Diagnozing The Integrity Of Transformer Windings Using Frequency Response Analysis Technique

Abstract

Power transformers are the most expensive and strategically important components of any power generation and transmission system and their failure is a very costly event. Monitoring and diagnostic techniques, which can evaluate the integrity of transformer winding, are essential to evolve optimum and better reliability of the equipment. There is no traditional method, efficient enough to detect the winding displacement/ deformation. Winding deformations in transformers are difficult to establish by conventional methods of diagnostic tests like ratio, impedance/inductance, magnetizing current etc newlineAdvanced techniques like LVI with Transfer Function (TF) method and Sweep Frequency Method (SFM) to obtain frequency responses can be applied, which are emerging tools, for detection of winding deformations/displacements. Even though these techniques are in use, research work on suitability of these techniques for repeatable measurements at site, diagnosis and interpretation of data for detecting various deformations in the transformer windings, is in progress worldwide. There are no acceptable limits set for the deviations in the FRA curves from their fingerprints. There are no clear guidelines for interpreting FRA data to unambiguously detect the faults in the transformers. The present research work is aimed at forming interpretation guidelines to diagnose the integrity of transformer windings using frequency response analysis technique. In the present work, sweep frequency response measurement method has been used to obtain the FRA data. newlineIn the present study, suitable core and coil assemblies are used for conducting experimental work. Experimental investigations are conducted to identify SFRA measurement sensitivity for detection of faults.