With the continuous upgrading of urban power grids, new energy power generation and industrial power supply systems, compact, intelligent and low-maintenance medium voltage switchgear has become an indispensable core equipment for power distribution engineering. The Ring Main Unit With Circuit Breaker, represented by XGN15 series SF6 air-insulated ring main unit, has gradually replaced traditional bulky switchgear due to its small footprint, stable performance and strong scalability. This blog takes the products manufactured by Zhejiang Usune Electric Co., Ltd. as the core, comprehensively introduces product features, complete technical parameters, internal structure, operating specifications, application scenarios and supporting services.
The Ring Main Unit With Circuit Breakeris a metal-enclosed modular switchgear specially developed for 12kV to 36kV medium voltage power distribution systems. Adopting advanced SF6 sulfur hexafluoride load switch and air insulation technology, it integrates circuit breaking, protection, monitoring and interlocking functions into one cabinet. Developed and produced independently by Zhejiang Usune Electric Co., Ltd., the XGN15 series product features compact layout, flexible operation and reliable mechanical interlock.
Different from conventional switch cabinets, this ring main unit is designed for power distribution automation. It greatly reduces the difficulty of on-site construction and later maintenance, and is suitable for various narrow installation spaces. Supported by the company’s complete R&D, production and testing system, every production link strictly complies with international standards, ensuring long-term stable operation of products in complex power distribution environments. It has been widely promoted in urban and rural power grid renovation, industrial and civil power supply, new energy and other fields at home and abroad.
The Ring Main Unit With Circuit Breaker stands out in the medium voltage switchgear market with multiple core strengths. Combined with independent R&D technology and optimized design, its main advantages are summarized as follows:
•Diversified Main Switch Configuration: Equipped with self-produced SF6 load switch as standard, which has long service life, stable operation and low maintenance cost. Users can also choose to install vacuum circuit breakers to improve breaking capacity and safety protection level, adapting to different power distribution demands.
•Dual Operation & Intelligent Upgrade: Support both manual and electric operation modes to meet diverse on-site operation habits. It can be matched with FTU and RTU devices to realize remote control, remote signaling, remote measurement and remote adjustment, fully meeting the "four remote" requirements of distribution automation and realizing intelligent grid management.
•Advanced Monitoring & Protection Technology: Built-in high-precision sensors and protection relays, which can monitor the equipment operating status in real time, quickly respond to faults and effectively protect the safety of power distribution systems and operators.
•Lightweight & Expandable Structure: Adopts optimized assembly scheme, which is convenient for transportation, hoisting and installation. The modular design supports free combination and later capacity expansion, flexibly coping with the changing power demand of the market.
•High Safety & Compact Size: Air insulation structure + reliable mechanical interlock device, effectively preventing misoperation. The small cabinet size saves floor space, which is the preferred equipment for substations and distribution rooms with limited space.
To ensure the stable and safe operation of the Ring Main Unit With Circuit Breaker, the equipment has clear requirements for the operating environment. All products are tested in accordance with the following standards:
1.Maximum altitude: ≤1000m
2.Ambient temperature range: -35℃ ~ 45℃, the maximum temperature difference shall not exceed 25℃
3.Humidity standard: Average daily relative humidity ≤95%; Average monthly relative humidity ≤90%
4.Seismic resistance: Adapt to seismic intensity of 8 degrees and below
5.Site requirements: No severe vibration, impact, open fire, chemical corrosion and explosion hazards
Please confirm the on-site environment before installation to extend the service life of the equipment and avoid operational failures.
