DFWK Cable Branch Box (Outdoor Switching Station)

Scope of Application

The DFWK-12 series outdoor ring main unit is a gas-filled outdoor ring main unit with international professional standards, developed and produced by our company using foreign professional technology, based on the characteristics of distribution networks in various regions of China and the actual situation of cableization renovation of urban distribution networks.

The DFWK-12 series outdoor ring main unit uses the HRM16-12/24 series SF6 fully sealed, fully insulated ring main switchgear. This switchgear has the advantages of modularity, expandability, full insulation, full sealing, safety, reliability, and maintenance-free operation. It is suitable for any harsh environment and is widely used in industrial parks, residential areas, streets, airports, various buildings, busy commercial centers, and other locations.

The DFWK-12 series outdoor ring main unit has standard voltage levels of 12KV and 24KV and can be expanded with distribution automation functions to achieve intelligent ring main units, making the grid stronger and smarter.

Model Meaning

Operating Conditions

• Ambient temperature: maximum +50C, minimum -40C, maximum daily average temperature not exceeding 35C;
• Relative humidity: daily average not exceeding 95%, monthly average not exceeding 90%;
• Wind speed: not exceeding 35m/s;
• Pollution class: Class III;
• Seismic intensity: 8 degrees;
• Ground inclination: not more than 3 degrees;
• Installation site: well-ventilated, free from fire, explosion, or severe vibration, and free from corrosive gases.

Special Conditions

• When the equipment is installed at an altitude above 1000 meters, it must be specially noted so that the company can adjust the SF6 pressure during manufacturing.
• If there are special harsh conditions, be sure to consult the company.

Product Features

High Safety

• All live parts are fully enclosed in the SF6 gas tank, achieving full insulation and full sealing;
• Equipped with mechanical interlocking that meets the five-prevention requirements, eliminating misoperation;
• Incoming and outgoing cables use fully insulated, fully sealed touchable connection methods, ensuring maximum personal safety;
• The cabinet is equipped with a pressure monitoring device for real-time monitoring of gas pressure during operation;
• An explosion-proof pressure relief device is installed below the gas tank, and it has passed the internal arc test by authoritative institutions.

Flexible Schemes

• Flexible incoming and outgoing methods,可以实现 left, right, and bottom incoming (outgoing);
• Flexible combination methods, arbitrary combinations between all units, unlimited expansion;
• Uses built-in busbar expansion methods, fully meeting requirements for usability, economy, and aesthetics;
• Flexible design schemes to meet user site requirements.

Compact and Reasonable Structure

• All unit modules have consistent dimensions (except for the metering module), and the compact size does not affect construction convenience.

Economy

• Maintenance-free; small footprint, high cost-effectiveness; service life exceeding 30 years.

Wide Application

• The gas tank stainless steel plates are fully automatically TIG welded by robots, achieving a protection level of IP67. It can be installed in humid, dusty, salt-laden, mining, and any air-polluted locations without special precautions.

Intelligence

• Can be supplied with electric operating devices and distribution automation terminal equipment to achieve intelligent switchgear with "four-remote" functions, meeting all requirements of smart grids for such equipment.

Applicable Product Standards

• GB 1984-2003 High-voltage AC Circuit Breakers
• GB 1985-2004 High-voltage AC Disconnectors and Earthing Switches
• GB 3804-2005 3.6KV~40.5KV High-voltage AC Load Switches (IEC60265)
• GB 16926-2009 AC Load Switch-Fuse Combination Units (IEC 60420)
• GB/T 3906-2006 3.6KV~40.5KV AC Metal-enclosed Switchgear and Controlgear (IEC 62271)
• GB/T 11002-2011 Common Technical Requirements for High-voltage Switchgear and Controlgear Standards (IEC 69271)
• GB/T11023 Test Methods for SF6 Gas Sealing of High-voltage Switchgear (IEC 60694)
• GB 4208-2008 Degrees of Protection Provided by Enclosures (IP Code) (IEC 60529)
• DL/T404 3.6KV~40.5KV AC Metal-enclosed Switchgear and Controlgear
• DL/T 4208-2008 Technical Guidelines for Ordering Outdoor High-Voltage Complete Switchgear
• Q/CSG 10020 China Southern Power Grid Urban Distribution Network Technical Guidelines
• Grid Company Material Procurement Standards - General Technical Specifications for 12KV and 24KV Ring Main Units

Main Technical Parameters

Structural Features

Main Accessories

The enclosure of the outdoor ring main unit is designed according to outdoor structural requirements. The enclosure material can be stainless steel plate, SMC, or GRC according to customer needs, with a spray-painted surface. It has sufficient mechanical strength, and the surface is sturdy and corrosion-resistant. The design is based on outdoor corrosion resistance. The enclosure material can be stainless steel plate, SMC, or GRC according to customer needs, with a spray-painted surface, providing sufficient mechanical strength. The enclosure surface has no closed detachable parts, good salt resistance. The top cover is a double-layer structure with upper and lower ventilation, and is equipped with vents for natural convection ventilation, providing good heat insulation and heat dissipation. It is rainproof and vertical. The cabinet door has a limit device after opening for easy fixing. The cabinet is equipped with a sealed bottom plate for cable entry and exit, preventing small animals and moisture from entering the cabinet. The doors on both sides of the cabinet have limit control when opened. The appearance is beautiful and grand, coordinating with the surrounding environment. The bottom plate for cable entry and exit is sealed to prevent small animals and moisture from entering the cabinet. The appearance and color of the cabinet can be customized according to user needs, and the appearance is beautiful, coordinating with the surrounding environment.

The switch unit used in the DFWK series outdoor ring main unit is the HRM16 series fully sealed, fully insulated ring main switchgear produced by our company. This switch has the advantages of modularity, unlimited free expansion, compact structure, small size, and maintenance-free operation. Description of functional units and functions:

• C Unit: Load switch unit, mainly used for cable incoming/outgoing connection, branching, sectionalizing, and control protection in 12KV and 24KV distribution networks;
• F Unit: Load switch + fuse combination unit, used for control and protection of terminal distribution transformers with a capacity of 1250KVA and below in 12KV and 24KV distribution networks;
• V Unit: Vacuum circuit breaker unit, can be used not only for cable line incoming/outgoing connection, branching, sectionalizing, control, and protection in 12KV and 24KV distribution networks, but also for control and protection of larger capacity transformers.
• D Unit: Equipped with a microcomputer relay protection device,可以实现 overcurrent protection and other functions.
• N Unit: Without switch, used for cable incoming and for connecting incoming and outgoing cables. The incoming and outgoing cables are directly connected to the busbar.
• S Unit: Metering cabinet, used for electric energy metering, can be easily combined with any other type of cabinet.

Cable Distribution Box Foundation Diagram

Ordering Information

• Product model, indoor/outdoor requirements, provide single-line diagram;
• Incoming/outgoing method;
• Number of incoming/outgoing lines, number of cable fault indicators;
• Enclosure material and color.