Products
High Quality Ring Main Unit Components for Reliable Power Distribution
What Are Ring Main Unit Components?
Ring Main Unit components are the essential functional units that make up a complete RMU system. Their performance directly determines the safety, reliability, and stability of a medium-voltage power distribution network.A typical RMU is designed for rated voltages ranging from 3.6kV to 40.5kVand rated currents from 630A to 2500A. Depending on different application scenarios such as distribution networks, industrial loads, and commercial buildings, the configuration of Ring Main Unit components may vary accordingly.
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11KV Medium Voltage Switchgear Vacuum Circuit Breaker Isolation Switch
Cotenele is a professional China manufacturer of 11KV Medium Voltage Switchgear Vacuum Circuit Breaker Isolation Switch, specializing in 12kV–40.5kV switchgear core components. Our products are widely used in substations, renewable energy, industrial power distribution, and railway systems. These two core components of the medium-voltage ring main unit is key to building a resilient electrical infrastructure for industrial plants and modern smart grids.
11KV Medium Voltage Vacuum Circuit Breaker with Isolating Switch
The 11kV Medium Voltage Vacuum Circuit Breaker with Isolating Switch by Cotenele is a reliable and maintenance-free solution for medium-voltage power distribution systems. As a professional China switchgear manufacturer, we provide high-performance VCB units with integrated isolation function, ensuring safe operation, compact structure, and long service life. Widely used in substations, railway systems, and industrial power networks, our products support OEM/ODM customization and meet international standards.
11KV MV Vacuum Circuit Breaker with Isolator Switch
Cotenele’s KDSV-12D/630-20-S 11kV MV Vacuum Circuit Breaker with Isolator Switch is a China-made, factory-direct solution for medium-voltage switchgear. Ideal for industrial, railway, metro, and petrochemical projects, this maintenance-free, oil-free device ensures high safety, long service life, and reliable operation.
11KV Medium Voltage VCB Breaker with Isolation Mechanism
The KDSVM-12/630-20-S 11KV Medium Voltage VCB Breaker With Isolation Mechanism is a high-reliability, spring-operated operating mechanism designed for environmentally friendly switchgear. It delivers precise, rapid circuit interruption and closing, with a mechanical life exceeding 10,000 operations. Compliant with GB1984-2014 and GB/T1985-2023, it is ideal for power substations, industrial systems, renewable energy plants, and railway/metro infrastructure. Cotenele ensures factory-tested quality, OEM/ODM customization, and fast delivery for global projects.
11KV Medium Voltage Isolating Switch Disconnector
The KDSG-12D/630-20 series 11kV Medium Voltage Isolating Switch Disconnector is designed for safe isolation and reliable load switching in ring main units and gas-insulated switchgear systems. As a China manufacturer and supplier, Cotenele offers compact, maintenance-free, long-life, and stable disconnecting switches; you can choose our products with confidence.
11KV Isolating Mechanism for Medium Voltage Indoor Panels
Cotenele's KDSGM-12D/630-20 11KV Isolating Mechanism For Medium Voltage Indoor Panels
is a spring-operated three-position disconnector mechanism designed specifically for environmentally friendly GIS switchgear. Featuring five-prevention interlocks for safe disconnect and grounding operations, it ensures high reliability, maintenance-free performance, and operational safety. We are a trusted manufacturer and supplier offering fast delivery and OEM/ODM customization services for industrial, utility, and commercial power distribution projects.
Common Ring Main Unit Components
Primary Circuit Components
- Vacuum Circuit Breaker (VCB)
- Load Break Switch (LBS)
- Disconnector (Isolator)
- Earthing Switch
Protection and Measurement Components
- Current Transformer (CT)
- Voltage Transformer (VT)
- Fuses
- Surge Arrester
Control and Indication Components
- Operating Mechanism
- Interlocking System
- Voltage Presence Indicator
- Secondary Terminal Blocks
Insulation and Support Components
- Insulators
- Bushings
- Solid or Gas Insulation Structural Parts
Key Switching Devices in RMU Systems
Vacuum Circuit Breaker (VCB)
A Vacuum Circuit Breaker uses vacuum as both the insulating and arc-extinguishing medium. Its core contacts are sealed inside a vacuum interrupter. When the moving contact separates from the fixed contact, an electric arc is generated. In a vacuum environment, the arc rapidly disperses and is extinguished as the metal vapor condenses. The arc is naturally extinguished at current zero, and dielectric strength is quickly restored.