The following table lists all standard technical parameters of the XGN15 series Ring Main Unit With Circuit Breaker, covering 12kV, 24kV and 36kV three mainstream voltage levels, for your procurement and engineering design reference:
| S/N | Name | Unit | 12kV | 24kV | 36kV |
| 1 | Rated voltage | kV | 12 | 24 | 36 |
| 2 | Rated current | A | 630 | 630 | 630 |
| 3 | Rated closed loop breaking current | A | 630 | 630 | 630 |
| 4 | Rated on load breaking current | A | 630 | 630 | 630 |
| 5 | Rated short time withstand current | kA | 16 | 16 | 16 |
| 6 | Rated peak withstand current | kA | 40 | 40 | 40 |
| 7 | Rated short-circuit making current | kA | 40 | 40 | 40 |
| 8 | Rated power frequency withstand voltage (Phase-to-phase & phase-to-earth) | kV | 28 | 50 | 70 |
| 9 | Rated power frequency withstand voltage (Across isolating distance) | kV | 32 | 60 | 80 |
| 10 | Rated lightning withstand voltage (Phase-to-phase & phase-to-earth) | kV | 75 | 125 | 170 |
| 11 | Rated lightning withstand voltage (Across isolating distance) | kV | 85 | 145 | 195 |
| 12 | Rated transfer current | A | 630 | 630 | 630 |
| 13 | Mechanical endurance | ops | M1 1000 | M1 1000 | M1 1000 |
| 14 | Electrical endurance | ops | E1 | E1 | E1 |
| 15 | SF6 gas pressure (20℃) | bar | 0.5 | 0.5 | 0.5 |
| 16 | Yearly leakage rate | ≤% | 0.5 | 0.5 | 0.5 |
| 17 | Enclosure protection degree | / | IP3X | IP3X | IP3X |
The Ring Main Unit With Circuit Breaker supports multiple cabinet types and flexible component configuration. Different cabinet bodies have corresponding size standards for 12kV, 24kV and 36kV systems, as shown in the table below:
| No. | Switchgear Type | Optional Configuration | 12kV Dimensions (W×D×H, mm) | 24kV Dimensions (W×D×H, mm) | 36kV Dimensions (W×D×H, mm) |
| 1 | Incoming/Outgoing LBS Panel | Load switch, Earthing switch, Main busbar | 375×1000×1635; 500×1000×1885 | 375×1000×1635; 600×1200×2000 | 750×1400×2250; 900×1600×2300 |
| 2 | Transformer Protection Panel | Load switch, Earthing switch, Fuse, Main busbar | 375×1000×1635; 500×1000×1885 | 375×1000×1635; 600×1200×2000 | 750×1400×2250; 900×1600×2300 |
| 3 | Metering Panel | Transformer, Fuse, Main busbar | 500×1000×1635 | 750×1000×1635 | 750×1400×2250 |
| 4 | CB Outgoing Panel | Breaker, Current transformer, Load switch, Earthing switch, Relay protection, Main busbar | 500×1000×1635; 750×1000×1635 | 750×1000×1885; 800×1200×2200 | 1000×1400×2250 |
| 5 | CB Outgoing with Metering Panel | Breaker, Current transformer, Transformer, Load switch, Earthing switch, Relay protection, Main busbar | 750×1000×1635 | 750×1000×1885 | 1000×1400×2250 |
6.1 Overall Cabinet Structure
The cabinet of Ring Main Unit With Circuit Breaker is divided into upper and lower independent units, with clear partition and strong safety:
1.Busbar room: Located at the upper part of the cabinet, the main busbar runs through the entire switchgear group to realize power transmission between cabinets.
2.Main switch room: Equipped with epoxy resin encapsulated SF6 load switch, with an observation hole and optional SF6 gas density meter.
3.Cable room: Spacious space for cable wiring, which can be equipped with lightning arrester, current transformer and other accessories. The bottom plate and cabinet door are detachable for easy cable installation.
4.Operating mechanism & low voltage control room: Equipped with mechanical interlock, position indicator, auxiliary contacts, trip coil and other components, supporting various control loops and measuring instruments.
The XGN15 V module ring main unit is composed of vacuum circuit breaker, SF6 circuit breaker, interlock mechanism and earthing switch. The installation methods are front fixed and lateral fixed. The circuit breaker and load switch can be interlocked to prevent misoperation.
6.2 Two Types of Operating Mechanisms
•Type K (Double-function single-spring mechanism): The load switch is operated by lever or motor independently; the earthing switch is driven by compression spring and operated by a separate lever.
•Type A (Double-function double-spring mechanism): The load switch adopts spring energy storage, supporting lever, motor or button tripping. The earthing switch is operated by an independent lever with spring drive.
All operations of the Ring Main Unit With Circuit Breaker must be carried out with the cabinet door closed. Operators need to follow the standardized process:
7.1 Power On Operation
1.Confirm the cabinet door is fully closed, insert the operating handle into the upper hole and rotate 180° counterclockwise until the brake separating sound is heard, and the earthing switch is disconnected.
2.Insert the handle into the lower hole and rotate 180° clockwise until the closing sound is heard. The indicator is in the working position, and the power-on operation is completed.
7.2 Power Off Operation
1.Insert the handle into the lower hole and rotate 180° counterclockwise to cut off the power; if equipped with a button, directly press the trip button.
2.Check that the live display is completely extinguished to confirm the cable room is powerless. Insert the handle into the upper hole and rotate 180° clockwise to close the earthing switch. The cabinet door is unlocked, and the power-off operation is completed.
Note: Check the SF6 pressure gauge before each switching operation to ensure the equipment works within the normal pressure range.
