European-style transformer cabinet
Equipment composed of high-voltage load switches
The high-voltage compartment of a European-style transformer usually consists of high-voltage load switches, high-voltage fuses, and lightning arresters, enabling power on/off operations and providing overload and short-circuit protection. The low-voltage compartment is composed of low-voltage air switches, current transformers, ammeters, voltmeters, etc. Transformers typically use S9 or dry-type types.
Equipment
Electrical components in the European-style transformer are all selected from standard products, with their technical performance meeting the corresponding standard requirements. To reliably achieve the five preventive measures, mechanical interlocks are used between electrical components. Each component is mounted on a structure with sufficient strength and rigidity for wire connections. The operation is electrically powered, no additional power supply is required; it can be connected to the TV directly.
Additionally, European-style transformers are equipped with functions for power detection, display, and measurement, and can implement corresponding protection features. They also have grounding components with clear grounding markings. Moreover, to accommodate outdoor working conditions, the shells of European-style transformers typically feature a sandwiched structure with insulating materials. The bottom of the transformer and between each compartment are equipped with cooling air inlets and outlets. They utilize natural air cooling and automatic-controlled forced air cooling in various forms to ensure proper heat dissipation of electrical equipment. They are also equipped with measures to prevent rain, dust, and the entry of small animals.
Domestically produced European-style transformers have voltage ratings: high voltage side of 3 to 35kV, low voltage side of 0.4 to 10kV. Transformer capacity: When the rated voltage ratio is 35/10, 6, or 0.4 kV, the capacity ranges from several hundred to tens of thousands of kilovolt-amperes. When the rated voltage ratio is 10 or 6/0.4 kV, the capacity ranges from several tens to several thousand kilovolt-amperes.
Application
European-style transformer substation, also known as outdoor complete transformer substation or modular transformer substation, is highly valued for its flexible modular design, ease of transportation, relocation, installation, short construction period, low operating costs, small land footprint, non-polluting, and maintenance-free features. In rural network construction (renovation), it is widely used in urban and rural 10-110kV small and medium-sized transformer (distribution) stations, industrial and mining areas, and mobile operation transformer stations. Its ease of reaching load centers, reducing the supply radius, and improving voltage quality at the end makes it particularly suitable for rural network renovation, and it is hailed as the target model for substation construction in the 21st century.
Product Features
1. Advanced technology, safe and reliable
The cabinet is made using domestic technology and processes, typically featuring galvanized aluminum zinc steel panels for the shell, and standard container materials and manufacturing techniques for the frame, ensuring excellent corrosion resistance and a 20-year rust-free guarantee. The inner panel is made of aluminum alloy clips, and the sandwich layer is insulated with fire-resistant materials. The cabinet is equipped with air conditioning and dehumidification systems, ensuring that the equipment operates unaffected by natural climate conditions and external pollution. It can function normally in extreme environments ranging from -40℃ to +40℃.
The unit within the cabinet employs domestic technical equipment such as unit vacuum switch cabinets, dry transformers, dry current transformers, vacuum circuit breakers (spring operated), etc. The product has no exposed live parts, featuring a full insulation structure that ensures zero electric shock accidents. The entire station can operate oil-free with high safety. The secondary system utilizes a microcomputer integrated automation system, enabling unattended operation.
2. High level of automation
The entire site is designed for intelligent operation, featuring a substation microcomputer integrated automation device for the protection system. These devices are installed in a decentralized manner, enabling "four remote" functions: remote measurement, remote signaling, remote control, and remote adjustment. Each unit has independent operation capabilities, comprehensive relay protection functions, and the ability to remotely set operating parameters. It also controls the humidity and temperature inside the cabinet, meeting the requirements for unattended operation.
3. Factory prefabrication
During the design phase, as long as the designers create one main circuit diagram and the design of the outdoor equipment based on the actual requirements of the substation, they can select the specifications and models of the transformer substation provided by the manufacturer. All equipment is installed and debugged at the factory, truly realizing the factory construction of substation projects, which shortens the design and manufacturing cycle. On-site installation only requires the positioning of the transformer housing, cable connections between the housing units, connection of outgoing cables, verification of protective settings, transmission tests, and other necessary adjustments. The entire substation project, from installation to commissioning, typically takes about 5 to 8 days, significantly reducing the construction timeline.
4. Flexible combination methods
European-style transformers feature a compact structure, with each unit forming an independent system. This allows for versatile combinations, such as using all enclosed transformers for 35kV and 10kV equipment, creating a fully European-style transformer substation. Alternatively, 35kV equipment can be installed outdoors, while 10kV equipment and control systems are housed indoors. This combination is particularly suitable for the renovation of existing transformer stations in rural grid upgrades, where the existing 35kV equipment remains unchanged, and only a 10kV switch box needs to be installed to achieve unattended operation.
