Life estimation of distribution transformers using thermography: A case study

•The use of thermography is proposed to life estimation of distribution transformer.•The aim of the paper is to prove the ability of this technique.•Thermography is used to analyses the thermal of transformer body over time.•Experimental results show the effectiveness of proposed method. In the present study, a new method is offered for estimating the life of distribution transformers. So, it was attempted to determine the remaining lifetime of distribution transformers through using thermography from the body of 193 transformers used in Yazd Electric Distribution Company. To this end, environmental temperature, environmental humidity, and the transformers load capacity were calculated in tandem with thermography. Moreover, to test the offered method, oil samples of 49 transformers were collected, and their lifetime was estimated through conducting oil tests. The offered method determined the range of temperature changes of the transformers body for a three-year timespan using Bonferroni’s confidence interval estimation algorithm. These ranges were determined for 144 transformers and for the remaining 49 transformers, the estimated lifetime was measured through using the suggested algorithm and comparing them with the findings obtained from the oil test. This indicated the estimating accuracy of the suggested algorithm.