چی دەری خۆشەوە ڕاستەوخۆییەکەی بەرزترین بەڵگەبێیە بۆ گازی SF₆ لە Unit-های مەینی Ring

1. Hêla û SF₆ Gas-insulated Ring Main Units

Hêla ring main units di navbera ku bişeyên load break switches, disconnectors, an pêşketina her du derbas da ku bi taybetmendiyên grounding hene, ji bo seroperîna xwe ya ber or ên elektrik biceribin. Li virûsîna wan, SF₆ gas-insulated ring main units, ku çalakiya li ser gas-insulated switchgear hatine dixebitand, bi karîna SF₆ gas ji bo insulation û arc quenching bikar înin, lêkevin dikare ya wateyekan, guhertina nivîsandin, nasazî û stabilitiyekî chemîkîyek hejmartî, ku wekî mediumek baxtî e.

2. Sebebên Biguherîna SF₆ Gas bi Dry Air

Hêliya SF₆ gas bi rastî taybetmendiyên zorî hene, ji bo ku potentialiye global warming (GWP) ya wateyekan girîng e, ku wekî yekan ji şeş greenhouse gases ku ji aliyê Kyoto Protocol re bandor kirin. Ji bo ku China wekî yek signatory ku tevgerî dike ku jêrbarîne bike, ji sal 2005 ta sal 2019 carbon intensity-ya wata ji 48.1% biguherînin, target-a 2020-a wekî piştguh biafirandin. Bi mînavî ku objektîf-a nasyonal a peaking carbon emissions paşîn 2030 û achieving carbon neutrality paşîn 2060 be, reducing carbon emissions taniyê tiştî ye di cihê power planning de. Di vê axoyê de, biguherîna SF₆ gas bi dry air di medium voltage switchgear de bi pêvekên penj serebî re:

2.1 Zero GWP of Dry Air

Indeksi GWP dike nimîne ku çendîk birra wateyek greenhouse gas dike ku were bi global warming re hesabandin ji bo ku birra wateyek carbon dioxide di demekî belaş de. GWP-a SF₆ 23,900 jêr CO₂ e, ku wekî yekan ji şeş gases ku ji aliyê Kyoto Protocol û European Directive 2003/87 re bandor kirin, ji bo impact-a environmentî ya wateyekan. Compartment-i average load switch an circuit breaker pirsa 1 kg SF₆ hene; ji bo ku werî, vê amariya bi driving a car approximately 200,000 km re were hesabandin ji bo environmental damage.

Bi bîyanî ku hêlê 30 million switchgear units di navbera jihan de hene, pirsa bihêvişî e ku alternative bi SF₆ re biguhezînin. Bi GWP-a zero, dry air—ku 21% oxygen û 79% nitrogen hate—solutionek da dike ku concerns over global warming contributions jê bide, ku wekî substitute ideal bi SF₆ re dike, ji bo environmental safety û benefits-a wateyekan. A comparison between SF₆ and dry air properties is summarized in Table 1.

2.2 Dry Air Requires No Recovery or Disposal

Gas-insulated metal-enclosed switchgear-i environmentally friendly nekarîn SF₆ gas di seroperîna xwe ya production û assembly de bikar bînin, ku need for gas recovery û protection systems jê bide. Li virûsîna wan, SF₆ gas switchgear divê SF₆ gas li ser closed system de hêle bike throughout its entire lifecycle to minimize leakage û reduce environmental impact.

Ji bo maintenance, gas recovery units bikar înin ji bo collect the gas on-site. Ji bo purification û remove impurities, gas reused bike. Lê, under switching operations, SF₆ can produce toxic by-products, used SF₆ gas as hazardous waste classify bike. The cost of disposing of SF₆ gas is substantial, approximately 20% of the equipment's original price. Using dry air completely eliminates the need for SF₆, significantly reducing the environmental impact of switchgear û avoiding the costs û procedures associated with disposal û recovery.

2.3 Dry Air Offers Additional Advantages for Operators

New SF₆-free switchgear using dry air provides numerous benefits for operators: ① It retains the compact size that traditional SF₆ equipment is valued for, and the operation method remains unchanged, so technicians require no additional training; ② The three-position load switch in environmentally friendly gas-insulated switchgear uses parallel vacuum interruption technology, maintaining the original three-position operation habits while enabling combined appliance solutions, offering customers economical and reliable transformer protection.

2.4 Dry Air Protects Personnel Health and Safety

Medium-voltage switchgear is often used in public areas, so health and safety are primary considerations when selecting an SF₆ alternative. Dry air, as a safe substitute, protects the public from potential health and safety risks. It is completely non-toxic, so even in the event of a leak, it poses no harm to people or the environment. It does not present health risks to personnel responsible for installation and decommissioning, and there is no need to establish strict equipment handling regulations for personnel safety. In contrast, unverified proprietary gases may pose health and safety risks.

2.5 Dry Air Alleviates Regulatory Concerns

Many companies are taking significant steps to drastically reduce greenhouse gas emissions. These strategic efforts are driven not only by a desire for greater sustainability but also by strong regulatory pressures. In Europe, the use, handling, decommissioning, monitoring, and inventory record-keeping of SF₆ gas are strictly regulated. In China, relevant policies and measures have been introduced since 2012 to regulate the use and recovery of SF₆ gas. According to standards issued by the Standardization Administration of China, SF₆ gas emissions generated during the maintenance and decommissioning of SF₆ equipment have been included in the greenhouse gas accounting and reporting scope for Chinese power grid enterprises.

Given the expectation of increasingly stringent future regulations, adopting environmentally friendly alternative products that are not subject to future regulatory constraints is a prudent choice to ensure operational continuity. Dry air medium-voltage switchgear provides reliable insulation and interruption performance without being affected by environmental regulations or carbon taxes. As the world's second-largest economy and largest energy consumer, China plays a pivotal role in the global energy transition. Recently, the Fifth Plenary Session of the 19th Central Committee proposed key socio-economic development goals for China's 14th Five-Year Plan period, explicitly stating that "energy resource allocation should become more rational, utilization efficiency should significantly improve, and total emissions of major pollutants should continue to decrease."

In summary, dry air as an insulating medium offers the following advantages: ① environmentally friendly and green; ② good thermal conductivity; ③ no need for ventilation or protective equipment during equipment production and maintenance; ④ metal particles generated during production or use pose minimal hazard to dry air-insulated switchgear.

3 Conclusion

The new type of ring main unit uses dry air as an insulating medium, replacing the environmentally harmful SF₆ gas, thereby reducing greenhouse gas emissions. At the end of its life cycle, over 90% of the materials can be recycled. Employing a slight positive pressure gas insulation method reduces the possibility of gas leakage, enhancing safety and reliability. High-voltage components are completely sealed within a metal enclosure, ensuring safe operation in harsh environments such as high altitudes, severe cold, humidity, and pollution. Vacuum switches and three-position isolation/grounding switches support both manual and electric operation, and the switchgear features intelligent capabilities.

Although environmentally friendly ring main units have made progress in intelligence, greenness, and environmental protection, the insulating performance of nitrogen and dry air under the same pressure is only about one-third that of SF₆, particularly in high-voltage GIS products, where no viable replacement for SF₆ has yet been found. Therefore, further efforts are needed in the development of environmentally friendly gases.