Product Overview
The WBC-12 ring main unit represents a fully insulated and fully sealed metal-enclosed medium-voltage switchgear assembly for 12kV/24kV distribution networks. Constructed as a compact SF6-insulated ring main unit, it integrates load break switches, vacuum switches, vacuum circuit breakers and earthing switches within a single sealed enclosure. The gas tank adopts a fully welded construction with sealed design, maintaining internal SF6 insulation under all operating conditions. Each functional unit operates independently with mechanical interlocking between load break, earthing and cable test positions. Model designation: WBC-12 [C/V/F] / [Rated Current A] – [Breaking Capacity kA], where C = Load Break Switch, V = Vacuum Switch, F = Load Break Switch-Fuse Combination. This compact ring main unit configuration serves as a standard medium-voltage distribution node across urban power networks, industrial parks and residential distribution systems.
Key Advantages
- Fully Sealed SF6 Insulation
Fully welded gas tank with sealed construction, maintaining SF6 insulation integrity throughout the product lifespan; internal components completely isolated from external environmental contamination such as condensation, pollution, high altitude, small animals and chemical substances. - Compact Modular Design
Integrated load break switch, vacuum switch, vacuum circuit breaker and earthing switch within a single enclosure, significantly reducing footprint compared to conventional air-insulated switchgear of equivalent rating. - Mechanical Interlocking
Comprehensive interlocking between load break switch, earthing switch and cable test position prevents incorrect operating sequences, ensuring operator safety during maintenance and fault handling procedures. - All-Weather Enclosure
Metal-enclosed cabinet suitable for both indoor and outdoor installation, immune to condensation, pollution, high altitude, small animals and chemical substances; ideal for high-humidity, high-dust and other harsh environmental conditions in high-voltage distribution systems.
Application Fields
- Urban Distribution Networks — ring network nodes in urban 10kV/12kV distribution systems
- Industrial Parks — primary distribution for industrial parks and factory complexes
- Residential Areas — medium-voltage distribution in residential communities and building complexes
- Commercial Districts — power distribution for shopping malls, office buildings and business centers
- Infrastructure Projects — distribution nodes for airports, stations, hospitals, electrified railways, subways, expressways and public facilities
Technical Specifications
| Item | Value |
|---|
| Rated Voltage | 12kV / 24kV |
| Power Frequency Withstand Voltage | 42kV (12kV system) / 50kV (24kV system) |
| Lightning Impulse Withstand Voltage | 95kV (12kV system) / 125kV (24kV system) |
| Rated Current | 630A (C module / V module); 1250A (CB module, vacuum circuit breaker) |
| Closed-Loop Breaking Current | 630A |
| Cable Charging Breaking Current | 135A |
| Earth Fault Breaking Current | 200A (12kV system) / 150A (24kV system) |
| Short-Circuit Breaking Current | 20kA (V module, vacuum switch) / 25kA (CB module, vacuum circuit breaker) |
| Making Capacity | 50kA (V module / earthing switch); 63kA (CB module / earthing switch); 63kA (C module, load break switch) |
| Short-Time Withstand Current (3s) | 20kA (V module / earthing switch); 25kA (CB module / earthing switch) |
| Mechanical Life | 5000 operations (C / V / CB modules and earthing switches); 3000 operations (F module, combination appliance) |
| Applicable Standards | GB/T 16926 (AC High-Voltage Load Switch-Fuse Combinations); GB 3906 (AC Metal-Enclosed Switchgear and Control Equipment for 3.6-40.5kV) |
Structure & Details
- SF6 Gas Tank
Fully welded gas tank containing SF6 insulating gas, with welded seams ensuring gas sealing and insulation integrity over the product lifespan. Internal electric field distribution is optimized for uniform performance. - Load Break Switch Unit (C Module)
SF6-insulated load break switch with rotating contact mechanism, capable of making and breaking rated load currents (630A), closed-loop currents (630A), cable charging currents (135A) and earth fault currents (200A); closing against short-circuit currents up to 63kA making capacity. - Vacuum Switch Unit (V Module)
Vacuum switch module integrated within the SF6 gas tank, providing short-circuit interruption capability up to 20kA breaking capacity with 50kA making capacity and 20kA/3s short-time withstand rating. - Vacuum Circuit Breaker Unit (CB Module)
Vacuum circuit breaker module with rated current up to 1250A, providing short-circuit interruption capability up to 25kA breaking capacity with 63kA making capacity and 25kA/3s short-time withstand rating for feeder protection applications. - Earthing Switch
Mechanically interlocked earthing switch with making capacity (50kA for V module, 63kA for CB module), enabling safe earthing of cables during maintenance procedures; interlocked with load break switch position. - Cable Compartment
Separate cable connection compartment with removable front panel, accommodating cable terminations with ample bending radius for standard medium-voltage cable installations.
Functions & Purposes
- Ring Network Switching
Load break switches enable ring network configuration and fault section isolation, allowing maintenance or fault repair without disrupting power supply to healthy network sections. - Short-Circuit Protection
Integrated vacuum switch (V module, 20kA) or vacuum circuit breaker (CB module, 25kA) interrupts short-circuit currents up to rated breaking capacity, isolating faulty feeders and preventing fault propagation through the distribution network. - Cable Earthing
Earthing switch provides a reliable grounding point for cable maintenance, with mechanical interlocking ensuring earthing is only possible when the load break switch is in the open position. - Load Current Transfer
Load break switches support on-load switching operations (630A closed-loop breaking) for network reconfiguration and load transfer between ring segments, maintaining continuous power supply during normal operations.
Ordering Information & Custom Service
- Required for Ordering: Primary circuit scheme diagram (single-line diagram); secondary wiring schematic and terminal arrangement diagram (or follow manufacturer’s standard if not provided); accessory and spare part types and quantities if required; any special requirements to be negotiated with the manufacturer.
- Customization Scope: Switch configuration (C / V / F / CB module combinations), rated current (630A / 1250A), breaking capacity (20kA / 25kA), CT/PT ratio, protection relay setting, cable entry direction and cabinet color.
- Typical Schemes Available: Incoming panel + Outgoing panel + Transformer panel configuration; Incoming panel + Metering panel configuration; custom schemes available upon request.
- Delivery Supporting Service: Factory inspection, SF6 gas density verification, installation guidance, commissioning supervision and operator training.
