1 Introduction​Coastal regions face environmental challenges including heavy rainfall, lightning, high temperatures, high humidity, and high salt spray corrosion. To ensure the safety of urban distribution grids in such environments, minimize power outages caused by equipment maintenance, and prevent accidents due to equipment end-of-life and other factors affecting grid security, we have researched the use of a new type of Solid Insulated Ring Main Unit (SIRMU). This SIRMU offers long lifespan,

Introduction​Currently, SF6 gas-insulated ring main units (hereinafter referred to as "SF6 RMUs") dominate the market. However, SF6 gas is internationally recognized as one of the primary greenhouse gases. To achieve environmental protection and emissions reduction, its use must be reduced and restricted. The emergence of solid-insulated ring main units (RMUs) has addressed the issues associated with SF6 RMUs while incorporating numerous new features.​1 Ring Mains Power Supply and Ring Main Unit

1 Current Status of SF₆ Ring Main Units​1.1 Structure of Ring Main Units​Ring main units (RMUs) consist of a gas chamber, operating mechanism compartment, cable compartment, and busbar connection compartment (present in some units).The gas chamber is positioned at the rear or in locations less prone to harm personnel during internal arcing. The operating mechanism, cable, and busbar connection compartments are at the front, facilitating switch operation, cable installation, and space-efficient w

Overview​Older distribution networks are primarily radial in structure, with most incoming and outgoing lines being overhead lines. The switching equipment typically consists of air-insulated vacuum circuit breakers or minimal-oil circuit breakers. These networks suffer from frequent faults, high operating costs, and prolonged, widespread power outages in the event of a failure, significantly hindering economic development.With rapid economic growth and the implementation of urban grid renovatio

Issues and Countermeasures for 10kV SF₆ Gas-Insulated Common Tank Ring Main Unit (European-Style) Cable Connections​With the extensive use of cable lines in urban distribution networks, 10kV SF₆ gas-insulated common tank Ring Main Units (RMUs) (European-style) are widely adopted as network nodes due to their characteristics of full insulation, complete enclosure, maintenance-free operation, compact size, and flexible installation. These European-style SF₆ common tank RMUs are suitable for coasta

10kV SF₆ Ring Main Units (RMUs) Common Fault Prevention Measures​During the development of urban distribution network cabling, 10kV SF₆ Ring Main Units (RMUs) (European-style), serving as ring power supply nodes, have been widely adopted due to their features such as full insulation, complete enclosure, maintenance-free operation, compact size, and flexible, convenient installation. However, as the number of RMUs in use increases, the occurrence of faults within RMUs has also gradually risen.​1

Analysis of Two 10kV SF₆ Ring Main Unit Failures and Live Testing​​1 Introduction to 10kV SF₆ Ring Main Units​A 10kV SF₆ ring main unit (RMU) typically consists of a gas tank, an operating mechanism compartment, and a cable connection compartment.​Gas Tank: The most critical component, housing the load switch busbar, switch shaft, and SF₆ gas. The load switch is a three-position switch, including an isolating blade and an arc-extinguishing shield.​Operating Mechanism Compartment: The operating m

In-depth Solutions for Common Issues in SF6 Ring Main Units (RMUs)​​The stable operation of SF6 high-voltage RMUs is critical to grid safety. Addressing typical problems exposed during long-term operation, and based on industry practices and technical specifications, the following systematic solutions are proposed:​I. Comprehensive Gas Leakage Management Plan​​Phenomenon & Risk:​​SF6 gas leakage reduces dielectric strength (breakdown voltage drops by over 30% when pressure falls below 0.4MPa

Capacitor Operating Voltage Issue​The magnitude of a capacitor's operating voltage significantly impacts its service life and output capability, making it a key monitoring indicator in the substation busbar system. The active power loss within a capacitor primarily originates from dielectric losses and conductor resistance losses, with dielectric losses accounting for over 98%. Dielectric losses have a significant influence on the operating temperature of the capacitor. This influence can be qua

1 Post-Failure Test Diagnostic Items​​1.1 Identifying Fault Causes and Determining Test Units​Taking a rack-mounted capacitor bank as an example, each individual capacitor unit is typically equipped with an expulsion-type external fuse serving as the primary protection device. If a single capacitor experiences breakdown, parallel capacitors discharge through the fault point. The fuse and fusible element of the damaged capacitor may rupture rapidly, isolating the faulted section to ensure continu