Electric Faults can be defined as the flow of a massive current through an alternative path which leads to cause serious equipment's damage, interruption of power, personal injury or death. High Voltage Alternating Current (HVAC) is the most effective and efficient way for energy transmission in modern power systems around the world. But, it's important to use High Voltage Direct Current (HVDC) system to link between different frequency networks and at transmitting energy on very long distance. HVDC operates at one side "converter station", where, the AC is converted to DC, which is then transmitted from sending end converter station, converted back to AC at receiving end to feed the other electrical network. This paper discusses the performance of the electrical grid system at the fault occurrence in HVAC and HVDC system. Also, this paper introduces the mathematical calculation steps at different faults conditions in the transmission line. The simulation of the fault current in this paper has been performed by using MATLAB/Simulink to compare the output fault current in HVAC and HVDC system.