The power demands of Brazilian national industries need an economical solution to increase power transmission capacity of existing transmission lines. Due to environmental and economical difficulties for construction of new power transmission lines, the use of fixed series compensation (FSC) has turned into a common practice of power transmission companies in Brazil. The FSC is presented as the best choice, because not only does it make possible to increase power transmission capacity as well as it stabilizes the interconnected energy nets through reduction of the impedance of the transmission line. The main purpose of this work is to present the FSC protection evaluation installed at Rio Verde 230 kV substation with 216 MVAr (FURNAS Centrais Eletricas S.A. - Brazilian Power Transmission Utility). This evaluation will be realized simulating faults internal and external to the 230 kV transmission line where the FSC were installed. The final conclusion of the work is to present the importance of the FSC to a transmission system and a complete evaluation of the FSC protection, observing the dimensioning and the situations that this protection operates in the transmission system with the purpose to keep the energy flow against faults due to lightning discharges and other causes.