Life Assessment of Aluminium and Copper Winding Distribution Transformers Using Loss of Life Analysis

In general, the life of distribution transformers is very dependent on the conditions of oil insulation and windings. Some disturbance conditions and the transformer overloading capacity can cause a high-temperature rise and accelerate the decrease in insulation level so that the loss of life of the transformer can be even greater. While the recent population of distribution transformers mostly consist of Copper (Cu) and Aluminum (Al) windings. Based on that, this study determines the life time of distribution transformers for both technologies. Life assessment is executed using loss of life analysis due to the disturbance phenomenon called cold load pick up (CLPU) and loading conditions. Using 79 units Cu-Cu and 105 units Al-Al distribution transformers installed at PLN UP3 Cengkareng Jakarta, the loss of life is conducted using CLPU algorithm and IEC 60354 and 60076-7 calculation. The result of study found that the life time of copper winding is longer than aluminium winding transformers. In additions the total owning cost of transformer aluminium is higher 9% than the copper one.