POWER ENGINEERING AND ELECTRICAL ENGINEERING VOLUME: 14 | NUMBER: 5 | 2016 | DECEMBER A Novel Method for Detection and Classification of Covered Conductor Faults Stanislav MISAK 1 , Michal KRATKY 2 , Lukas PROKOP 1 1 Centre ENET, VSB–Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava, Czech Republic 2 Department of Computer Science, Faculty of Electrical Engineering and Computer Science, VSB–Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava, Czech Republic stanislav.misak@vsb.cz, michal.kratky@vsb.cz, lukas.prokop@vsb.cz DOI: 10.15598/aeee.v14i5.1733 Abstract. Medium-Voltage (MV) overhead lines with Covered Conductors (CCs) are increasingly being used around the world primarily in forested or dissected terrain areas or in urban areas where it is not pos- sible to utilize MV cable lines. The CC is specific in high operational reliability provided by the conduc- tor core insulation compared to Aluminium-Conductor Steel-Reinforced (ACSR) overhead lines. The only dis- advantage of the CC is rather the problematic detection of faults compared to the ACSR. In this work, we con- sider the following faults: the contact of a tree branch with a CC and the fall of a conductor on the ground. The standard protection relays are unable to detect the faults and so the faults pose a risk for individuals in the vicinity of the conductor as well as it compromises the overall safety and reliability of the MV distribution system. In this article, we continue with our previ- ous work aimed at the method enabling detection of the faults and we introduce a method enabling a classifica- tion of the fault type. Such a classification is especially important for an operator of an MV distribution system to plan the optimal maintenance or repair the faulty conductors since the fall of a tree branch can be solved later whereas the breakdown of a conductor means an immediate action of the operator. Keywords Covered conductor faults, fault type classifi- cation, medium-voltage, overhead lines with covered conductors, Partial Discharges, PD- pattern. 1. Introduction The Covered Conductor (CC) have been primarily uti- lized for their high operation reliability guaranteed by the insulation compared to the ACSR. Consequently, the CC have been often used in forested or dissected terrain areas, in general, in all areas with extreme cli- matic conditions [1], [2] and [3]. Under these condi- tions, we can identify a high number of faults of the ACSR: the fall of a tree branch on the conductors, a phase-to-phase contact due to strong winds resulting in the phase-to-phase fault or, even, the breakdown of a conductor. Therefore, the CC have been used for MV distribu- tion lines for several decades. The major advantages of the conductor include: • A high operational reliability since no short-circuit appears at the moment of the phase-to-phase con- tact. • The individual phases can be located closer to one another and a demand on the protective zone of the overhead lines is lower compared to the ACSR. • No immediate phase-to-phase contact appears when a tree branch falls on the conductors, and finally. • The lines are not dangerous for birds sitting on the conductors. The only disadvantage of using the CC is a diffi- cult detection of faults when the conductor falls down on the ground. In this case, there is no single-phase- to-earth fault due to the insulation of the CC (let us note that it does not matter whether the conductor is broken). The standard protection relays work on the principle of an evaluation of the current or the voltage c  2016 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 481