An Extensive Study on Condition Monitoring of Distribution Transformer under Transients
Keywords:
Frequency dominations, transients, Fast Fourier Transform, Distribution transformer, High frequency modelingAbstract
Power transient faults on high voltage lines mainly occur at high frequencies. These high frequency transients affect the predicted life and efficiency of equipment. Generally, Real time testing of transformers is performed to obtain digital data. FFT analysis is applied to see the incorporation of frequencies. Models are developed at different frequencies with respect to tested specimen. Frequency response analysis is also used for the diagnosis. The major case of study is; to define the frequencies incorporation based on transformer resonating core of a particular transformer. Under the influence of high voltage (HV) transient, change in impedance of the transformer has been observed by transfer function method; this change in impedances gradually degrades the life of a core. In this research, the idea is to define the frequencies i.e. single or dual core resonant frequencies dominations with respect to different rating of the transformers, which are helpful for scholars in a generic way to perform characteristics analysis and modeling a design. Firstly, transformers of different ratings i.e. 100, 50 and 30 kVA are investigated in the published researches. Secondly, an experiment is performed on 25 kVA transformer, then a concept has been developed which defines the single resonance behavior practically occurs at equal or less than 50 kVA; above 50 kVA i.e. 100 kVA transformer core resonates twice. Results have shown that this concept, defines the core deviating frequencies with respect to the ratings.
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