Different types of SF6-FREE RMUs currently on the market

Different types of SF6-FREE RMUs currently on the market

Why we need SF6-FRE RMUs in Medium voltage area?

In high/medium voltage area, SF6 is primarily used as an insulating gas. The Global Warming Potential (GWP) of SF6 is approximately 23,500 times that of CO2, making its greenhouse effect a significant environmental concern. The Kyoto Protocol (1997), the Fluorinated Greenhouse Gases Regulation (2003), the Paris Agreement (2016), and the EU’s “Long-Term Low Emission Development Strategy” (2020) all explicitly call for limiting SF6 greenhouse gas emissions. Research on SF6 alternative gases and the development of environmentally friendly gas-insulated equipment has thus become an important and urgent task.

What is a SF6-FREE Ring Main Unit (RMU)

A SF6-free Ring Main Unit (RMU) is a type of switchgear used in medium voltage power distribution that operates without sulfur hexafluoride (SF6), a gas commonly used for its excellent insulating and arc-quenching properties but known for its high global warming potential (GWP). The development and deployment of SF6-free RMUs are driven by the need to reduce greenhouse gas emissions and adhere to environmental regulations.

What is a What is a Solid Insulated switchgear

A Solid Insulated switchgear, also known as a solid insulated ring main unit, uses solid insulating materials as the main insulating medium. It encapsulates the vacuum interrupter, its conductive connections, isolation switch, grounding switch, main busbar, branch busbar, and other primary conductive circuits with solid insulating materials. This results in one or several functional modules that are fully insulated and fully sealed, which can be recombined or expanded. The surface of the modules, which can be touched by humans, is coated with a conductive or semi-conductive shielding layer and can be directly and reliably grounded.

Advantages and Disadvantages of Solid Insulated switchgear

Compared to gas-insulated ring main units, solid insulated RMUs have their own advantages and disadvantages:

• The product is environmentally friendly. The main circuit uses solid materials for insulation, and the isolation grounding three-position switch uses solid or air insulation, resulting in no use of SF6 gas, no greenhouse gas emissions, and no ozone layer damage.
• The use of high-performance epoxy resin materials allows for a more simplified main circuit structure, achieving miniaturization and lightweight.
• Simplified operating mechanism design and product modular design reduce the number of parts, eliminate gas pressure monitoring throughout the lifecycle, reduce maintenance, and even make it maintenance-free.

What is a eco-friendly Insulated swichgear?

Eco-friendly insulated switchgear prioritize the use of eco-friendly gases, innovative structural designs, and enhanced safety features. These units aim to meet stringent environmental standards, ensuring sustainability and reliability in power distribution systems. By eliminating SF6 gas and focusing on robust construction and comprehensive safety mechanisms, these RMUs align with the future direction of sustainable and safe power infrastructure development.

Advantages of Eco-friendly insulated switchgear

Insulating Medium:

• Utilizes environmentally friendly gases such as dry air or nitrogen.
• Prohibits the use of even small amounts of SF6 gas to minimize environmental impact.

Structural Design:

• All three-position switches are arranged on the busbar side.
• The busbar side combines functionality with grounding switches.
• This design not only saves space but also enhances operational convenience.

Interlock Function:

• The combined functional grounding switch on the busbar side achieves cable-side grounding through the circuit breaker closing.
• Features mechanical and electrical interlock functions to ensure operational safety.

Shell Thickness:

• The shell thickness is required to be at least 2mm nominal thickness.
• This design ensures the robustness of the RMU and its durability in harsh environments.

Rated Parameters:

• Provides key parameters for RMUs and ring main boxes, offering detailed reference information for users.

Testing Specifications:

• Removes type testing content specific to SF6 gas-insulated RMUs.
• Places greater emphasis on environmental protection and safety.

Environmental Friendliness:

• Reduces greenhouse gas emissions.
• Complies with environmental protection requirements.
• Represents the future trend in RMU development.

In summary, the selection of ring main unit needs to be determined according to the actual power system needs and environmental protection requirements. SF6 insulated ring main unit is widely used for its excellent insulation performance and stability, but eco-friendly switchgear and solid insulated switchgear perform better in terms of environmental protection. Solid insulated ring main unit has advantages in compactness and easy maintenance.

We hope this article can help you better understand the characteristics of different insulating medium RMUs and make wise choices for the safe and stable operation of the power system.