Iranian Journal of Electrical and Electronic Engineering

This paper presents an algorithm for adaptive determination of the dead time

during transient arcing faults and blocking automatic reclosing during permanent faults on

overhead transmission lines. The discrimination between transient and permanent faults is

made by the zero sequence voltage measured at the relay point. If the fault is recognised as

an arcing one, then the third harmonic of the zero sequence voltage is used to evaluate the

extinction time of the secondary arc and to initiate reclosing signal. The significant

advantage of this algorithm is that it uses an adaptive threshold level and therefore its

performance is independent of fault location, line parameters and the system operating

conditions. The proposed algorithm has been successfully tested under a variety of fault

locations and load angles on a 400KV overhead line using Electro-Magnetic Transient

Program (EMTP). The test results validate the algorithm ability in determining the

secondary arc extinction time during transient faults as well as blocking unsuccessful

automatic reclosing during permanent faults.