Analysis of The Effect of Ambient Temperature and Loading on Power Transformers Ageing (Study Case of 3rd Power Transformer in Cikupa Substation)

Power transformer is one of the most important and vital equipment in the substation. Power Transformers in Indonesia are mostly designed to refer to IEC standards. according to the IEC standard, power transformers are used at an ambient temperature of 20 °C. While as a tropical country, the average temperature in Indonesia is around 30 °C. Environmental temperature differences in design and real conditions make a transformer very risky to operate to reach its maximum capacity. Because of this, the transformer's operating must be adjusted. With a higher ambient temperature plus a higher load, the ageing of the transformer is also faster. The age of the transformer can be affected by the insulation of the winding and the condition of oil transformers.This research studies the effect of loading and ambient temperature which can reduce the lifetime of the transformer. The transformer which is the object of the research is 3rd power transformer in the Cikupa Substation.The results showed a decrease in transformer loading capacity at ambient temperatures above 20 °C. with the rate of increase 1,06% - 1,2% for ONAN condition and 0,87% - 0,96% for ONAF condition in the ambient temperature range 21 °C - 35 °C.