Transformer Condition Assessment
TCA ^TM


For many years, dissolved gas analysis and fluid quality testing have been used as diagnostic tools for transformers. By far, the most widely accepted standards for transformer fluid testing and interpretation in the last decade have been the 1991 revision of the IEEE guides, C57.104 and C57.106. TJ/H2b Analytical Services has used the knowledge gained from the application of these guides as a foundation for the development of enhanced diagnostics. In particular, TJ/H2b has developed diagnostic enhancements that include:

• Expanding the number of fluid assessment tests
  
• Updating pass/fail fluid assessment limits for newer maintenance philosophies
  
• Trending the relationships for fluid data
  
• Analyzing the relationships between fluid and gas data
  
• Trending gas-in-oil data beyond two tests
  
• Relating gas-in-oil data to phenomena in the transformer
  
• Assessing solid insulation condition
  
• Considering the relationship of these data to operation, system events, or maintenance activities
  
  

In 1997, TJ/H2b began to look at fluid testing possibilities that would provide the capabilities required for upgraded transformer maintenance programs.The ability to use transformers up to their maximum safe loading capabilities is essential to optimizing their use. Necessarily, obtaining the optimal use of transformers changes the approach to maintenance. The major critical asset components of a transformer, the paper, windings and core were not designed to be maintained in the same manner as the components of tap changers or breakers. In a manner analogous to human health care, a combination of preventive practices, prudent operating practices, treatments and repairs are needed. Management of the asset requires the best use of these alternatives and this, in turn, requires the appropriate condition assessment tools.

Transformer Condition Assessment, TCA^TM has been developed to provide the information for management of the oil condition, management of the paper condition, and the identification of the problems such as core lamination problems, core ground problems, no load tap changer problems, terminal and connector problems.

TCA^TM gave a condition 4* and indicated severe heating, possible coking, and aching at a connector or contact adjacent to but not directly in contact with paper. Internal inspection revealed a loose bolt on a load side bushing connector that had developed a large coke formation. This formation led to arching that had begun to deteriorate the connector.