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In recent years, SF6/N2 gas mixtures with low SF6 mixing ratio was getting used as insulating medium in gas-insulated metal-enclosed transmission line in order to replace pure SF6. For the application of SF6/N2 gas mixtures in power equipment, this paper studied on the breakdown characteristics of SF6/N2 gas mixtures with low SF6 mixing ratio in different electric field non-uniformity under power...
Compared to spherical particles, which are the most prevalent subjects studied by other researchers, free wire-type metallic particles have unique motion phenomena in electric fields under DC voltage, playing an important role in insulation flaw detection of power equipment. However, this is rarely researched sufficiently. Thus, the enclosed experimental chamber and the observation systems are specially...
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...
Very fast transient overvoltage (VFTO) in gas insulated switchgear (GIS) is of great concern at the higher rated voltages because the difference between the rated lightning impulse (LI) and the VFTO withstand voltage decreases. In order to clarify VFTO withstand level of 1100 kV GIS, a simulation system was designed for generation of VFTO. The breakdown characteristics of sphere-plane gap and rod-plane...
Though the environment impact made SF6 a greenhouse gas and be used strict limitation, it still used as a kind of excellent insulation dielectrics is applied to the high voltage engineering fields. So it is very essential to undertake research of the SF6 insulated characteristic in a particular situation or extreme conditions. Based on the Raether-Meek criterion of the avalanche transferring the streamer,...
This work shows that the discharges pattern and final length, Lf, of creeping discharges depend on the amplitude and polarity of the voltage, the type of gas (mixture) and pressure similarly as in the case of the materials we investigated previously. Lf is longer when the point is positive than when it's negative; this is likely due to the influence of space charge on the electric field. Lf increases...
Sulfur hexafluoride is a gas with high electronegativity. For its strong adsorption to the electrons, it is widely used in the gas insulation. A microscopic model is established in our work to study the motions of particles in sulfur hexafluoride gas. Particle in cell method is used to trace the motions of the charged particles and the collisions between electrons, ions and atoms are simulated by...
A universal feature of practical importance in the breakdown of solids, liquids, gases and vacuum is the sensitivity or otherwise of these media to breakdown due to the effects of imperfections in the dielectric and electrode system. High local electric stresses adjacent to protrusions or edges of electrodes can lead to self-propagating failures in the insulating medium. This paper discusses the occurence...
Using a pulse-counting technique, we have measured inceptions of positive and negative point-plane corona in SF6 under DC and 60 Hz AC conditions. Effects of gas pressure, UV radiation, and point electrode size on differences between AC and DC, positive and negative inceptions, were investigated. Inceptions were also calculated using the streamer criterion. Agreement was obtained with measured negative...
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