Improved technique for fault detection sensitivity in transformer impulse test

Evaluation of Lightning Impulse Test by Frequency Response Analysis

“…Because the most common measurements acquired during impulse testing are applied voltage and neutral current the transfer function analyzed is the impedance of the winding under test with all other connections to ground. Even so another transfer functions as transferred voltage between adjacent windings may be more sensitive to some types of faults [25].…”

Application of wavelets to identify faults during impulse tests

“…Several studies on the application of wavelet analysis to identify faults during transformer im-0-7803-9257-4/05/$20.00 @2005 IEEE High Voltage Test Set-up pulse tests have been published [2][3][4]. In [3], the authors have proposed the use of multiresolution signal decomposition to detect the fault current embedded into the neutral current.…”

“…In [4], wavelet transformation has been used to find the power spectral density of actual test waveforms in their work which were obtained by introducing permanent faults in a single phase transformer 1.43kV/240V, 1 kVA. However, in practice, faults during the impulse testing are more likely of the temporary variety which last a few micro seconds.…”

“…There have been several studies [2][3][4] on the application of wavelets to identify faults during high voltage impulse testing. Most of these studies have utilized simulated waveforms in which the fault is introduced by a suitable mathematical model.…”

Partial discharge propagation studies in generator and transformer

“…-+ --= 0 (20) dx 2 dt dx 2 dt 2 dt 2 dt dx 2 To solve (20), substitute d/dt = p. (20) reduces to (21) rKp^ + LKp 2^-LCp 2 -rCp + ^r = 0 (21)…”