Effect of cumulative moisture content on degradation of transformer paper insulation

Mohamadreza Ariannik, A.A. Razi-Kazemi, M. Lehtonen

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Nowadays, reliability of power system is of great importance. Therefore, the condition of transformers as the expensive and critical components of a power system should be monitored and assessed. The dominant factor that causes limitation in transformers lifetime is the paper insulation. This paper aims to investigate the conspicuous influence of moisture content, especially in low oxygen and temperature on lifetime estimation under constant conditions, based on the results of previous experiments. Degree of polymerization (DP) is employed to quantify the effects of detrimental parameters with respect to their time-varying nature. This paper proposes a novel lifetime estimation-approach considering a yearly moisture growth for transformers. The results indicate different trend of DP profiles, which lead to an accurate lifetime estimation in comparison with DP obtained through ideal conditions. Furthermore, oscillations in the hot-spot temperature of transformers are demonstrated to have a negative effect on the lifetime.
Original languageEnglish
Pages (from-to)611-618
Number of pages8
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Issue number1
Publication statusPublished - 7 Mar 2017


  • transformer
  • paper
  • mositure
  • lifetime estimation
  • degree of polymerization (DP)


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