Evaluation of porcelain and toughened glass suspension insulators removed from service

A. P. Mishra, R. S. Gorur, S. Venkataraman

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Porcelain and toughened glass suspension type insulators that were removed after 25-30 years of service were evaluated in the laboratory with the objectives of understanding failure mechanisms and assessing the condition of similar insulators in the field. The remaining electrical and mechanical strength was highly variable for porcelain and for some they were significantly reduced from the rated value. Scanning electron microscopy and electric field calculations provided an insight into the failure mechanism responsible for electrical strength reduction in porcelain. Toughened glass insulators with shells shattered intentionally in the laboratory (stubs) always flashed over externally and were therefore puncture proof. Multiple explanations are provided to explain this phenomenon based on internal examination of the stubs. The variation in the tensile load to cause failure for toughened glass insulators was smaller when compared to porcelain and was close to the rated value.

Original languageEnglish (US)
Article number4483466
Pages (from-to)467-475
Number of pages9
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Issue number2
StatePublished - Apr 2008


  • Aging
  • Condition assessment
  • Failure mechanisms
  • Glass insulators
  • Porcelain insulators
  • Puncture
  • Residual strength
  • Tensile strength

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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