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Insulators are under residual DC voltage after opening of disconnectors. When disconnectors reclose, overvoltage will be superimposed on the pre-existing DC voltage. As a result, insulators in GIS will be under combined voltage of DC and impulse. In this paper, flashover characteristics of insulators in SF6 are studied under combined voltage of DC and lightning impulse. The results show that for non-contaminated...
The basin-type insulator is one of the most important parts in SF6 gas insulated switchgear (GIS). Flashover of basin-type insulators will cause serious harm to the electrical system. The fact that metallic particle attached to the surface cannot be detected in the delivery test under the standard lightning impulse (SLI) will pose potential threat to GIS. This paper studied flashover characteristics...
Excess moisture in GIS will condense on solid insulating materials under certain environmental conditions and cause the reduction of flashover voltage, thus threatening its normal operation. To formulate proper standard of moisture content in GIS, it's necessary to study the influence of moisture on the dielectric strength of insulators. In this paper, the influence of moisture on the flashover voltage...
It is of great significance to detect different defect types of HVDC bushings effectively for the safe operation of power system and the condition maintenance of power transformers. In order to simulate the insulation defects of the main insulation of the HVDC bushings, five samples of the main insulation of the HVDC bushing with a maximum DC voltage of 30kV are fabricated by a vacuum impregnation...
The flashover of insulators is a bottleneck for the development of gas insulated transmission line (GIL). The operation experience of GIL shows that metallic particle plays an important role in flashover of the insulator. An experiment platform was established to study the influence of gas pressure on the flashover characteristics of the post insulator in SF6 under negative DC voltage. The impacts...
Flashover of contaminated insulators is one of the major problems for the power distribution, especially in high altitude area. Laboratory experiments have shown that low pressure have great influences on the flashover performance of outdoor insulators. In order to investigate the influence of low pressure on the characteristics of AC partial arc, an experimental system was designed in this paper...
In recent years, SF6 gas insulated switchgear (GIS) is increasingly widely used among the power system of China and the flashover characteristics on GIS insulator have attracted widely attention of many researchers. According to the previous research, it's found that surface conditions of the insulators have a great impact on flashover voltage. In this paper, the influence of the surface roughness...
Gas-insulated switchgear (GIS) is widely used today in electrical power systems because of its reliability, compaction, long maintenance cycle, and small impact on the environment [1]. In its use the normal operation of the disconnector generates very fast transient overvoltages (VFTO) with frequencies ranging from 1 to 100 MHz [2] and amplitudes up to 2.5 p.u. [3]. For systems above 330 kV, the insulation...
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