Common TOA4 Import Problems

When you are trying to import test data into your TOA4 Online account, there can be various reasons why either TOA4 refuses to accept the data file or some of the data records don’t get imported. Here are some cases that users have encountered so far: File upload fails 1. Error parsing data file. Usually, this means that you have clicked the wrong thing and tried to upload a spreadsheet (.xls) or word processing (.doc) file. Sometimes it means that the file has been corrupted and contains non-text gibberish. Import operation fails 1. Missing or mis-named required columns. For example, if the apparatus type (apprtype) column is not found, neither equipment nor test data can be imported. Often it turns out that the column is not missing, but its name is spelled wrong. 2. Missing sampledate c ...

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Thermodynamic Estimation of Transformer Fault Severity

Authors:  F. Jakob and J.J. Dukarm Published in Power Delivery, IEEE Transactions vol.30, no.4, pp.1941-1948, Aug. 2015 doi: 10.1109/TPWRD.2015.2415767 Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring r ...

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Remember in TOA4 Online to Analyze New Data

When you import new test data in TOA4, the dialog that appears just after you click “Import test data” contains a checkbox that tells TOA4 to do an analysis immediately upon completing the import. Normally, this checkbox should be left “checked” unless you are importing many thousands of samples at once. Really huge import files should be broken up into smaller ones anyway. If you do import new test data without doing an analysis, an “Analyze new” button should be displayed below the equipment list. Be sure to click that button to calculate analysis results before starting to review UNREVIEWED data. After all new data records have been analyzed, the “Analyze new” button is no longer displayed. Note that if the equipment “owning” the data does not have a correct norm name associated with it ...

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Cluster Assessment for Online DGA Monitoring

Author James J. Dukarm 2015 CIGRE Canada Conference This paper describes a cluster assessment (CA) method for automatic detection, assessment, and logging of significant fault gas production events by enalysis of multi-gas online monitor data. When large numbers of transformers are monitored, automatic screening interpretation of the data is necessary. The automated interpretation of dissolved gas data must be quite skilled at discriminating between exceptional and unexceptional patterns to provide high sensitivity and high specificity, i.e., to detect incipient problems reliably while generating very few false alarms. The CA method is applied to a moving time window of the most recent 30 to 90 days of multi-gas monitor data for each transformer. It relies upon three innovative elements: P ...

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A Thermodynamic Approach to Evaluation of the Severity of Transformer Faults

Authors: F. Jakob, P. Noble, J.J. Dukarm, Published in Power Delivery, IEEE Transactions on vol.27, no.2, pp.554-559, April 2012 doi: 10.1109/TPWRD.2011.2175950 Abstract: Dissolved gas analysis (DGA) has been used to classify the type and severity of faults in transformers. The method commonly used to identify severity is to measure the total fault gas concentration and its rate of change, without regard to the relative concentrations of individual gases. Thermodynamic analysis indicates that the energy required to form gases increases in the order CH4 <; C2H6 ≤ CO ≤ C2H4 <; H2 ≪ C2H2. Based on these results, an energy-weighted dissolved gas analysis (EWDGA) is proposed, where concentrations of individual gases are multiplied by a weighting factor that is proportional to the energy r ...

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