Medium Voltage Covered Conductors: Advantages, Disadvantages and High Impedance Faults

Covered conductors represent an alternative to classic ACSR for overhead high-voltage distribution lines. They were first put into operation in the 1970s, especially in the USA and Europe at voltage levels up to 35 kV. Since the 1990s, with the spread of covered conductors with multi-layer insulation, they have gradually been deployed at even higher voltage levels. The constant growth of electricity consumption in combination with the planned development of electromobility and decentralized sources will place ever higher demands on the reliability of the medium voltage distribution network. Therefore, in order to increase the reliability and safety of operation, in 2014 work was started at VŠB-TUO on the development of an high impedance fault detector for these lines. Its development has continued since then, this work represents some of the experience from the development and long-term operation of this device.