a New EPRI Commercial Prototype FRA Installation at First Energy

The electric utility industry is in the age of transition from periodic maintenance to predictive or conditioned based maintenance on essential substation power transformers in an effort to lower maintenance costs and maximize the use of existing equipment. The development of new on-line diagnostics is in the critical path to achieve the predictive maintenance goals for power transformers. EPRI has partnered with NEETRAC since the beginning of the on-line FRA development in 2003. The initial data from the first on-line FRA installation was recorded in 2004 and presented at the February, 2004, EPRI Conference in New Orleans, LA [10]. This paper includes key points of the current NEETRAC on-line FRA [1, 3] and the most recent developments towards a viable commercial prototype for the EPRI First Energy project. In particular, equipment upgrades and relocation as well as downsizing along with wireless data communication from the transformer are discussed for the new installation. The commercial prototype on-line FRA is to be installed on a 345 / 140 kV, 448 MVA, auto-transformer at First Energy’s Star Substation in the second quarter of 2009. Utility Need / Background Fault data compiled from four of the National Electric Energy Testing, Research & Applications Center (NEETRAC)’s member utilities indicates that 5.0% of distribution buses and 8.8% of transmission buses have maximum fault levels exceeding the 30 kA mark. The problem of transformer winding deformation, especially on older power banks, is increasing due to long-term exposure and the continued growth of the power grid. A practical and consistent on-line winding deformation and dielectric degradation technique would be very valuable for transformers, especially for those that benefit the most from condition-based maintenance, such as large, essential, power banks on the transmission system. Many utilities are already using some form of off-line (transformer de-energized and switched out of service) Frequency Response Analysis (FRA) on new and existing transformers because it is well-known to be sensitive to winding distortion. At this time, FRA is the only technology that is sensitive to significant winding deformation (coils, layers, turns, leads etc.) in power transformers. A significant amount of deformation can