Title :
Discharge mechanism at hvdc polarity reversal in oil / pressboard composite insulation system
Author :
Okubo, Hitoshi ; Saito, Hikaru ; Kojima, Hiroki ; Hayakawa, Naoki ; Kato, Katsumi
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Nagoya Univ., Nagoya, Japan
Abstract :
At the instant of polarity reversal of HVDC, very high electric field was generated in oil because the applied electric field was superimposed by the electric field of accumulated charges on pressboard (PB). When the total electric field exceeded the breakdown electric field strength, breakdown discharge in oil gap and surface discharge on the PB occurred. In this paper, by electric field measurement using Kerr electro-optic technique and optical observation, breakdown discharge characteristics and mechanisms in oil/PB composite insulation system were investigated at polarity reversal voltage. We revealed that the surface discharge neutralizes the accumulated charges on PB. The above experiments were carried out for different PB arrangements and discussed the discharge characteristics under HVDC polarity reversal conditions were discussed.
Keywords :
Kerr electro-optical effect; electric breakdown; electric field measurement; insulating oils; surface discharges; HVDC polarity reversal; Kerr electro-optic technique; breakdown discharge characteristic; breakdown electric field strength; discharge mechanism; electric field measurement; oil gap; oil-PB composite insulation system; oil-pressboard composite insulation system; optical observation; polarity reversal voltage; surface discharge; Discharges; Electric fields; Electric variables measurement; Electrodes; HVDC transmission; Insulation; DC conveter Ttransformer; HVDC transmission; Oil / Pressvboard insulation; Polarity reversal;
Conference_Titel :
Dielectric Liquids (ICDL), 2011 IEEE International Conference on
Conference_Location :
Trondheim
Print_ISBN :
978-1-4244-7352-6
Electronic_ISBN :
2153-3725
DOI :
10.1109/ICDL.2011.6015443
