A Review of Risk Assessment Driven Approach for Power Transformer Replacement That Considers Temperature, Apparent Age and Projected Capacity

Many power transformers have been lost due to improper planning of end-of-life failures brought about by fire from insulation breakdown, re-occurring faults, reduced transformer loading capacity, increased maintenance and repairs. Considering the cost of a power transformer and the down time effect to repair or replacement, proper planning of transformer replacement is very important. This would help to avert sudden pressures and improve transformer capacity delivery to end users. This study reviews steps on risk assessment approach for power transformer replacement, considering collecting transformer data, and identifies the network topology, load demand, failure rate, repair rate, transformer condition relative to the age modelling approach. It also reviews measuring carbon compounds that reflect the ageing indicator of the insulation materials, bushing, winding and tap changer of the transformer. Methodologies for calculating projected power transformers capacity and ranking index and for figuring out the ideal replacement year are reviewed. The winding hottest spot temperature and apparent age would be integrated into the current end-of-life failure model to provide improvement in decision-making regarding the replacement of transformers. Utilizing the substation transmission and distribution reliability test systems, the performance of the technique would be assessed, and outcomes will show that failures of fans and oil pumps at the end of a transformer’s life could affect replacement decisions.