33kv Ring Main Unit

33kV Ring Main Unit for Medium-Voltage Distribution — Compact, Modular & Smart-Ready Solution

DSY Switchgear’s 33kV Ring Main Unit is a factory pre-assembled, metal-enclosed medium-voltage switchgear, engineered to deliver continuous, reliable power supply for urban grids, industrial facilities and renewable energy power distribution networks. Established in 2005, DSY Switchgear owns RMB 50.6 million registered capital and a professional technical team of 40 staff. This compact medium-voltage equipment covers rated voltages from 7.2kV to 24kV with scalable 33kV specification, featuring a maximum bus current of 1250A and 31.5kA/4s short-time withstand current. Complying with IEC 62271-200 international standards, it adopts a modular structure integrated with vacuum load switches and circuit breakers, fully adaptable to complex and demanding B2B power distribution scenarios.

What Is a 33kV Ring Main Unit?

The 33kV Ring Main Unit is a highly integrated, unit-type medium-voltage switchgear, specially developed for ring-type and radial power distribution networks. It integrates circuit breakers, load break switches and grounding switches into one sealed modular enclosure, realizing compact and efficient power distribution control.

Compared with conventional switchgear, it supports bidirectional power transmission and rapid fault isolation. When a single cable section breaks down, the rest of the power ring can maintain normal power supply, effectively improving overall power supply reliability and reducing the System Average Interruption Duration Index (SAIDI).

This equipment effectively solves three core pain points of modern power infrastructure construction: large installation space occupation of urban substations, poor tolerance to dust, salt spray and industrial pollutants in coastal and factory sites, and economic losses caused by unplanned power outages.

Key Technical Specifications

Product Features and Design AdvantagesCompact, Space-Saving Structure

Thanks to the integrated modular design, the unit can be installed in narrow spaces such as underground cable vaults and compact urban substations. Adopting SF6 insulation technology, it saves up to 70% floor space compared with traditional air-insulated switchgear, which is a key advantage for high-density urban power grid renovation and construction.

Flexible Insulation Options

We provide two optional insulation solutions: SF6 gas insulation and solid insulation. Clients can select the appropriate type according to actual site conditions, project budget and environmental certification requirements. The solid insulation version completely eliminates SF6 gas usage, perfectly matching green and low-carbon project standards.

Complete Five-Proof Mechanical Interlocking

Each device is equipped with a full set of five-proof mechanical interlocking system as standard. Optional live display devices and grounding switches are available to effectively prevent operational errors, including wrong switching operations and accidental equipment energization, ensuring on-site operation safety.

Intelligent Monitoring Ready

This switchgear supports extended configuration of fault passage indicators (FPIs) and remote FTU intelligent monitoring modules. It realizes automatic fault location, isolation and power supply restoration (FLISR), and is highly compatible with mainstream SCADA, smart grid and DMS management platforms to support intelligent grid operation.

Low Maintenance, Long Service Life

The hermetically sealed structure greatly reduces daily maintenance workload. The equipment’s designed service life reaches 30 years. The load break switch passes no less than 1,000 mechanical operation cycle tests, and the vacuum circuit breaker supports 2,000 cycle operations, ensuring stable long-term operation.

Quality Control and Standards Compliance

DSY Switchgear implements strict full-range quality inspection for every equipment before delivery to ensure stable and reliable product performance.

Partial Discharge (PD) Testing is conducted under operating voltage to verify insulation stability. Qualified products keep PD value below 5pC at 1.1× rated voltage, avoiding long-term insulation aging and equipment failure.

SF6 Leakage Rate Testing guarantees the annual gas leakage rate is lower than 0.1%, meeting environmental protection standards while maintaining stable insulation performance.

Our conventional testing items also include:

Power frequency withstand test for dielectric strength verification

Internal arc classification (IAC) AFLR testing to ensure personnel safety

CT/VT ratio calibration and protection relay accuracy testing

Mechanical operation cycle durability testing

We provide complete type test reports and professional technical drawings for each order to support your project approval and procurement filing work.

Application Scenarios

The versatile 33kV Ring Main Unit covers multiple core power distribution scenarios, delivering tailored reliable power supply solutions for different industries.

Urban Ring Network and Residential Distribution

With compact size and flexible modular loop configuration, it is highly suitable for underground power distribution networks in urban areas and residential communities, adapting to limited installation space and meeting high-standard power supply reliability requirements.

Renewable Energy Grid Connection

It serves as core collection and connection switchgear for solar and wind farm projects. It stably bears fluctuating power loads and effectively resists transient overvoltage, adapting to remote and harsh outdoor operation environments of new energy projects.

Industrial, Mining, and Heavy Manufacturing

Featuring excellent vibration resistance and compact layout, it can be deployed in underground mine tunnels and high-dust industrial substations, providing stable power support for heavy mechanical equipment without large-scale switch room construction.

Data Centers and Urban Infrastructure

It provides reliable 33kV step-down power interface for data centers and urban public infrastructure. The fully sealed structure effectively resists dust, moisture and salt air corrosion, avoiding performance degradation of traditional switchgear in harsh environments.

Customization and Supply Capabilities

DSY supports personalized equipment configuration according to customers’ one-line system diagrams. You can freely adjust the loop quantity (2–4 loops), select insulation types, add intelligent monitoring modules and customize protection relay parameters.

We provide professional OEM services for brand-customized project demands. With 20 years of manufacturing experience and more than 60 technical patents, DSY has sufficient technical strength to meet various complex project specification requirements.

Each order is equipped with complete technical documents including type test reports and drawings, together with full-lifecycle remote after-sales technical support.

Frequently Asked Questions

Q1: What are the main application scenarios of this ring main unit?

A: It is widely used in urban ring network power supply, residential power distribution, new energy grid connection and industrial terminal power distribution, supporting both ring-type and radial network operation modes.

Q2: What insulation options are available for selection?

A: We offer SF6 gas insulation and solid insulation two solutions. SF6 insulation features mature and stable long-term performance, while solid insulation is SF6-free, ideal for eco-friendly and green certification projects.

Q3: What safety protection does the five-proof interlocking system provide?

A: The standard five-proof mechanical interlock effectively prevents misoperation risks such as wrong switching sequence, accidental grounding and invalid closing. Optional live display devices further enhance visual operation safety.

Q4: Is this equipment compatible with smart grid and SCADA systems?

A: Yes. It supports RTU module integration, fault indicator configuration and remote electric operation, realizing automatic FLISR functions and perfect compatibility with smart grid and DMS platforms.

Q5: How many loops can the modular RMU configure?

A: The flexible modular design supports free combination and splicing of 2 to 4 loops, which can be flexibly adjusted according to your project’s power supply scheme and one-line diagram.

Q6: What are the advantages of 33kV RMU for long-distance power distribution?

A: Compared with low-voltage RMUs, 33kV high-voltage design reduces operating current under the same power, greatly lowering line loss and supporting longer-distance power transmission, which effectively reduces overall grid infrastructure investment.

Contact Us

If you need to customize and purchase high-performance 33kV Ring Main Unit for your medium-voltage power distribution projects, feel free to contact our professional team for targeted technical consultation and accurate project quotation. Email us at [email protected].