Detection of internal incipient faults in transformers during impulse test using hyperbolic S-transform

SUMMARY In this paper, the application of the hyperbolic S‐transform is proposed for detecting internal incipient faults of transformers during the impulse test. This test is performed on the under consideration transformer and during this test, the input current and applied voltage are recorded. The S‐transform is applied to the recorded input current. An index is proposed and computed considering absolute deviations of the S‐matrix. Faulty and non‐faulty windings are discriminated by using the suggested index. The data obtained from field tests of a 66 kV/25MVA interleaved transformer winding and computer simulations, are recorded. Then, these data are fed to the proposed method, and faulty and normal conditions are discriminated, accordingly. Also, a wavelet‐based method is implemented in MATLAB environment and the proposed method is compared with the wavelet‐based method. According to simulations and experimental results, the proposed method is superior to wavelet transform‐based method. Copyright © 2012 John Wiley & Sons, Ltd.