Insulation thermal life considerations for transformer loading guides

The author offers recommendations for a new treatment of insulation thermal life which recognizes the effects of more significant parameters and would enable users to make more realistic judgements about the impact of loading on functional life. Background tutorial material from the published literature is presented as an aid to understanding the basis for the change. In the proposed method of treatment of insulation life in loading guides, a single aging rate constant would be used for all distribution and power transformers to calculate life consumption during any given loading condition relative to continuous operation at a reference temperature. The definition of absolute 'insulation life' would be influenced by the moisture and oxygen content of the insulation system and the life end-point criterion selected. >

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