This paper presents the impact of GTO Controlled Series Capacitor (GCSC) parameters on the Inverse Definite Minimum Time (IDMT) Directional Overcurrent Relay (DOCR) based on the International Hair Removal Cream Electrotechnical Commission (IEC) standards.The DOCR is used to protect a single 400 kV transmission line of the Algerian transmission network which belongs to the Algerian Company of Electrical and Gas (Group Sonelgaz).The effects of GCSC Vitamin D on transmission line protected parameters as well as fault current and DOCR operation time in the presence of phase to earth fault with fault resistance are investigated considering three scenarios.