Substations are a fundamental part in electrical energy transmission and distribution. The role of a substation is to transfer and transform electrical energy by stepping up or down the voltage. To do this, high voltage switching equipment and power transformers are used, in addition to instrument transformers that supply the status of the primary system to the secondary equipment. Substation Automation Systems are then used to control, protect and monitor the substations. The IEC 61850 standard developed digital substation with most advanced techniques. The IEC 61850 standard define in its sub-clauses IEC 600448 and IEC 61850-9-2 about digital interface, digital communication and Sampled Values transmission over an Ethernet link called Process Bus. Process Bus technology mainly developed in order to reduce the usage of copper wiring at substation control by introducing IEC 61850-9-2 digital interface.