Studies of Voltages Induced in the Screens of Power Cables Using Computer Simulation on an MV Network Model

One of the reasons for using metallic sheaths in power cables is to provide a path for fault current flow. The aim of the study will be to determine the effect of the type of short circuit, the current that flows in the conductor of a three-phase MV cable line, on the level of voltages and overvoltages induced in the metallic screens of these cables with different configurations of their grounding. The appearance of voltage exceeding safe values in the screen can lead to damage to the outer sheath insulation cable. The simulation studies were carried out using an MV network model created in the DIgSILENT Power Factory program, which consists of basic elements of the power system and a system that duplicates connections of sheaths and grounding. The test results show the waveforms of voltages induced in the cable screens and the maximum values of overvoltage resulting from the simulation of ground faults and phase faults. The main achievement obtained as a result of the simulation tests was obtaining information on the level of overvoltage hazard in the event of various types of short-circuit disturbances. The analysis of the obtained results indicates the possibility of overvoltage in the considered system, posing a threat to the outer sheath of the cable; therefore, a solution will be proposed to avoid damage.