Contents I. Introduction
Transformer parameters are closely related to the reliability and smoothness of the system in operation[1]. Transformer operation failure is certainly very much avoided by routinely performing maintenance and monitoring transformer performance periodically[2]. One of the causes of transformer failure is a disturbance in the electric power system. Disturbances that occur include overloading, short circuit, overvoltage, harmonics, lightning surge, insulation oil leakage, and the condition of the transformer oil[3]-[5]. Important parameters voltage, electric current and frequency are also important parameters that need to be monitored carefully. Other parameters that also need to be considered and maintained are harmonics, power factor (PF), frequency, temperature, pressure inside the transformer, and K-factor[6], [7].
