Transformer Condition Assessment: Methodologies and On-Site Repair Solutions

In this paper, the transformer condition assessment methodologies were describe as well as on-site repair solutions as a means to assess the reliability of transformers. The diagnosis of the transformer condition is used to recommend maintenance actions and identify defects before untanking the transformer. This allows maintenance personnel to anticipate the potential need for repair, thereby reducing the amount of time spent in the process, especially when transformers are being repaired on site. Repairing transformers on site usually allows them to be put back in service in a shorter time period (up to three months) by avoiding transportation from the site to the factory and back. In addition, it reduces the costs and risks associated with heavy transport. To date, more than 400 transformers, including utility, industrial, high-voltage direct current (HVdc), and reactors have been successfully repaired on site. In many cases, transformers were upgraded to provide an increased rating.