SF6 Gas Insulated RMU
Space-Saving Power, Uncompromised Safety: Equip Your Project with Reliability.
- ODM/OEM Solutions
Tailored to Your Needs
Whether you need a new ODM SF6 Switchgear or to customize some OEM parts of our existing SF6 Gas Insulated Switchgear, we can do it for you. Here are some examples of what we can customize for you.
- Switchgear enclosure size
- Vacuum circuit-breaker
- Switch-disconnector
- Your logo
- Panel language
- Insulator
Before we start making a mold or making custom production for you, we will send you a 2D/3D drawing for your approval.
Gas Insulated RMU Parameters
| Rated voltage Ur | kV | 7.2 | 12 | 15 | 17.5 | 24 | |
|---|---|---|---|---|---|---|---|
| Rated short-duration power-frequency withstand voltage Ud | – Phase-to-phase, phase-to-earth, open contact gap | kV | 20 | 28 / 42 | 36 | 38 | 50 |
| – Across the isolating distance | kV | 23 | 32 / 48 | 39 | 45 | 60 | |
| Rated lightning impulse withstand voltage Up | – Phase-to-phase, phase-to-earth, open contact gap | kV | 60 | 75 | 95 | 95 | 125 |
| – Across the isolating distance | kV | 70 | 85 | 110 | 110 | 145 | |
| Rated frequency fr | Hz | 50 / 60 | |||||
| Rated normal current Ir | for ring-main feeders | A | 400 or 630 | ||||
| for busbar | A | 630 | |||||
| for circuit-breaker feeders | A | 250 or 630 | |||||
| for transformer feeders | A | 200 | |||||
| 50 Hz | |||||||
| – Rated short-time withstand current Ik | for switchgear with tk = 1 s | up to kA | 25 | 25 | 25 | 25 | 20/21 |
| for switchgear with tk = 3 s (design option) | up to kA | 20/21 | |||||
| – Rated peak withstand current Ip | up to kA | 63 | 63 | 63 | 63 | 50/52.5 | |
| – Rated short-circuit making current Ima | for ring-main feeders | up to kA | 63 | 63 | 63 | 63 | 50/52.5 |
| for circuit-breaker feeders | up to kA | 63 | 63 | 63 | 63 | 50/52.5 | |
| for transformer feeders | up to kA | 63 | 63 | 63 | 63 | 50/52.5 | |
| 60 Hz | |||||||
| – Rated short-time withstand current Ik | for switchgear with tk = 1 s | up to kA | 25 | 25 | 25 | 25 | 20/21 |
| or switchgear with tk = 3 s (design option) | up to kA | 20/21 | |||||
| – Rated peak withstand current Ip | up to kA | 65 | 65 | 65 | 65 | 52/55 | |
| – Rated short-circuit making current Ima | for ring-main feeders | up to kA | 65 | 65 | 65 | 65 | 52/55 |
| for circuit-breaker feeders | up to kA | 65 | 65 | 65 | 65 | 52/55 | |
| for transformer feeders | up to kA | 65 | 65 | 65 | 65 | 52/55 | |
| Filling pressure (pressure values at 20 °C) | Rated fi lling level pre (absolute) | kPa | 150 | ||||
| Minimum functional level pme (absolute) | kPa | 130 | |||||
| Ambient air temperature T 4) | |||||||
| Operation | standard | °C | –25 to +55 | ||||
| on request | °C | –40 to +70 | |||||
| Storage / transport | standard | °C | –25 to +55 | ||||
| on request | °C | –40 to +70 | |||||
| Degree of protection | for gas-fi lled switchgear vessel | IP65 | |||||
| for switchgear enclosure | IP2X / IP3X | ||||||
| for low-voltage compartment | IP3X / IP4X |
The Ultimate Guide of SF6 Gas Insulated RMU
Chapter 1
What is SF6 ring main unit?
Chapter 2
What does RMU mean in electrical?
Chapter 3
What does a ring main unit do?
Chapter 4
What is inside the ring main unit?
Chapter 5
What are the types of RMU?
Chapter 6
What are the advantages of RMU?
Chapter 7
What are the disadvantages of RMU?
Chapter 8
What is the difference between ring main unit and switchgear?
