Improving the Assessment of Remaining Life of Service Aged Power Transformers

A significant number of power transformers worldwide are displaying an ever-increasing trend of unreliable operation and shortened lifetimes, due to poor electrical or mechanical conditions and onerous loading situations. Monitoring the condition of these transformers and accurately predicting their useful remaining life is quite significant to utilities and/or independent owners especially considering the high replacement cost and criticality associated with the smooth functioning of these assets. In this regard, the condition of the insulation system plays a pivotal role in influencing the remnant useful life associated with power transformers. This paper provides a better estimation for determining the remaining life of a power transformer based on the results of an improved dynamic model. The model is an upgrade over the basic life expectancy formulation provided by existing IEEE and IEC standards in this domain and considers parameters such as hotspot temperature, moisture, oxygen, the ratio of carbon oxides (CO2/CO), the degree of polymerization (DP) and the concentration of furfural (2-FAL) or methanol (MeOH) as aging markers.