeSeverityElementAttributeMessage
9/25/2005 13:22...REPORTING METER MEASUREMENT COMPARISON BETWEEN CASES - BASIS= MASS
9/25/2005 13:22WarningMeterACurrent Case MeasuredMass: 50 (kg), Previous Case MeasuredMass:1 (kg), Diff: 49, %Diff: 98
9/25/2005 13:22WarningMeterBCurrent Case CorrectedMass: 1 (kg), Previous Case MeasuredMass:0 (kg), Diff: 1, %Diff: 100

Analysis Method​

  1. Collect a list of all the in-service meter elements in the current case. Collect a list of all the in-service meter elements from the previous period.

  2. Determine the meter elements with a change in measured value greater than the limit specified. If the flag for a correction is set (equals 1), then the value in the corrected value Attribute is used. The following method is used:

    If abs( previous value – current value ) > absolute threshold

    OR

    abs( previous value – current value )/current value*100 > percent threshold.

  3. Write to the log section of the case. Report the test name and the Measurement Basis. Report the list of offending meters, ordered by name and cause of violation.

Configuration Using the Wizard​

The configuration of the Meters measurement comparison between cases is a selection of the General Gross Error Analysis Rule. You open the window for configuring the test (shown in the following figure) from the General Gross Error Analysis Rule Wizard.

  1. Open the Gross Error Configuration window as described in Configuring - General Gross Error Analysis Rule.

  2. On the Liquid/Gas Meters tab, select Meters measurement comparison between cases.

    A Meters measurement comparison between cases - Attributes window opens.Figure 395: Meters measurement comparison between cases - Attributes window

  3. Select the measurement basis and the Attributes according to the following table:

    Attributes

    SelectionsDescription
    Measurement BasisSelect mass or volume basis.
    MeasuredMeter actual measurement. This defaults to 'MeasuredMass' or 'MeasuredVolume' depending on mass or volume selection.
    CorrectedMeter corrected measurement. This defaults to 'CorrectedMass' or 'CorrectedVolume' depending on mass or volume selection.
    Manual FlagFlag to indicate if a corrected measurement was used for the meter. This defaults to 'ManualAdjustmentFlag',
    DifferenceEnter a value in the engineering unit of the Measured attribute.
    Percent DifferenceEnter a value in percent.
    StatusMeter in/out of service status. This defaults to 'ObjectStatus'.

  4. Enter the Difference and Percentage Difference thresholds.

  5. Click OK to finish the configuration.

    The text "CONFIGURED" displays next to the 'Meters measurement comparison between cases' selection.

  6. To run this test, see Running the General Gross Error Analysis.