5. Cost-effective investment with rapid ROI
European-style transformer substation (35kV equipment outdoors, 10kV equipment installed indoors) reduces investment by 40% to 50% compared to the same-scale integrated automatic substation (35kV equipment outdoors, 10kV equipment arranged in the indoor high-voltage switchgear room and control room).
6. Small land area
Equipment Installation
(1) The transformer box should be positioned as close to the load center as possible. Based on the load distribution of the area, calculate the load moment to determine the load center. Install the transformer box near the load center to shorten the power supply radius, reduce infrastructure investment, and decrease power loss by ≤12%, improve voltage quality. It is also convenient for operation and maintenance, with the low-voltage (400V) power supply radius ≤500m.
(2) The location for the transformer box must not experience intense vibrations and impacts, nor should it have a high electromagnetic induction intensity. For the underground wiring of the transformer box, the laying paths for each circuit's output should be properly arranged, ensuring a safe distance for underground facilities, and not affecting the long-term development of the power supply area.
(3) No explosive substances shall be present at the site of use, and the surrounding medium must not contain gases that corrode metals or destroy insulation, nor conductive media.
(4) The cabinet installation angle of inclination should not exceed 5°, outdoor wind speed should not exceed 35m/s, and the relative air humidity should not exceed 90% (at 25°C).
(5) No need for a control room or a corresponding workshop for the transformer installation. The 10kV equipment is non-structured, occupying a small area. On-site, only a reinforced concrete foundation is required, following the dimensions provided by the manufacturer for the transformer base.
(6) Select appropriate lifting equipment based on standard weight and relevant safety regulations; ensure the angle of the lifting wire rope is less than 60°, and use ropes to diagonally secure the box during lifting to ensure stable placement.
(7) The European style transformer is factory-set, simply connect the high and low voltage cables of the transformer to the unit.
(8) Lightning rods should be installed around the cabinet and main transformer, ensuring the equipment is within the safe protection range. Before the prefabricated foundation is laid, the grounding grid should be buried first, with its grounding resistance less than 4Ω. After the cabinet is in place, the grounding terminal of the cabinet should be securely connected.
(9) Since the European-style transformer has reached the technical requirements for unattended operation, backend equipment may not be necessary. During operation, it is important to consider enhanced anti-theft measures.
Application Scope
European-style transformers are suitable for residential communities, urban public transformers, busy city centers, construction power supply, etc. Users can choose European-style transformers according to different usage conditions and load levels.
Equipment Structure
Low-pressure rooms, transformer rooms, and high-pressure rooms are arranged in an inverted-L pattern. The European type transformer substation houses the transformer and general high-voltage electrical equipment within a single metallic enclosure, utilizing standard high-voltage load switches and fuses, as well as low-voltage switchgear, thus making the European type transformer substation larger in size.
Cabinet transformer comparison
European transformers have larger volume and lower cost, while American transformers are smaller, compact, about 1/3 to 1/5 the volume of the same capacity European transformers, with an aesthetically pleasing appearance. Although slightly more expensive, American transformers offer reliable power supply, reasonable structure, quick installation, flexibility, and ease of operation, suitable for both outdoor and indoor use.
Features of American Transformer Boxes
The difference between American-style transformers and European-style transformers lies in the American design, which unifies the transformer core, high-voltage load switches, protective fuses, and other equipment into a single oil-filled tank. It features the following characteristics:
(1) American-style transformers are compact and smaller in volume, approximately one-third the size of similarly sized European-style transformers in China. (2) American-style transformers feature a full-sealed and fully insulated structure, eliminating the need for insulation distance and ensuring reliable personal safety protection.
(3) The American-style transformer is suitable for both ring networks and terminals, offering great convenience for conversion and enhancing the reliability of power supply.
(4) High overload capacity
(5) Low wastage, S9 or SH models available.
(6) The high-voltage cable heads utilize our company's products, capable of handling 200A load current. In emergencies, they can be electrically inserted and removed as load switch operations, and they feature convenient and flexible isolation switch operation.
(7) Utilizes dual fuse protection to reduce operating costs.
(8) High ignition point oil (ignition point up to 312℃) may be used indoors.
(9) The housing features corrosion-resistant design and special coating treatment
(10) The American-style transformer is arranged in a staggered pattern. It is divided into two parts: the front section includes high and low voltage operation bays, with high and low voltage terminal connections, load switch handles, unloaded voltage regulation section switches, plug-in fuses, oil level gauges, etc.; the rear section houses the oil-filled tank and heat sinks, where the transformer windings, core, high voltage load switches, and fuses are immersed in transformer oil. The lightning arresters are also oil-immersed metal oxide types. The transformer eliminates the oil-filled pillow and is designed with a sealed oil tank using the principle of constant oil and air gap volume, with the oil tank and radiator exposed to the air, eliminating heat dissipation issues. The low voltage circuit breakers use plastic-encased circuit breakers as the main and outgoing line circuit breakers. Due to the simplified structure, the American and European-style transformers significantly reduce their footprint and volume. With their compact size and single-side door, the required footprint is only 1/4 of the European-style transformer, and the volume is only 1/5 to 1/3 of the same capacity European-style transformer.