Application: VCBs are characterized by high breaking capacity, frequent operation capability, and low maintenance requirements. They are widely used in 3–10kV distribution systems for protection and control of power lines and equipment. They can interrupt both normal load current and short-circuit fault current, providing overload, short-circuit, and under-voltage protection. VCBs can be installed in both withdrawable and fixed-type switchgear.
Application: VCBs are characterized by high breaking capacity, frequent operation capability, and low maintenance requirements. They are widely used in 3–10kV distribution systems for protection and control of power lines and equipment. They can interrupt both normal load current and short-circuit fault current, providing overload, short-circuit, and under-voltage protection. VCBs can be installed in both withdrawable and fixed-type switchgear.
Load Break Switch (LBS)
A Load Break Switch is a switching device located between a disconnector and a circuit breaker. It is equipped with a simple arc-extinguishing mechanism and can make and break normal load current and overload current, but it cannot interrupt short-circuit fault current. After disconnection, a visible isolation gap is usually formed.
Application:LBS is used for switching electrical circuits under normal load conditions. Since it cannot interrupt fault currents, it is usually used together with high-voltage fuses, which provide short-circuit protection. It is widely used in 10kV and below distribution systems for transformer control.
Application:LBS is used for switching electrical circuits under normal load conditions. Since it cannot interrupt fault currents, it is usually used together with high-voltage fuses, which provide short-circuit protection. It is widely used in 10kV and below distribution systems for transformer control.
Disconnector
A disconnector has a simple structure. Its main feature is a clearly visible isolation gap after opening, ensuring that electrical equipment is safely isolated from the power source during maintenance. It has no arc-extinguishing capability and must not be operated under load conditions.
Application:It is mainly used during maintenance or inspection to ensure reliable isolation between equipment and the energized system, providing a clear and visible safety separation point.
Application:It is mainly used during maintenance or inspection to ensure reliable isolation between equipment and the energized system, providing a clear and visible safety separation point.
Switchgear Comparison
| Item | Vacuum Circuit Breaker | Load Break Switch | Disconnector |
|---|---|---|---|
| Arc-Quenching Device | Vacuum interrupter | Simple arc-extinguishing device | No arc-extinguishing capability |
| Making/Breaking Capacity | Can interrupt load and short-circuit currents | Can interrupt load current only | Cannot interrupt load current |
| Primary Purpose | Protection and control | Load switching | Isolation |
| Disconnection Visibility | No visible disconnection | Usually visible disconnection | Clear visible isolation gap |
Operating Mechanism
The operating mechanism is an essential execution unit in Ring Main Unit components, responsible for driving the opening and closing operations of main switches and earthing switches. It converts mechanical, electromagnetic, or stored spring energy into precise mechanical motion to ensure reliable switching performance.
Common Types of Operating Mechanisms
- Spring-Operated Mechanism:Most widely used type, storing energy in a spring for fast and reliable operation.
- Magnetic Mechanism:Simple structure, high reliability, and low maintenance requirements.
- Manual Mechanism:Used as backup or low-cost solution for basic distribution systems.
RMU Unit Types and Operating Mechanisms
| RMU Type | Unit Name | Main Switching Component | Operating Mechanism Type | Description |
|---|---|---|---|---|
| C-Unit | Load Break Switch Unit | Load Break Switch (LBS) | Spring-Operated Mechanism | Single spring operation; optional motorization available |
| F-Unit | LBS-Fuse Combination Unit | LBS + Fuse | Spring Mechanism with Trip Function | Dual spring system; fuse striker trip protection |
| V-Unit | Vacuum Circuit Breaker Unit | Vacuum Circuit Breaker (VCB) | Spring / Magnetic Actuator | Interrupts fault current; works with protection relays |
| D-Unit | Busbar Riser Unit | No main switch | None | Used for busbar connection between sections |
Withdrawable Switchgear vs RMU
| Item | Withdrawable Switchgear (KYN28) | Ring Main Unit (RMU) |
|---|---|---|
| Main Switching Component | Withdrawable Vacuum Circuit Breaker | Load Break Switch + Fuses or fixed VCB |
| Disconnector Function | Replaced by withdrawable truck | Integrated 3-position switch |
| Fuses | Less common | Common for transformer protection |
| Structure | Withdrawable design | Fixed compact design |
| Protection Function | Advanced protection systems | Simpler fuse-based protection |
| Size | Larger | Compact |
