Using the concepts of typical gas’s concentration and cumulative frequency in analysis of the reliability data for dealing with the pretreatment of data of dissolved gas analysis（DGA）

two new normalized methods which named characteristic normalization and mix normalization were presented in this paper.The Fisher rule to evaluate the results of the two pretreatment methods was also introduced.The evaluation of the results indicated that both of the two data pretreatment methods could achieve the purpose of big difference in the value of mean between classes and small difference in dispersion of a class.The DGA data of the failure transformers were treated by different normalization methods as the training samples

and then the samples were trained in the compound neural networks which use the CP algorithm.The diagnosis results of the test samples indicated that the new methods may help to improve the precision of network diagnosis.