Novel technique to improve the fault detection sensitivity in transformer impulse test

Essam Al-Ammar, George G. Karady, H. Jim Sim

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Insulation is identified as one of the most important constructional rudiments of a transformer, and any weakness of insulation would lead to a transformer failure. To check the insulation integrity, a sensitive technique like the standard impulse test is used. Testing of winding insulation is performed by comparing the voltage and current waveforms of reduced and full test voltages, previously. Transfer function has been exercised via applying fast Fourier transform to analyze the transformer state in the frequency domain. In order to enhance the fault detection sensitivity in transformer impulse test, this paper proposes a new method using short time Fourier transform in the transfer function analysis, derived from experimental works on 25 kVA and 26 MVA transformers. It is concluded that the fault detection sensitivity is improved significantly by using STFT analysis, including minor faults.

Original languageEnglish (US)
Pages (from-to)717-725
Number of pages9
JournalIEEE Transactions on Power Delivery
Issue number2
StatePublished - Apr 2008


  • Faults
  • Signature analysis
  • Time-frequency representation
  • Transformer

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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