(11) Simple protection method:
The American-style transformer employs fuses for protection on the high-voltage side and plastic-case automatic circuit breakers on the low-voltage side, mirroring the 10kV distribution transformer protection method in China. The high-voltage fuses protect against internal transformer faults, while the automatic circuit breakers safeguard the low-voltage side against overcurrent, short-circuit, and under-voltage faults.
(12) Due to the varying structures of the boxes, their applications differ, as do the power supply networks.
Due to the differing structures and reliability between American-style and European-style transformers, their applications vary. When the capacity of American-style transformers is chosen to be smaller and the area of the small community is larger, the number of transformers required increases significantly, leading to more load points on overhead lines. Reducing the load points on overhead lines necessitates an increase in the number of transformers in series, thereby weakening the network structure. To overcome the issue of a weak network structure caused by small capacity transformers, it is necessary to use a ring network solution.
(13) Different Applicable Locations - American-style Boxes are suitable for various locations.
Considering the structural features and advantages/disadvantages of American-type transformers, they are suitable for powering multi-story residential buildings and other non-critical structures with relatively lower power supply requirements. Based on our actual usage, American-type transformers, when paired with small ring main substation, are perfectly suitable for the power needs of multi-story residential buildings. Even if the transformer experiences a fault, the impact on residents is minimal, but it is not suitable for mid-rise and high-rise buildings.
Applications for European style transformers
European-style transformers are suitable for multi-story residential buildings, low-rise, high-rise, and other important structures.
Product Differentiation
American-style Transformer
1) Transformer winding connection type
Single or double 10KV incoming lines
Single transformer, typically with a capacity of 500KVA to 800KVA; 4 to 6 low-voltage outgoing cables.
2) Main components of the transformer box
Transformers, 10KV ring main switches, 10KV cable connectors, low-voltage pole top boxes, and other main components make up this product. It boasts small size, low cost, and ease of installation.
Advantages and Disadvantages of American-style Transformers
Advantages: Compact size, minimal footprint, easy to place and camouflage, and blends well with the community environment. It can shorten the length of low-voltage cables, reduce line losses, and also lower the cost of power supply accessories.
Disadvantages: Low power supply reliability; No electrical mechanism, unable to add distribution automation equipment; No capacitor installation,不利于reducing line losses; Higher noise compared to Type III and Type V stations, as Type III and Type V stations house transformers indoors, which serves as noise insulation; Additionally, the concentrated electromagnetic radiation from Type III and Type V stations is dispersed into multiple points; Due to different civil foundations for transformers of varying capacities, it is inconvenient to increase transformer capacity; When the transformer is overloaded or the user needs to increase capacity, the civil foundation needs to be rebuilt, resulting in a longer power outage period and increasing the difficulty of the project.
2. European-style Transformer Box
1) Transformer winding connection type
a. Single unit with two 10KV incoming lines
The transformer capacity per unit is generally 500KVA to 800KVA; the low-voltage outgoing cable is usually 4 to 6 circuits.
b. Two transformer configurations — two 10KV incoming lines; two transformers, each with a capacity of 500KVA to 800KVA; the low-voltage outgoing cable is typically 8 to 12 circuits.
2) Key Components of the Transformer Box
Transformers, 10KV ring main switch cabinets, low-voltage capacitors, and low-voltage switches are the main components. This is akin to compactly installing the equipment of Type III stations within a metallic enclosure, thereby miniaturizing the Type III station. The European type transformer is larger in volume and cost compared to the American type transformer.
3) Advantages: Noise levels are comparable to Type III and Type I stations; radiation is lower than that of American transformer cabinets due to the shielding effect of the transformers being housed in a metallic cabinet in European transformer cabinets; can be configured with distribution automation, offering not only the benefits of Type III and Type I stations but also the main advantages of American transformer cabinets.
4) Drawbacks: Large in size, not conducive to installation; has a certain impact on the environmental arrangement of the community.
Prospects for development
In cities and industrial grids abroad with voltage levels below 22kV, European-style transformer cabinets have been widely adopted, thereby changing the traditional method of installing transformers on poles and the spider-web-like wiring patterns. They have played a positive role in ensuring the safe and reliable operation of the power grid, reducing investment in substation construction, and accelerating construction speed, making them one of the new trends in substation equipment. Additionally, the design of the cabinet color can harmonize with the environment of use, contributing to environmental beautification. Therefore, they are bound to be widely used in our country's cities, rural areas, industrial and mining enterprises, and public buildings.
