An electric power system has a substation which is an important part of receiving electrical energy from the plant and then distributing it to consumers, where the substation has electrical equipment to support the process of sending electrical energy which if not properly protected when a disturbance occurs can damage the equipment and have the price is quite expensive, so that a good electrical protection system is needed, which is selective, sensitive, fast, reliable, and economical to maximize shipping that is able to feel, provide the reliability of electric power distribution systems and minimize interference and damage especially in main transformers. In this final project research discusses the analysis of differential relay coordination coordination as the main safety and overcurrent relay as a backup and overcurrent protection on the transformer to avoid protection failure by comparing the results of manual setting calculation data and installed settings in the field then performing simulation using ETAP software 12.6 to find out the simulation of the relay relay. Overcurrent relay is used as overcurrent protection relay which will describe the circuit breaker when the current exceeds the limit value setting against two secondary CT currents that are used against interference in the protection zone.