Occurrence of partial discharges in low-voltage cables at the failure spot

Secondary cabling systems are usually not concerned as objects of diagnostic measurements. However, in case of power plants operating further after their originally planned lifetime, their reliability is a key issue. To perform their complete replacement to achieve the desired level of operation safety is not always economically and technically feasible. Partial discharge testing of low-voltage cables involves several issues that are fundamentally different from middle and high voltage cables. This paper addresses the most basic one, whether partial discharges occur at the failure spot at the relatively low test voltage of selected cable types. To avoid propagation questions, which are to be addressed in the future, as a first step shown in this paper, very short cable samples were prepared with injuries that are similar to those in real life. Partial discharge magnitudes, activity and other processed values were investigated from nominal voltage to test voltage, and the results are shown in this paper.