8.1 Transportation & Storage
•When the cabinet is fixed on the bottom plate, it can be transported by forklift; otherwise, use integral hoisting. The equipment must be kept vertical during transportation and shall not be overturned.
•The switchgear shall not be stored outdoors for a long time to avoid damp, dust and corrosion.
8.2 Maintenance Rules
1.The equipment is maintenance-free within 3 years under normal operating conditions, and the spring operating mechanism does not need lubrication.
2.The regular maintenance cycle is 1 year. Maintenance contents include tightening all electrical connectors, vacuuming and inspecting internal components.
3.Conduct closing and opening tests for all switches and earthing switches regularly, and test the electrical loop to ensure flexible operation.
4.Inspect and debug relay protection devices before putting into operation.
9.1 Attached Documents & Accessories
Each set of Ring Main Unit With Circuit Breaker is delivered with complete materials: Product certificate, operation manual, engineering design drawings and one set of special operating handle.
9.2 Order Information Required
Customers need to provide the following information when placing orders: Main circuit wiring diagram, switchgear installation plan, component model, auxiliary loop schematic and other special technical requirements, so as to ensure the products are customized accurately.
Zhejiang Usune Electric Co., Ltd. was founded in 2011 and located in Yueqing Economic Development Zone, a famous electrical production base in China. The company has a registered capital of 8 million US dollars, a 4300㎡ modern production workshop and more than 100 professional employees. After years of development, it has built three core production lines: low & medium voltage switchgear production line, high voltage circuit breaker production line and epoxy resin injection production line.
The company integrates R&D, production and sales, with a complete product matrix covering high and low voltage switchgear, transformers, mutual inductors, high voltage circuit breakers and switch accessories. It has passed ISO 9001, ISO 14001 and ISO 45001 certifications, and has become a qualified supplier of State Grid Corporation of China and China Railway Construction Corporation. With more than 14 years of industry experience, the company has an experienced R&D team and strict QC system, supporting OEM customization. The conventional production cycle is controlled within 15-20 days, and all products are equipped with complete test reports to guarantee reliable quality.
The Ring Main Unit With Circuit Breaker has been applied in many key projects at home and abroad, accumulating rich engineering experience:
•Aerospace launch projects
•Huaneng Group chemical plant and power station projects
•Nuclear power plants, hydropower stations and oil storage centers
•Urban residential communities, commercial complexes and scenic spot supporting power distribution
•318 National Highway, railways, tunnels and other transportation power supply projects
Stable product performance and thoughtful after-sales service have won unanimous praise from engineering contractors and end users.
Q1: Are you a manufacturer or trading company?
A: We are a professional direct factory. All Ring Main Unit With Circuit Breaker and other electrical products are independently produced, with competitive factory direct prices.
Q2: How long can I get the quotation after sending inquiry?
A: Our sales team will provide a formal quotation within 24 hours after receiving your detailed demand.
Q3: Can we customize the logo and appearance of the products?
A: Yes, we support OEM and ODM services, and can print customer logos and company information on the cabinet as required.
Q4: What is the standard production lead time?
A: The delivery time is determined by the order quantity. Normally, the goods can be delivered within 15-20 days after receiving the deposit.
Q5: What is your quality control process?
A: We implement full-process inspection from raw materials, accessories to finished products. All equipment will undergo routine factory tests before delivery, with multiple test reports provided.
Q6: How to solve product quality problems after sales?
A: If any quality problem occurs, please send photos or videos to us. Our technical team will put forward a targeted solution within 1-3 days.
Q7: What is the product warranty period?
A: We provide a 12-month warranty service starting from the delivery date.
Q8: Why choose us as your supplier?
A: We have 14+ years of professional experience, strong R&D and customization capabilities, strict quality control, stable delivery cycle and complete test reports, providing one-stop power distribution equipment solutions.
As a core equipment for modern medium voltage ring network power supply, the Ring Main Unit With Circuit Breaker integrates compact structure, intelligent function, low maintenance and high safety, which perfectly adapts to the development trend of urban smart grid, new energy power generation and industrial power distribution. Supported by strong R&D strength, standardized production lines and perfect quality control system, Zhejiang Usune Electric Co., Ltd. provides high-quality, customizable ring main units and a full set of supporting services for global customers.
Whether you are engaged in power engineering contracting, electrical equipment wholesale, new energy project construction or urban grid renovation, our products can meet your diverse procurement and engineering needs. If you want to know more about product parameters, customized schemes, quotation and project cooperation details, please feel free to contact us. Our professional international sales and technical team will reply to you in a timely manner, provide free sample support and professional technical guidance, and look forward to establishing long-term win-win cooperative relations with partners all over the world.
