Temperature Prediction in Cast-Resin Transformer Due to Non-Linear Loads

Abstract

Knowledge about temperature distribution in dry-type transformers is so important and useful. Resin in cast-resin dry-type transformer causes the heat transfer to be decreased; this leads an increase in the temperature of transformer. Following this subject, it is obvious that a thermal modeling for this type of transformer is necessary. If loads assume to be linear, temperature can be analyzed without harmonics but now almost the loads in the residential and industrial networks are nonlinear. Loads as computers, florescent lamps, motors and etc. cause voltage and current to have harmonics in addition of fundamental component. In this paper, first a method for temperature prediction in the cast-resin dry-type transformer has been introduced. After verifying the thermal model with the help of experimental data, current's harmonics are applied to the thermal modeling and their effects on temperature distribution have been discussed. Finally it has been shown that, non-linear loads have noticeable effects on temperature distribution and their effects must be considered in design procedure of cast-resin dry-type transformers.