Evaluation method for detection capability of dissolved gas analysis in transformer oil
Four kinds of methods were selected to evaluate the chromatography detection results of gas chromatograph from each company,then the application results of each evaluation methods in the evalua-tion of transformer oil chromatographic detection capability were researched.The result showed that the it-erative robust statistical method combined with the repeatability requirements in GB/T 17623-2017 has higher reliability.The Z-score classical statistical method is stricter than the Z-score robust statistical method,but both of them have the risk of over deleted.It is suggested to set the"dissatisfied"evaluation criteria for both of them as|Z|≥3 and apply them in combination with the repeatability requirement in GB/T 17623-2017.The iterative robust statistical method has a high agreement with the boxplot outlier removal results in the Z-score classical statistical method.Besides,only one gas detection parameter of one instrument is removed by the boxplot outlier but not by the iterative robust statistical method,and other re-moval results are all included in the removal results of the iterative robust statistical method.The result showed that the iterative robust statistical method has high credibility in removing outliers,and the boxplot can be used directly to remove outliers for evaluation when the Z-score classical statistical method is ap-plied.
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