Introduction: Partial discharge (PD) is the breakdown of a small part of insulation on equipment that is under high voltage (HV) stress. It is one of the major causes of catastrophic failures in HV equipment. PD mechanisms in HV Alternating Current (AC) systems are well understood and there is a growing body of knowledge around effective detection, monitoring and mitigation techniques under these conditions. However, there is a lack of knowledge and experience in the industry relating to PD under High Voltage Direct Current (HVDC) conditions. SSEN is investing significantly in HVDC cables, a trend replicated by the rest of the GB industry where there is proliferation of interconnectors and connections to offshore renewable sources of energy. To better prepare for the growth in use of HVDC, there is recognition for the imperative to know more about the mechanisms and characteristics of PD under these conditions.

Objectives: To determine
1.       Partial discharge inception voltages, magnitude and frequency of discharges, pulse characteristics, and frequency domain profiles of the samples mentioned above
2.       To investigate and consider technologies for the detection of partial discharges in longer length (tens of kilometres) HVDC cables by investigating the attenuation of signals in both the time and frequency domains