Current transformer (CT) is a device that transfers the electrical energy from one circuit to another through a shared magnetic field. In a CT, heat is generated in the core, tank wall, and primary and secondary windings. The performance of a CT is well indicated by the temperature distribution inside it. In this study, numerical analysis was performed to predict the temperature distribution inside the CT at every instant under different load conditions. It was found that the numerical results obtained were in good agreement with the experimental measurements. Thus, it was concluded that the numerical method can be a useful tool in CT design and performance monitoring.