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High Quality Ring Main Unit Components for Reliable Power Distribution
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11KV RMU Panels Indoor Medium Voltage Load Break Switches
Cotenele Electric, long recognized as a key partner of State Grid Corporation of China, offers the KDK-12D/1250-20 series 11KV RMU Panels Indoor Medium Voltage Load Break Switches as core components for both ring main units and environmentally friendly switchgear. This product has earned consistent customer praise over the years.The load break switch full compies with national and industry standards, including GB3804-2017, GB16926-2009, and GB/T1985-2023. Its main circuit features a short-time withstand current of 20kA for 4 seconds or 25kA for 3 seconds.The load break switch has features of durable and sturdy, safe and reliable, boasts a mechanical life of 3000 operations. The integrated earthing switch also demonstrates a strong short-time withstand capacity of 20kA for 4 seconds and a mechanical life of 3000 operations.
11KV Medium Voltage Indoor Earthing Switch for RMU
A earthing switch is a component in the ring main unit,which is a mechanical device used to ensure personal safety during power equipment maintenance ,Contele is one of suppliers for these switches from China,Our KDJD-12 series 11KV Medium Voltage Indoor Earthing Switch For RMU is used to effectively eliminate residual charges on the transformer side when replacing the fuse after the fuse of the composite electrical device is blown, ensuring personal safety during the replacement of the fuse.If you are purchasing grounding switches, please contact us promptly.
11KV Electrical Mechanism for Medium Voltage Switchgear
Cotenele is a China factory that manufactures the KDCM-12D/630-20 series 11KV Electrical Mechanism For Medium Voltage Switchgear, and the electric operation of the mechanism is realized by the relay contact conversion in the controller, which belongs to the economical electric operation scheme. This series of products will leave the factory after passing the full inspection Meets the requirements of relevant standards and specifications such as G8 3804-2014 "3.6kV-40.5kV High Voltage AC Load Switches".
11KV Operating Mechanism for MV Ring Main Unit
Cotenele International Trade (Wenzhou) Co., Ltd. is a professional manufacturer in China. Their KDFM-12D/630-20 series 11KV Operating Mechanism for MV Ring Main Unit features an integrated circuit board terminal design. Its electrical operation is achieved through relay contact switching within the controller, representing an economical electrical operation solution. This series of products complies with the requirements of relevant standards and specifications such as GB16926-2009 "High Voltage AC Load Switch Fuse Combination Device".
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 |
