Transformers are one of the most critical and expensive components of any distribution system. Iti s a closed static device usually soaked in oil, so the failures that occur on it are limited, but the effect of a failure can be very dangerous for the transformer and the long time required to repair and replace the transformer makes things even worse. Therefore, the protection of power transformers has become very important. In this thesis, the concepts of transformer and its parts, alternative models of energy failures, types of transformer failures and transformer protection are explained. The types of protection used to protect power transformers are: differential protection, earth fault protection, overload protection, overcurrent protection, homopolar protection, etc. This thesis also describes the process of creating a scheme in the EPLAN software package, which was used for the subsequent calculation of the differential protection of the power transformer. EPLAN Electric P8 is an electrical design software solution that supports 2D computer-aided engineering for creating schematics and circuit diagrams. The software supports a variety of engineering methods including manual fabrication, template-based approaches, and standardized approaches.