Advances in the interpretation of transformer Frequency Response Analysis (FRA)

Summary

Measurement of frequency response is now commonly used to assess the mechanical integrity of the active part of power transformers. The analysis of the results, so-called Frequency Response Analysis (FRA), is based on comparison with a reference measurement which is either a previous measurement on the same unit, a measurement on an identical transformer, or a measurement on another phase of a three-phase transformer. Even if the method has recently been studied at the international level in various working groups under the umbrella of the CIGRE, IEC and IEEE organisations, there was still a need in the industry to obtain more guidance on the interpretation of the results. In this context, CIGRE WG A2.53 was created in 2016 and the resulting Technical Brochure (TB) covers the following topics:

• General and fundamental understanding of the frequency response;
• Factors that can influence the measurement and therefore the interpretation;
• Case studies showing how FRA can be used to detect mechanical failure modes and other electrical failures;
• Literature review of quantitative FRA assessment;
• Evaluation of numerical indices performance, over some key technical parameters, using data from academic experiments with controlled winding mechanical displacements and selected WG A2.53 case studies.

Additional informations

Keywords

power transformers, reactors