Validation of the forensic analysis applied to distribution transformers (FAADT)

Most Brazilian utility companies normally do not consider failures in distribution transformers to be a great economic issue, since detecting these faults can be more costly in terms of time and resources. Thus, proper policies for investigating faults in distribution transformers are usually disregarded by the power utilities and sometimes policies may not even exist. In this context, existing information on faulty distribution transformers may not contain important data. However, new laws affecting power distribution companies are becoming more severe and there are demands for greater efficiency. In this new scenario, a forensic methodology to analyze faults in distribution transformers, created some years ago by many utilities, has recently been resurrected with the analysis of 3,159 distribution transformers. This methodology is known as Forensic Analysis Applied to Distribution Transformers (FAADT). This paper, which analyzes eight damaged distribution transformers, randomly selected from ELEKTRO´s distribution lines, validates and refines the FAADT methodology. In order to do this, in addition to FAADT parameters, other parameters, such as polarization and dielectric absorption indices, turns ratio, insulation resistance and physicochemical analyses were also verified.