Quality assessment of HVDC components by PD analysis

HVDC components for both energy (HVDC submarine cables) and non-energy (X-ray equipment, television screens, travelling wave tubes) applications can successfully be tested for partial discharges (PD). Contrary to the situation for ac equipment that is used for the electrical energy supply (IEC270), no detailed PD testing procedures are available for dc. ASTM 1868 only mentions "repetitive pulses of more than one per minute". In this paper, the merits of PD testing will be shown for several HVDC components. By carefully representing the PD data, a surprising amount of information can be obtained on the PD generating defect. The conclusion is that PD analysis, specially designed for dc, can be of great help when designing and testing HVDC equipment.