The combination of ​Solid Insulation Assist + Dry Air Insulation​ represents the development direction for 24kV RMUs. By balancing insulation requirements with compactness and employing solid auxiliary insulation, insulation tests can be passed without significantly increasing phase-to-phase and phase-to-ground dimensions. Encapsulating the pole column solidifies the insulation for the vacuum interrupter and its connecting conductors.Maintaining the ​24kV outgoing busbar phase spacing at 110mm,

With the rapid development of the power industry, the ecological concept of low-carbon, energy-saving, and environmental protection has been deeply integrated into the design and manufacturing of power supply and distribution electrical products. The Ring Main Unit (RMU) is a key electrical device in distribution networks. Safety, environmental protection, operational reliability, energy efficiency, and economy are inevitable trends in its development. Traditional RMUs are primarily represented

Introduction:​​10kV gas-insulated RMUs are widely used due to their numerous advantages, such as being fully enclosed, possessing high insulation performance, requiring no maintenance, having a compact size, and offering flexible and convenient installation. At this stage, they have gradually become a critical node in urban distribution network ring-main power supply and play a significant role in the power distribution system. Problems within gas-insulated RMUs can severely impact the entire di

Ⅰ. Technical Bottlenecks of SF₆ Substitution​​Insulation Medium Performance Gap​o Dried Air/N₂ insulation strength is only 1/3 of SF₆, requiring expansion of contact gap from 60mm to ≥150mm.o Conventional spring mechanisms lack energy to drive rapid closure of large gaps, easily causing contact ablation due to pre-strike.o Synthetic gases (e.g., C4+CO₂) decompose under arcing, leading to irreversible insulation degradation.​Mechanical Structural Limitations​o National Grid standardization fix

According to insulation type, ring main units (RMUs) can be categorized as gas-insulated or air-insulated. The former installs primary circuit components in a sealed metal enclosure filled with low-pressure gas (primarily SF₆ or mixed gases) as the insulating medium, using cable terminals for incoming and outgoing lines. Due to superior insulation, compact size, and modular design, they are widely used in 10kV outdoor distribution substations and prefabricated transformer stations. However, thei

Ⅰ. Problem Context​As a core component in urban power distribution networks, ring main units (RMUs) are widely used in residential areas, factories, and public buildings due to their compact structure, low cost, and high reliability. However, internal equipment failures or arc faults may generate high-temperature, high-pressure gas, leading to cabinet explosions that endanger personnel and equipment. While traditional sealed designs maintain insulation integrity, they fail to rapidly release sud

1 Introduction​Common insulation methods for 10kV medium-voltage ring main units (RMUs) include gas insulation, solid insulation, and air insulation.• Gas insulation typically uses SF₆ as the insulating medium. However, a single SF₆ molecule has a greenhouse effect 25,000 times greater than a CO₂ molecule, and SF₆ persists in the atmosphere for 3,400 years, posing significant environmental risks. Medium-voltage RMUs are widely distributed, making SF₆ recovery difficult and costly if handled

With the development of urban power grids, the number of solid-insulated ring main unit (RMU) installations has continuously increased. Their operational status significantly impacts the power supply reliability of the electrical system. The consequences of failures are severe: direct damage includes damage to the protected lines and equipment, as well as power loss; indirect consequences cause widespread customer outages, disrupting daily life, production, and even social stability.Currently, t

The solid insulated ring main unit (RMU) is a novel distribution equipment that integrates external solid encapsulation, insulated busbar, and compact combined unit technology. Its switches and high-voltage live components are entirely embedded in epoxy resin, which serves as the primary insulation between live parts and ground, and between phases. As an environmentally friendly alternative to SF₆ gas-insulated equipment, the 12kV solid insulated RMU offers advantages but inherently suffers from

"Economy" remains paramount in power equipment procurement decisions.​​ When it comes to Solid Insulated Ring Main Units (SIRMUs), the seemingly higher initial price often causes concern. However, a deeper analysis of their Life Cycle Cost (LCC) reveals a surprisingly compelling economic picture – it emerges as the wiser and ultimately more cost-effective choice.​Initial Investment: A Misunderstood Starting Point​Admittedly, the purchase price of a SIRMU can be about 5%-15% higher than tra