Abstract

This study presents the results of Sweep Frequency Response Analysis (SFRA) measurement work carried out on number of power transformers at various sites involving problems like shorting of winding turns, core faults and related issues, On-Load Tap Changer (OLTC) open contacts and winding displacement issues. The numerical parameters Viz., Min-Max ratio (MM), Mean Square Error (MSE), Maximum Absolute difference (MABS), Absolute Sum of Logarithmic Error (ASLE), Standard Deviation (S.D.) and Correlation Coefficient (CC) computed in three different frequency bands are presented to aid the interpretation of SFRA data. Comparison of frequency responses among different phases of the same transformer and with sister units were carried out to interpret the data. The study presents limits for various numerical parameters to diagnose the condition of the transformer and discriminate the faulty winding after accounting for manufacturing, design and asymmetry of the winding. The results presented in the study will help in interpreting the SFRA data by applying numerical techniques and assess the condition of the transformer.

Keywords:

Condition assessment, deformation, displacements, numerical approach, SFRA,

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Competing interests

The authors have no competing interests.

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