The most easily accessible and efficient way to determine transformer condition is to use the fluid as the diagnostic medium. It has been estimated that transformer fluids contain about 70% of the available diagnostic information for transformers. The challenge is to access and use it effectively. Traditional transformer oil-test programs utilize only a few diagnostic parameters leaving a myriad of important oil based information unused. Surveys of failed transformers have revealed that many failures can be attributed to problems that could have been property managed with a more detailed analysis of the insulating fluid.
To meet the demand for an improved transformer management tool, TJIH2b Analytical Services has developed Transformer Condition Assessment, TCA®. TCA® offers a comprehensive assessment of the dielectric and mechanical state of the transformer through the analysis of the transformer insulating fluid. The TCA® test selection includes application from the field of microscopy, providing a better understanding of the problems and risks associated with continued transformer operation.
After performing a TCA® analysis on your transformer, you will receive a condition rating. The recommended sampling interval ranges from ‘immediately’ to ‘annually’, depending on the condition of your unit. Please refer to the scoring methodology or reach out to TJH2b for further explanation on recommended intervals.
TCA™ condition codes, in general, indicate the following+:
+Some variations of the recommended mitigations or retest intervals may occur at the discretion of the laboratory based on information provided. With transformers, we are dealing with a complex subject involving a number of variables. As such, general “rules of thumb” with regard to sampling intervals cannot be applied in every case. A number of other factors must be taken into consideration, such as:
As such, the appropriate action is up to the discretion of the Asset Manager who is best placed to take other influencing factors into account according to established internal procedures. Our codes and recommendations, while based on a vast amount of experience as well as guidelines published by IEEE and other standards bodies, are to be taken only as useful guides.
A Transformer Condition Assessment (TCA®) includes a condition rating, diagnostics, and potential remediation actions where applicable. Upon receipt of the report from TJH2b, we recommend that results and diagnostics are reviewed promptly, following internal procedures. If further support is needed, TJH2b offers free, 24/7 consultation services to help you understand reports and provide guidance.
TJH2b recommends following the latest revision of ASTM D923 (Standard Practices for Sampling Electrical Insulating Liquids) or an equivalent standard in order to ensure consistent, high-quality sampling practices. TJH2b has developed a tool to help you meet the standard and take a proper, representative sample every time: Turbulent Flush Sampling System.