Chapter 9
Who is the manufacturer of SF6 RMU?
Chapter 1
What Is SF6 Ring Main Unit?
An SF6 Ring Main Unit (RMU) is a type of electrical switchgear that is used to manage the distribution of electrical power in a medium voltage network. It is named for its use of sulfur hexafluoride (SF6) gas as an insulating and arc quenching medium. SF6 is a highly effective insulator and interrupter in electrical applications and helps to maintain stability and efficiency in the network.
The Ring Main Unit typically consists of two or more switchgear elements, including load break switches and circuit breakers, which are interconnected in a ring configuration. This setup provides a continuous pathway for power even if one part of the network fails or is under maintenance, hence ensuring a high level of reliability and continuity of power supply.
This type of equipment is commonly used in urban distribution networks, industrial plants, and commercial buildings where space is limited and high reliability is essential. The SF6 gas in the RMU provides excellent dielectric properties that significantly enhance the device’s performance in terms of power handling and safety.
For detailed standards and specifications, SF6 RMUs are designed according to international standards such as the IEC 62271-200, which covers high-voltage switchgear and controlgear parts.
Chapter 2
What Does RMU Mean In Electrical?
RMU stands for Ring Main Unit. It’s a type of electrical distribution switchgear that is used to manage the distribution of electrical power in medium voltage networks, typically ranging from 3.3 kV to 36 kV. RMUs are compact, encapsulated, and typically used in urban power distribution networks, industrial sites, and commercial complexes where space is at a premium and reliability is critical.
A Ring Main Unit facilitates the connection and disconnection of various sections of a power grid and allows for each section of the grid to be isolated for maintenance and repair. It often includes components such as switches and circuit breakers that can switch the electrical supply to alternative or redundant paths. RMUs can be configured in several ways depending on their design and the requirements of the system, including configurations like switch-fuse combinations, circuit breaker units, and switches.
RMUs are designed to be both user-friendly and safe. They are often gas-insulated, which helps to reduce their size and enhance their reliability and durability by protecting the internal components from environmental factors.
Chapter 3
What Does A Ring Main Unit Do?
Here are some key functions and features of a Ring Main Unit:
Configuration Flexibility: RMUs can be configured in various forms such as switch-fuse combination, circuit breaker, or just switches. The typical arrangement allows each unit to connect different parts of a grid, which can be operated in a ring or radial network.
Fault Isolation: In the event of an electrical fault, the RMU can isolate the problematic section of the network without disrupting the entire system. This helps in maintaining service continuity for unaffected areas.
Safety and Reliability: RMUs are enclosed and often use SF6 gas or solid dielectric insulation to minimize the risk of electrical faults and ensure personnel safety. They are designed to withstand harsh environmental conditions and provide reliable operation.
Ease of Maintenance: RMUs are designed for minimal maintenance, thanks to their robust and sealed constructions. Some newer models also allow for remote monitoring and control, further reducing the need for physical inspections.
Compact Size: RMUs are compact, which makes them suitable for space-constrained environments. This is particularly useful in urban areas or in applications where space for electrical equipment is limited.
Integration Capability: Modern RMUs can be integrated into smart grid systems, enabling automated switching and real-time monitoring of the network’s performance. This integration enhances the overall efficiency and responsiveness of the power distribution system.
Ring Main Units are essential for efficient and reliable electrical distribution, especially in loop network configurations. They are instrumental in enhancing the operational capabilities of medium voltage networks, providing safe and continuous power supply with excellent fault management properties.
Chapter 4
What Is Inside The Ring Main Unit?
Switching Elements:
- Load Break Switches: These are used to connect or disconnect the ring system or transformers from the main supply without causing any interruption. They can safely interrupt the load current.
- Circuit Breakers: Used for automatically isolating the circuits in case of faults. These are generally SF6 or vacuum circuit breakers capable of interrupting any fault currents.
Protection and Control Devices:
- Relays: These provide necessary protection by sensing fault conditions and triggering circuit breaker operation.
- Fuses: Serve as protection against overcurrent, commonly used to protect transformers in the RMU.
- Control Panels: Include user interfaces for monitoring and controlling the RMU’s functions manually or remotely.
Busbars: These are robust conductors that serve as common connections to various outgoing and incoming circuits. They distribute power within the RMU and are designed to handle medium voltage levels.
