10kV Environmentally Friendly Ring Main Unit: Core Application in Urban Distribution Networks
With the accelerated process of urbanization and the in-depth advancement of the global carbon neutrality strategy, urban distribution networks, as the "blood vessels" of urban energy supply, are facing increasingly stringent requirements for safety, stability, efficiency and environmental protection. The 10kV voltage level, as the core link connecting high-voltage power grids and end users, bears the important responsibility of power distribution, voltage conversion and load protection in urban areas. Among the key equipment of 10kV urban distribution networks, the 10kV environmentally friendly ring main unit (RMU) has gradually become the core equipment for urban distribution network construction and transformation due to its outstanding environmental protection performance, compact structure, high reliability and strong adaptability. It solves the pain points of traditional SF6 ring main units such as high environmental pollution, large floor space and high maintenance costs, and provides a solid technical guarantee for the green, intelligent and efficient development of urban distribution networks.
To understand why the 10kV environmentally friendly RMU can become the core of urban distribution networks, it is first necessary to clarify the special requirements of urban distribution network scenarios for power distribution equipment. Urban areas are characterized by dense population, tense land resources, high environmental protection standards and high demand for power supply reliability. Traditional urban distribution network equipment often has obvious limitations: conventional SF6 ring main units use sulfur hexafluoride (SF6) as the insulation and arc-extinguishing medium, which has an extremely high global warming potential (GWP) — its greenhouse effect is 25,200 times that of carbon dioxide, and it has a long atmospheric retention period of up to 3,200 years, which will cause serious damage to the ozone layer and the ecological environment if leaked. In addition, traditional ring main units are large in size, which is difficult to adapt to the tense land resources in urban areas, especially in old urban area transformation and high-density residential communities. At the same time, the complex maintenance process and high maintenance cost of traditional equipment also increase the operation burden of urban distribution networks.
Against this background, the 10kV environmentally friendly RMU, which takes "environmental protection, miniaturization, high reliability and low maintenance" as the core design concept, has perfectly adapted to the development needs of urban distribution networks and become the core equipment in various urban power distribution scenarios. Its unique core advantages are closely related to its optimized material selection, advanced structural design and environmentally friendly working principle, among which the innovation of insulation and arc-extinguishing medium is the key to its environmental protection performance.
The most prominent feature of the 10kV environmentally friendly RMU is its environmentally friendly insulation and arc-extinguishing system, which fundamentally solves the environmental pollution problem of traditional SF6 ring main units. At present, mainstream environmentally friendly RMUs mainly adopt two types of green alternative media: one is dry air or nitrogen (N2) mixed gas, and the other is new low-global-warming-potential (low-GWP) gases represented by perfluoroisobutyronitrile (C4F7N, referred to as C4). Unlike SF6 gas, which has high GWP and strong greenhouse effect, dry air and nitrogen are natural and non-toxic gases with zero GWP, no damage to the ozone layer, and can be directly discharged into the atmosphere without causing environmental pollution, realizing "zero carbon emission" during operation.
The new low-GWP gas C4F7N has more excellent performance: its insulation strength is 2.2 times that of SF6, and its GWP is only one-tenth of that of SF6, which not only maintains the excellent insulation and arc-extinguishing performance of traditional SF6 equipment, but also greatly reduces environmental impact. It is recognized internationally as the most potential SF6 alternative gas, and has been applied in 12kV environmentally friendly RMUs in Anhui and other regions, with stable operation for more than 4 years, fully verifying its reliability. In addition, some high-end environmentally friendly RMUs also adopt renewable and degradable natural ester insulating oil instead of traditional mineral insulating oil, which has a high ignition point (above 300℃), good thermal stability, and further improves the environmental protection and safety of the equipment. The whole equipment adopts a fully sealed structure, which can effectively prevent the leakage of insulating medium, ensure that no harmful substances are released during the whole service life, and meet the strict environmental protection standards of urban areas.
