This thesis explores the innovative use of broadband communication technology over power lines, known as Broadband over Power Line (BPL), for diagnosing the technical condition of Medium Voltage (MV) cable lines. The aim of the work is to demonstrate that this technology, primarily intended for data transmission, can also fulfill a secondary function as a sensor for on-line monitoring and the early detection of degradation processes in the distribution grid.

The thesis introduces a new diagnostic method, Condition Diagnostics over Broadband Power Line (ConDi-BPL), which integrates physical and topological parameters of the cable route, obtained from a Geographic Information System (GIS), with real-world measured communication data. The output of the method is a unified technical condition coefficient that quantifies the degree of degradation and enables grid operators to effectively prioritize maintenance. The applicability and functionality of the method are demonstrated in a case study of real routes from a distribution grid.

A key experimental part of the thesis is the validation of BPL technology's ability to detect partial discharges, which are an early indicator of insulation failures. Through controlled laboratory measurements, it was unequivocally demonstrated that the presence of artificially generated partial discharges, even at a low intensity of 50 pC, causes a~statistically significant and repeatable decrease in Transmission Control Protocol (TCP) throughput.

The results of this work confirm that BPL technology represents a low-cost and effective tool for the transition from reactive to proactive, data-driven maintenance. It thus contributes to enhancing the reliability of distribution grids and to the development of the smart grid concept.