Earth Switches: Provide a means to discharge the residual charge in the equipment for safe maintenance operations.
Instrumentation: This may include voltage and current transformers that provide inputs to metering and protective devices, ensuring accurate monitoring and control.
Gas-insulated Components: In an SF6-insulated RMU, sulfur hexafluoride gas is used as the primary insulation and arc-extinguishing medium. This type of RMU is very compact and is typically used in urban or space-constrained environments.
The RMU is designed for reliability, safety, and ease of operation and is typically used in ring networks as a point of connection between different feeders. Depending on specific customer requirements and applications, additional features such as remote operation capabilities and integration into automated network management systems might also be included.
If you have any more specific queries or need advice tailored to your particular situation, feel free to ask!
Chapter 5
What Are The Types Of RMU?
Here are the common types of RMUs:
Gas-Insulated RMU (GIS RMU): These units use sulfur hexafluoride (SF6) gas to insulate switchgear components. GIS RMUs are known for their reliability, minimal maintenance requirements, and compact size. They are suitable for environments where space is at a premium and are widely used in urban settings.
Air-Insulated RMU: As an alternative to SF6 units, air-insulated RMUs use air as the dielectric medium. These are larger and require more space compared to GIS RMUs but are environmentally friendlier and easier to maintain.
Solid Insulated RMU: These employ solid insulation material instead of SF6 gas and are an environmentally friendly alternative. They are maintenance-free and offer a good balance between compactness and environmental sustainability.
Oil-Insulated RMU: Older types of RMUs sometimes use oil as an insulating medium. While not as common today due to the environmental risks and maintenance intensity, they are still in use in certain applications.
Each type of RMU can be configured differently based on the needs of the distribution network:
- Switch-fuse combination: For protecting transformers.
- Circuit breaker units: For protection and control of the network.
- Load break switches: For making or breaking loaded circuits to manage load distribution and enable network isolation.
The choice of RMU type and configuration often depends on factors such as the application environment, space availability, environmental impact considerations, and specific operational requirements.
Chapter 6
What Are The Advantages Of RMU?
Here are some of the key advantages:
Compact Design: RMUs are designed to be compact and efficient, making them ideal for space-constrained environments. Their small footprint allows them to be installed in locations where space is at a premium, such as urban areas or inside buildings.
Safety: Safety is a top priority with RMUs. They are equipped with enclosed and sealed compartments that minimize the risk of accidental contact with live components. This feature is particularly important in public areas or places where untrained personnel might have access.
Reliability and Continuity of Service: RMUs offer excellent reliability and continuity of service. They are designed to operate under severe environmental conditions and maintain power supply by allowing for ring solutions and multiple source systems. This means that if one source fails, another can take over without disrupting the supply.
Ease of Installation and Maintenance: RMUs are generally easier to install and require less maintenance compared to traditional switchgear. Their modular design allows for easier expansion and upgrades as the network grows or changes.
Automation and Remote Control: Many RMUs come with options for automation and can be remotely monitored and controlled. This integration with smart grid technology allows operators to quickly respond to changes in the network, perform remote switching operations, and reduce the need for on-site personnel, which enhances the overall efficiency and safety of the network.
Environmental Resistance: RMUs are well-suited for various environmental conditions, including outdoor settings. They are designed to be robust and resistant to dust, water, and other environmental factors, which makes them suitable for diverse geographical areas.
Cost-Effectiveness: Although the initial investment in RMU might be higher compared to conventional switchgear, the overall lifecycle costs are lower due to reduced installation, operation, and maintenance costs.
These advantages make RMUs an excellent choice for modern electrical distribution networks, especially in urban and suburban areas where space, safety, and efficiency are critical.
Chapter 7
What Are The Disadvantages Of RMU?
RMUs are highly reliable and efficient for certain applications, but like all equipment, they have some limitations which you might want to consider:
Limited Fault Interruption Capacity: RMUs are generally designed for distribution networks with relatively lower fault levels. Their interruption capacities might not be sufficient for systems where higher fault levels are expected, compared to more robust switchgear options.