The miniaturized and compact structural design of the 10kV environmentally friendly RMU is another key advantage that makes it the core of urban distribution networks. Urban land resources are extremely tense, and power distribution equipment is often required to be installed in narrow spaces such as underground power distribution rooms, sidewalks and green belts around residential communities, which puts forward high requirements for the volume of equipment. Compared with traditional SF6 ring main units, the 10kV environmentally friendly RMU optimizes the internal structure layout, adopts integrated modular design, and integrates functions such as load switch, circuit breaker, isolating switch and measuring instrument into a small cabinet body.
Its volume is reduced by 30% to 50% compared with traditional equipment, and its weight is also significantly reduced, which not only saves floor space, reduces the difficulty of installation and transportation, but also adapts to various complex installation scenarios in urban areas. For example, in the renovation of old urban areas, where the original power distribution space is limited, the compact environmentally friendly RMU can be installed without large-scale reconstruction of the power distribution room, which greatly reduces the renovation cost and construction period. In high-density residential communities and commercial centers, the small-sized environmentally friendly RMU can be installed in the green belt or underground garage, avoiding the impact on the urban landscape and residents' living environment, and realizing the harmonious coexistence of power equipment and urban construction.
The high reliability and safety performance of the 10kV environmentally friendly RMU provides a solid guarantee for the stable operation of urban distribution networks. Urban power supply is related to the normal life of residents and the stable operation of enterprises, so the reliability of power distribution equipment is crucial. The 10kV environmentally friendly RMU adopts high-quality insulating materials and advanced manufacturing processes, with excellent insulation performance and arc-extinguishing capacity, which can effectively withstand voltage fluctuations and short-circuit faults in urban distribution networks, and ensure the continuous and stable supply of power.
At the same time, the equipment is equipped with a full range of safety protection devices, including overvoltage protection, undervoltage protection, short-circuit protection and leakage protection, which can quickly cut off the fault circuit when an abnormal situation occurs, avoid the expansion of faults and ensure the safety of equipment and personnel. In addition, the fully sealed structure of the environmentally friendly RMU can effectively prevent the entry of dust, moisture and corrosive gases, avoid equipment failure caused by environmental factors, and adapt to the harsh operating environment of urban power distribution equipment (such as high temperature, humidity and heavy pollution). The average service life of the equipment can reach 20 to 25 years, which is 5 to 10 years longer than that of traditional ring main units, greatly reducing the frequency of equipment replacement and the impact on urban power supply.
As the core equipment of urban distribution networks, the 10kV environmentally friendly RMU has a wide range of core applications, covering all key links of urban power distribution, and playing an irreplaceable role in various scenarios. The first is residential communities, especially high-density commercial residential areas. These areas have large power load density, complex load types (including household electricity, elevator electricity, lighting electricity, etc.), and high requirements for power supply reliability and environmental protection. The 10kV environmentally friendly RMU can realize the reasonable distribution of power in the community, quickly isolate fault lines, ensure that the power supply of other users is not affected when a fault occurs, and its environmentally friendly and low-noise characteristics also avoid affecting residents' living environment.
The second is urban commercial centers and central business districts (CBDs). These areas gather a large number of shopping malls, office buildings and hotels, with extremely high power demand and strict requirements for power supply stability — even a short power outage may cause huge economic losses. The 10kV environmentally friendly RMU has high reliability and fast fault handling capacity, which can ensure the continuous and stable operation of the power supply system, and its compact structure is suitable for installation in the underground power distribution rooms of commercial buildings, saving valuable ground space.
The third is the renovation of old urban areas. Old urban areas have the problems of outdated power distribution equipment, narrow power distribution space and poor environmental conditions. The 10kV environmentally friendly RMU, with its miniaturized, environmentally friendly and reliable characteristics, can perfectly replace the traditional old equipment, without large-scale reconstruction of the power distribution room, which not only improves the power supply capacity and reliability of the old urban area, but also meets the environmental protection requirements of urban renovation, helping the old urban area to realize green and intelligent power supply upgrading.
