Search Results (7)

Since the insulation performance of air is not as good as that of $S{F}_6$ and other gases, it is necessary to conduct an in-depth study on the insulation characteristics of the fuse tube in order to meet the requirements of normal breaking and to design a structural improvement scheme for a 12 kV environmental protection cabinet fuse tube that is suitable for using air as the insulating medium. In this study, the insulation performance of the fuse tube before improvement was studied, and the electric-field distribution of the 12 kV fuse tube placed in the air-insulated switchgear was analyzed. The results showed that the electric-field was heavily concentrated in the air gap of the fuse tube plug and around the ground rod. In this study, the structure of the fuse tube was specifically designed. By spraying conductive paint on the intersection surface of different media, equipotentiality was achieved, and a reasonable metal shielding structure was added to the site where the field intensity was concentrated so as to improve the distribution of the electric-field and avoid the breakdown caused by the concentration of field intensity. Through several improved designs, the maximum electric-field strength of the fuse tube of an environmental protection cabinet can be effectively reduced, and the insulation requirements of relevant standards can be met. A partial discharge test for the improved fuse tube was carried out, and the local discharge quantity of the improved fuse tube met the industry requirements, which verified the rationality of the fuse-tube-improvement scheme. Full article

C₅F₁₀O is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C₅F₁₀O are studied. The influence of C₅F₁₀O/N₂ mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C₅F₁₀O and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with C₅F₁₀O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO₃. This consequently reduces the compression modulus of NBR. The interaction is related to CF₃ radicals formed by the primary decomposition of C₅F₁₀O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF₃ on NBR’s backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters. Full article

SF₆, which is currently widely used in gas-insulated power transmission equipment, is a greenhouse gas with a very strong greenhouse effect. Therefore, developing environmentally friendly gas insulation equipment to gradually reduce the use of SF₆ has become a hot research topic. As the most potential alternative gas, C₄F₇N is of great significance to study the electrical characteristics of the medium-voltage switching field to promote the green development of the power industry. Based on multi-physical field coupling to construct the 40.5 kV circuit breaker mode, this paper uses C₄F₇N/CO₂ mixed gas to compare and study the dynamic characteristics of a C₄F₇N/CO₂ mixed gas circuit breaker when breaking the short-circuit current and the dielectric recovery strength with no-load breaking, as well as to evaluate the electrical performance of C₄F₇N mixed gas in a 40.5 kV breaker with the gas breakdown criterion. The results show that mixing O₂ in a high current can improve the breaking performance of an environmental protection circuit breaker and increasing the C₄F₇N mass fraction can enhance the dielectric recovery strength of the environmentally friendly circuit breaker. Considering the overall performance of the gas, the 5%C₄F₇N/90% CO₂/5%O₂ mixed gas has some alternative potential. Full article

This paper presents the results of testing the electrical strength of an insulating system in a vacuum obtained from three noble gases: argon, neon, helium, and air. The breakdown voltages were measured for contact gaps of 1 mm and 2 mm. A difference was observed in the pressure range where the electrical strength was kept constant. The chamber filled with helium residual gases lost its insulating properties at the highest pressure among the tested gases (2.00 × 10⁰ Pa at contact gap d = 2 mm), while the chamber filled with argon gas lost its insulating properties at the lowest pressure among the tested gases (2.00 × 10⁻¹ Pa at contact gap d = 2 mm). After a decrease in electrical strength, an intense glow discharge was observed. A theoretical description related to the initiation of an electrical breakdown in vacuum insulating systems is also presented. The situation in which the discharge chamber with a contact system was filled with the mentioned gases was analyzed. The mean free paths of the electrons and molecules as well as the velocities and energies of the electrons accelerated by the voltage applied to electrodes were calculated. The obtained results were related to the measurement parameters and analyzed in terms of the discharge development. The results of the research suggest alternatives for the further development of vacuum-extinguishing chambers used in environmentally-friendly electrical switchgear by increasing the rated operating pressure, maintaining the required electrical strength values, and thus facilitating the operation due to greater certainty in regard tomaintaining the integrity of such a vacuum interrupter. Full article

This study discusses a numerical study that was developed to optimize the ventilation system in a power substation prior to its installation. We established a multiobjective particle swarm optimizer to identify the best approach for simultaneously improving, first, the ventilation performance considering the most appropriate inlet size and outlet openings and second, the reduction of the synthetic noise of the ventilation and power consumption from the exhaust fan equipment and its operation. The study used building information modeling to construct indoor and outdoor models of the substation building and verified the overall performance using ANSYS FLUENT 18.0 software to simulate the air velocity and air temperature distribution within the building. Results show that the exhaust fan of the B1F cable finishing room and the 23 kV gas insulated switchgear (GIS) room optimize the reduction of horsepower by approximately 1 Hp and 0.5 Hp. The combined noise is reduced by 4 dBA and 2 dBA; the exhaust fan runs for 30 min, and the two equipment rooms can cool down by 2.9 °C and 1.7 °C, respectively. Therefore, it is confirmed that the MOPSO algorithm provides a more energy-efficient and environmentally friendly building ventilation environment. Full article

This paper deals with a review of the state-of-the-art performance investigations of green gas for grid (g3) gas, which is an emerging eco-friendly alternative insulation gas for sulfur hexafluoride (SF₆) that will be used in gas-insulated power facilities for reducing environmental concerns. The required physical and chemical properties of insulation gas for high-voltage applications are discussed, including dielectric strength, arc-quenching capability, heat dissipation, boiling point, vapor pressure, compatibility, and environmental and safety requirements. Current studies and results on AC, DC, and lightning impulse breakdown voltage, as well as the partial discharge of g3 gas, are provided, which indicate an equivalent dielectric strength of g3 gas with SF₆ after a proper design change or an increase in gas pressure. The switching bus-transfer current test, temperature rise test, and liquefaction temperature calculation also verify the possibility of replacing SF₆ with g3 gas. In addition, the use of g3 gas significantly reduces theabovementioned environmental concerns in terms of global warming potential and atmosphere lifetime. In recent years, g3 gas-insulated power facilities, including switchgear, transmission line, circuit breaker, and transformer, have been commercially available in the electric power industry. Full article

This paper investigates the possible options for achieving a substantial reduction in a substation footprint using air-insulated switchgear as a more environmentally-friendly alternative to gas-insulated substations that use SF₆ gas. Adopting a new approach to surge arrester location and numbers, International Electrotechnical Commission (IEC) minimum clearances can be successfully selected instead of the maximum clearances as currently adopted by many utilities, as is the case in the UK. In addition, innovative alternative compact busbar arrangements using vertical and delta configurations have been proposed by the authors. A further opportunity for compaction is offered by the application of compact and integrated technology offered from several manufacturers. The full overvoltage control within the entire substation under any surge condition is a key aspect of the feasibility of this type of substation. This work demonstrates that the new design option can be an attractive alternative for future substation configuration with minimum footprint. Full article