Add to ORKGA modern electric power system is a very large and complex network consisting of generators, power transformers, transmission lines, distribution lines, and other devices. Power transformer is one of the most important electricity equipment in power system. It plays important roles both in transmission and in distribution system. Power transformer condition should be maintained because of its importance in electricity network. There is an increasing need for better diagnostic and monitoring tools to assess the condition of transformers. Many monitoring, testing and condition assessment techniques have been used. By means of statistical failure analysis, the ageing processes related to the ages of the transformer can be shown. The failure da...