Abstract A realistic representation of the secondary arcs is essential in determining the auto-reclosure performance of EHV transmission lines. In this paper the dynamic behavior of the arc is presented as a time-varying resistance using the MODELS feature of the ATP–EMTP program. It is shown that random variation of the arc parameters influences significantly the arc extinction time besides the capacitive and inductive coupling between the faulty and the sound phases. Parameters for the arc model have been extracted from staged fault tests records carried out on a double-circuit, uncompensated 400 kV interconnecting line. The results of the simulation proved the importance of the distributed nature of the transmission line and the nonlinear characteristic of the arc resistance in the intermittent region of arcing. The arc current is determined by wave processes in this interval. As a result, the continuous current characterizing the first period of secondary arcing is followed by individual current impulses of much higher amplitude. The high energy re-ignitions of the second period may push back the arcing process into the continuous condition, which multiplies the self-extinction time.