A power transformer is most costly and essential equipment. So for getting high performance and long functional life of the transformer, it is desired to perform various maintenance activities. Not only that, a power transformer also requires various maintenance actions including measurement and testing of different parameters of the transformer. There are several types of maintenance of transformer. Some of them in yearly basis, some are half-yearly basis, some of them are quarterly basis, some other are monthly basis. There are some maintenance which to be performed in 4 to 5 years interval.