<p>Recent studies have focused on distinguishing permanent faults from transients and detecting secondary arc extinction. A simple method for detecting secondary arc extinction is to compare the measured voltages on the sides of the faulty phase with the threshold voltage. Along the faulty phase, a voltage drop (magnetic voltage) is created when the power flow (due to load) passes through the sound line conductors due to inductive coupling between the phases. As a result of this voltage drop, voltage deviations occur on both sides of the faulty phase, resulting in incorrect detection of the secondary arc extinction. To overcome this problem, a novel method has been developed, which relies on mutual communication signals between the substations on both sides of the line, allowing for the correct detection of the secondary arc extinction especially in high loading conditions of the line. Also, a novel formulation has been derived for the calculation of opened phase voltage in an untransposed line to threshold voltage adopting. To verify the validity and accuracy of the proposed method, some cases are implemented in EMTP by creating faults in different locations of a transmission line.</p>