Abstract: Arc interruption of High Voltage Direct Current (HVDC) Circuit Breakers (CBs) is one of the main challenging factors for using HVDC grids. To evaluate the arc interrupting capability in HVDC circuit breakers, black box arc models are used to represent the non-linear arc conductance depending on Cassie and Mayrdynamic arc equations. A real line represents a part of 500 kV electrical connection systems between Egypt and Kingdom Saudi Arabia is simulated to be a faulty load. It is found that the arcing voltage and thearcing time of the HVDC CB can be reduced by decreasing the value of arcing time constant( ) and increasing the value of power cooling coefficient (P) It is also deduced that the arcing time is reduced by the increase of the commutation capacitance value (C) and decreasing the commutation inductance (L) value and vice versa. Moreover, it is concluded that the arcing voltage of HVDC circuit Breaker is greatly affected if more than one pole (cascaded series or parallel two or three poles) are used for single circuit breaker and this would be more effective and better for commercial reasons than using cascaded series or parallel two or three circuit breakers.