EXPERIMENTAL STUDY OF SF6 GAS-PRESSURIZED LAPPED-POLYPROPYLENE CABLE FOR EHV TRANSMISSION LINE
Problems on the materials and construction of SF 6 gas-pressurized lapped-polypropylene cable were mainly investigated to prevent the cable from deteriorating in electrical properties caused by thermal or mechanical stress applied to the cable. Biaxially oriented PP film (130 ˜ 200 μm thick) with fibrillated surfaces was used for insulation and in order to suppress the lowering of discharge inception voltage caused by loading cycles, aluminum-evaporated PP film which has the same thermal expansion coefficient as that of insulation was adopted for the inner and outer shielding layers. The partial discharge inception stress of 275 kV PPGF cable was in agreement with the theoretically highest-possible value in the butt spaces which exist in the insulation layer, and an impulse breakdown stress of more than 100 kV/mm was obtained.