In addition, the 10kV environmentally friendly RMU also plays an important role in new urban area construction, urban industrial parks, urban renewable energy supporting systems (such as distributed photovoltaic and electric vehicle charging piles) and other scenarios. For example, in the supporting construction of urban distributed photovoltaic projects, the environmentally friendly RMU can realize the safe integration and grid connection of photovoltaic power, adapt to the intermittent and fluctuating characteristics of photovoltaic power generation, and improve the utilization rate of clean energy; in urban industrial parks, it can meet the high-power and high-reliability power demand of enterprises, and its environmental protection performance is in line with the green development concept of industrial parks.
The excellent economic and social benefits of the 10kV environmentally friendly RMU further consolidate its core position in urban distribution networks. From the economic point of view, although the initial investment cost of the 10kV environmentally friendly RMU is 20% to 30% higher than that of traditional SF6 ring main units, its long service life, low maintenance cost and energy saving effect can quickly recover the investment gap. The environmentally friendly RMU adopts a fully sealed structure, which has no need for regular replacement of insulating medium and complex maintenance work, and only needs routine inspection and dust cleaning, reducing the annual maintenance cost by 40% to 60% compared with traditional equipment.
At the same time, its miniaturized design reduces the investment in power distribution room construction and land occupation, further reducing the overall construction cost of urban distribution networks. From the social point of view, the popularization and application of 10kV environmentally friendly RMUs can effectively reduce carbon emissions and environmental pollution, help cities achieve the dual carbon goals, and improve the quality of urban ecological environment. For example, a 10kV environmentally friendly RMU using dry air as the insulating medium can reduce carbon emissions by about 100kg every year compared with a traditional SF6 RMU, and the environmental benefit is remarkable. In addition, the stable operation of the equipment can reduce power outages, improve the quality of urban power supply, and enhance the sense of happiness and security of residents.
The practical application cases of cities around the world have fully verified the core application value and excellent performance of the 10kV environmentally friendly RMU. For example, the first fully green and environmentally friendly distribution box transformer in Zhejiang Province, put into operation in Rui'an, adopts environmentally friendly gas switchgear using dry air as the medium, combined with natural ester insulating oil and modified polypropylene cables, realizing full-process environmental protection and stable operation, effectively supporting the construction of low-carbon towns. In Anqing, Anhui Province, 12kV C4 environmental protection gas RMUs have been put into grid operation on a large scale, with stable performance for more than 4 years, marking the mature application of low-GWP gas RMUs in urban distribution networks. Eaton Pingdingshan Factory has launched RVACN type environmentally friendly gas insulated RMUs (dry air RMUs), which are widely used in urban and rural power grid construction, and have been highly recognized by power grid companies.
In contrast, traditional SF6 ring main units, due to their high environmental pollution, large floor space, complex maintenance and other shortcomings, have gradually been eliminated in urban distribution network construction and transformation. Although some improved traditional RMUs have optimized some performances, they are limited by the characteristics of SF6 gas and structural design, and cannot fundamentally solve the environmental and space problems faced by urban distribution networks. Other types of power distribution equipment are either poor in reliability, large in volume, or high in cost, which are difficult to be widely applied in urban distribution networks.
In conclusion, the 10kV environmentally friendly ring main unit, with its environmentally friendly insulation and arc-extinguishing system, miniaturized compact structure, high reliability and safety, wide range of core applications, and excellent economic and social benefits, has become the core equipment of urban distribution networks. It not only solves the pain points of traditional power distribution equipment in urban scenarios, such as environmental pollution, large floor space and high maintenance cost, but also adapts to the development needs of urban greenization, intelligence and high efficiency, providing a solid technical support for the upgrading and development of urban distribution networks. With the continuous advancement of global carbon neutrality goals and the accelerating process of urbanization, the 10kV environmentally friendly RMU will be more widely popularized and applied in urban distribution networks, making greater contributions to building a green, low-carbon, safe and efficient urban energy supply system.
