High voltage direct current（HVDC） filter capacitors may generate partial discharge owing to their original insulation defect or the insulation damages due to corrosion

vibration or damp

etc.Since partial discharge signals contain much information about insulation performance of the HVDC filter capacitor

measuring this information can help to evaluate the insulation property of the HVDC filter capacitor.This study aimed at the establishment of DC partial discharge test system for large capacitors

and conducted DC partial discharge tests to the analog capacitors with different types of defects on the basis of the partial discharge principle.By sampling data from the measuring system and post-processing

the characteristic parameter diagrams of DC partial discharge for different analog capacitors were plotted

and the discharge characteristics caused by different defects were compared.