Kerr Electro-optic Field Measurement and Electrical Insulation Techniques in HVDC Oil-Pressboard Composite Insulation Systems

The following technical items were investigated and concluded: Firstly, a Kerr electro-optic electric field measurement technique was introduced for the direct measurement of electric field distributions and charging activities for a pressboard (PB) arrangement in oil, for DC voltage and DC polarity reversal conditions. Next, under different PB arrangement in oil, the time dependent electric field stress behaviours were measured under DC and DC polarity reversal (PR) conditions and the physical mechanisms of the movement and accumulation of charge carriers in the insulation systems were clarified. Moreover, it was observed that the charge accumulation characteristics and hence the stress distributions were dependent on the PB arrangement of the actual oil duct model, as well as on the…