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Mechanical damages in transformer windings during its nascent stages are usually confined to small portions of the winding and can therefore be assumed as localized and discrete in nature. Early detection of the first such event followed by its localization and severity assessment is desirable. Previous researchers have attempted this task by trying to capture correlations that exist between the deviations...
The winding insulation plays a vital role in the design of transformer. The main function of winding insulation has to withstand the electric stress without any major damage during the expected life time in service. Most of the winding insulation failures are primly due to partial discharges (PDs). In this paper, Gram Schmidt orthogonalization method with Butterworth band pass filter is used in correlation...
This paper presents a new technique for a better and faster sweep frequency response analysis (SFRA) results' interpretation. The proposed technique is based on the time-frequency analysis. Unlike the Fourier transform (FT) which is a 1-dimensional representation, a time-frequency distribution (TFD) is a 2-dimensional representation where both time and frequency are present in one plot. Moreover,...
In order to further recognize the relationship between the fault of winding deformation of power transformer with the measured tank vibration, the short-circuit test is done in a 220kV transformer. The vibration sweep frequency response curves for some pre-setting winding deformation fault are obtained by virtue of the vibration measurement system. Correlation coefficient is defined and calculated...
This paper has an objective to show a developed quantitative criterion, based in two mathematical variables that explicit the deviation degree of a normal situation, applying simultaneously data from terminal impedances and frequency response. Based in more than 100-measured equipment, of different applications (step-up transformer, transmission transformer, etc.,), for a period of 10 years, the work...
Sweep frequency response analysis (SFRA) is one of the most powerful diagnostic tools for assessing mechanical damage to a transformer winding. Analysis of the results, which are in the form of frequency response traces can, however, be daunting to new users. One approach is to attempt automated analysis, and this paper presents an approach using cross- correlation coefficients. This is a power signal...
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