Complexity and Cost in Expansions: While RMUs offer great flexibility and compactness, expanding or reconfiguring an existing RMU setup can be complex and costly. Adding new sections or upgrading capabilities often requires significant work and investment.
Maintenance Challenges: Although RMUs are typically designed for low maintenance, they do require specialized skills for maintenance checks, especially for gas-insulated units where handling SF6 gas is involved. This can lead to higher operational costs and a need for trained personnel.
Environmental Considerations: For gas-insulated RMUs, the use of SF6, a potent greenhouse gas, poses environmental risks. Leakage of SF6 can contribute to climate change if not properly managed, and handling it requires strict precautions and adherence to environmental regulations.
Limited Visibility and Diagnostic Capability: Traditional RMUs might lack the advanced diagnostic tools that come with newer switchgear technologies. This can make it more difficult to predict failures or to quickly diagnose and rectify issues without extensive monitoring systems.
Understanding these aspects can help you make a more informed decision based on your specific needs and the characteristics of your electrical distribution system. If you have specific operational conditions or requirements, we can look into more tailored solutions that might overcome some of these disadvantages.
Chapter 8
What Is The Difference Between Ring Main Unit And Switchgear?
Both ring main units (RMUs) and switchgears are critical in the management of electrical distribution systems, but they serve different purposes and configurations.
Functionality and Configuration:
- Ring Main Unit (RMU): An RMU is a type of switchgear that is typically used in a ringed distribution network. It is compact and encapsulated, designed for unidirectional power flow with a combination of one or more load break switches and circuit breakers. RMUs can switch connections between different sources and sections of a network, which is particularly useful for ensuring continuous supply by routing power around faults. They are commonly used in compact and localized substations, especially in urban areas or where space is limited.
- Switchgear: Switchgear, on the other hand, is a broader term that includes a wide range of equipment like disconnectors, circuit breakers, and load break switches used to control, protect, and isolate electrical equipment. Switchgear can handle higher power ratings and is used in both primary and secondary distribution networks to clear faults downstream and upstream. It is essential for controlling power systems in substations and industrial applications and can be configured for radial or loop distribution systems.
Construction and Installation:
- Ring Main Unit: RMUs are usually factory-assembled and tested, designed for ease of installation and maintenance. They are often gas-insulated (commonly using SF6 gas) which allows for a more compact design and higher reliability in dense urban settings.
- Switchgear: This can be either metal-enclosed or open. It might be air-insulated or gas-insulated. Switchgear is typically larger and requires a dedicated room or outdoor space for installation. The design is robust to accommodate the high voltage and current handling capabilities.
Applications:
- RMU: Best suited for secondary distribution networks, providing redundancy and enhancing reliability. It’s particularly effective in loop network configurations.
- Switchgear: Used in both primary high voltage substations and secondary distribution points, capable of managing higher loads and more complex systems.
Safety and Maintenance:
- RMU: Due to its enclosed nature and the use of SF6 gas, it generally requires less maintenance and is considered safer for crowded urban areas.
- Switchgear: Requires regular maintenance, especially for higher voltage units. The components are more exposed, which can be a factor in larger installations.
Understanding these differences can help you choose the right equipment for your specific electrical distribution needs. If you have more detailed requirements or need advice on specific products, let us know!
Chapter 9
Who Is The Manufacturer Of SF6 RMU?
IE-Supply is the manufacturer of SF6 RMU, it mainly exports to Russia and other CIS countries. Our products are designed to meet the needs of our customers who are in high demand industries and we have customers like the State Grid Corporation of China, China Southern Power Grid, CHINT, and ABB.
IE-Supply has three production lines SF6 RMU. We understand that you have different needs than other people. That’s why we offer customization. You can give us your drawings and tell us what you want, and we’ll make it for you. As part of our customization service, we provide free 2D and 3D drawings for you to approve before we start making your order.
We are committed to delivering quality and value. Our partnerships with industry leaders demonstrate our dedication to quality and value. We guarantee on-time delivery to ensure your projects stay on track. Discover how IE-Supply can revolutionize your electrical infrastructure projects.
We Are Just A Phone Call Away.
You’ll have no problem talking to our sales team who speak Russian. They’ll understand exactly what you want and make sure you get it, which will make everything go faster and smoother.
- +86 135-8775-1570
- info@ie-supply.com