AC Surface Flashover and Gas Generation Difference of the Cellulose Insulation Pressboard Immersed in Novel 3-Element Mixed Oil and Mineral Oil

Abstract

Surface flashover fault is one of the most challenge issues in oil-cellulose insulation pressboard system used in power transformer. In this study, a comparative study of the AC surface flashover properties of the novel 3-element mixed oil-cellulose insulation pressboard (3EMO-IP) and mineral oil-cellulose insulation pressboard (MO-IP) was performed under needle-plate and finger-finger electrode, respectively, measurement including dielectric property, surface flashover voltage, damage of cellulose pressboard surface and the gas generation behaviors after multiple surface flashover. Results show that the cellulose insulation pressboard immersed in the novel 3-element mixed insulation oil (3EMO) has higher relative permittivity and dielectric loss factor at 50 Hz, and also has slightly lower surface resistivity. The AC surface flashover voltage of the 3EMO-IP is higher than that of MO-IP under needle-plate and finger-finger electrode (electrode distance 5 mm, 10 mm, 15 mm and 20 mm). Compared to MO-IP, the lower electric field intensity at the oil-pressboard interface, as well as more difficult for surface charge accumulation of 3EMO-IP and the higher breakdown voltage of 3EMO lead to the higher AC surface flashover voltage of 3EMO-IP. Moreover, the carbonization of fibers in 3EMO-IP is slightly less. After multiple surface flashover, C 2 H 2 and total hydrocarbon gases are the main differences between 3EMO-IP and MO-IP, which is more marked with the increase of flashover times. This study offers a reference for improving the surface flashover property of oil-pressboard insulation system by using 3EMO.

Performance Analysis Of Electrical Properties Of Resin Transfer Molded Banana Leaf Reinforced Polymer Composites

“…Complete orientation of molecules can only be achieved at lower frequencies, and orientation polarization takes longer to reach equilibrium static field values than electronic or atomic polarizations, indicating that it is more difficult to achieve complete orientation. The result is that when frequency increases, ɛ 0 drops as a result of the time delay in polarization orientation [1]. The orientation of the filler and the interfacial polarizations are also affected by the amount of filler present.…”

“…It is possible to derive the volume resistivity (q) from the resistance by use the equation. ρ = RA-t (1) where V represents volume resistivity, R represents resistance, A represents the crosssectional area of the sample, and t represents the thickness of the sample…”

“…Many different fibers and plants are used as reinforcements in the production of composites. Some of the most commonly used fibers and plants are flax, hemp, oil palm, coir, jute, kenaf, and banana [1][2][3][4][5][6]. Natural fibre composites have several advantages over synthetic fibre reinforced composites, including the use of renewable raw materials, low cost, light weight, and high specific strength and stiffness.…”

Effect of Temperature on Creeping Flashover Voltage of Nanofilled Oil-Pressboard Insulation

“…11 describes the mechanism of creeping flashover voltage occurrence along oil-pressboard interface. Negative charges are formed within the pressboard as it has the higher relative permitivitty than the transformer oil [18]. Then, positive surface charges are attached to the pressboard surface due to the attraction force with the negative charges within the pressboard.…”

“…However, few ones deal with their effect on creeping flashover voltage of oil-pressboard insulation. The concept of mixing two types of vegetable oil with the base mineral transformer oil (3-element mixed insulation oil, 3EMO) for enhancing flashover voltage at oil pressboard interface is studied in [18]. It is also reported that using 3EMO impregnated pressboard has a slightly higher relative permittivity and a lower percentage of dissolved gases during flashover.…”