European-style transformer cabinet
Equipment composed of high-voltage load switches
The high-voltage compartment of an European-style transformer is typically composed of high-voltage load switches, high-voltage fuses, and lightning arresters, allowing for power on/off operations and providing over-load and short-circuit protection. The low-voltage compartment consists of low-voltage air switches, current transformers, ammeters, voltmeters, etc. Transformers usually adopt the S9 type or dry-type.
Equipment
Electrical components in the European-style transformer are all selected from standardized products, with technical performance meeting the corresponding standards. To reliably achieve the five-protection requirements, mechanical interlocks are used between electrical components. Each component is mounted on a structure with sufficient strength and rigidity for wire connections. Operation is by electric means, no additional power supply is required; it can be derived from the TV.
Additionally, European-style transformers are equipped with functions for electrical power detection, display, and measurement, and can achieve corresponding protection functions. They also have grounding components with clear grounding markings. Moreover, to accommodate outdoor working conditions, the tops of European-style transformers typically feature a sandwich structure with insulating material, and the bottom of the cabinet and between compartments are equipped with cooling air inlets and outlets. They utilize various methods such as natural air cooling and automatically controlled forced air cooling 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: the high voltage side is 3 to 35kV, and the low voltage side is 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 kVA. When the rated voltage ratio is 10 or 6/0.4 kV, the capacity ranges from several tens to several thousand kVA.
Application
European-style transformers, also known as outdoor integrated substation sets or modular substation sets, are highly valued for their flexible modular design, ease of transportation, relocation, installation, short construction period, low operational costs, small land footprint, zero pollution, and maintenance-free features. They are extensively used in the construction and renovation of urban and rural 10-110kV small and medium-sized transformer substations, industrial and mining sites, and mobile power stations for construction work. Their ability to penetrate deep into load centers, reduce power supply radii, and improve voltage quality at the end-users' end makes them particularly suitable for rural grid renovations and has earned them the reputation as the target model for substation construction in the 21st century.
Product Features
1. Advanced technology, safe and reliable
The housing section utilizes domestic technology and processes, typically made of galvanized aluminum zinc steel plates for the outer shell, with frames crafted from standard container materials and techniques, offering excellent corrosion resistance, guaranteed to prevent rust for 20 years. The interior lining is made of aluminum alloy panels, and the sandwich layer is insulated with fire-resistant materials. Air conditioning and dehumidification systems are installed inside the container, ensuring the equipment operates unaffected by natural climate conditions and external pollution. It is designed to function normally in extreme environments ranging from -40°C to +40°C.
The unit within the box employs domestic technical equipment such as unit vacuum switch cabinets, dry-type transformers, dry-type current transformers, vacuum circuit breakers (spring-actuated mechanism), etc. The product has no exposed live parts and features a full insulation structure, ensuring zero electric shock incidents. The entire station can operate oil-free, with high safety levels. The secondary system utilizes a microcomputer-based comprehensive automation system, allowing for unattended operation.
High level of automation
Fully intelligent site design; the protection system utilizes a substation microcomputer comprehensive automation device, installed in a decentralized manner, enabling "four remote" functions—remote measurement, remote signaling, remote control, and remote adjustment. Each unit features independent operation capabilities, comprehensive relay protection functions, allows for remote setting of operating parameters, and controls the humidity and temperature inside the enclosure, meeting requirements for unattended operation.
3. Factory Prefabrication
During design, once the designers create a main wiring 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 in one go at the factory, truly realizing the industrialization of substation construction and shortening the design and manufacturing cycle. On-site installation only requires the positioning of the cabinets, cable connections between the cabinets, connection of outgoing cables, verification of protective settings, transmission tests, and other necessary adjustments. The entire substation, from installation to operation, typically takes only about 5 to 8 days, significantly reducing the construction timeline.
4. Flexible combination methods
European-style transformers feature a compact structure, with each box forming an independent system. This allows for versatile combinations, such as using all enclosed boxes to install 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 configuration is particularly suitable for the renovation of existing transformer stations in rural network upgrades, where the existing 35kV equipment remains unchanged, and only the installation of a 10kV switch box is required to achieve unattended operation.
5. Cost-effective investment with rapid returns
European-style transformer substation (35kV equipment outdoor, 10kV equipment indoor installation) reduces investment by 40% to 50% compared to the same-scale comprehensive automation substation (35kV equipment outdoor, 10kV equipment in indoor high-voltage switchgear room and control room).
6. Compact land area
Equipment Installation
(1) The transformer position should be close to the load center. Calculate the load moment based on the load distribution of the area, determine the load center, and install the transformer near it. This can shorten the power supply radius, reduce infrastructure investment, and decrease power loss by ≤12%, improve voltage quality, facilitate operation and maintenance, and its low-voltage (400V) power supply radius is ≤500m.
(2) The location for the transformer box must not experience intense vibration or impact, nor should it have high electromagnetic induction strength. For the buried cable lines of the transformer box, proper layout of the wiring paths for each circuit should be arranged, ensuring a safe distance from underground facilities, and not affecting the long-term development of the power supply area.
(3) No explosive substances are allowed in the areas of use, and the surrounding medium must not contain corrosive gases and conductive media that can damage insulation.
(4) The cabinet installation should not exceed a vertical tilt angle of 5°, outdoor wind speed should not exceed 35m/s, and relative air humidity should not exceed 90% (at 25°C).
(5) The installation of the transformer cabinet does not require the construction of a control room and corresponding factory building. The 10kV equipment is non-structured, occupying a small area of land. On-site, only a reinforced concrete foundation is needed, following the base dimensions provided by the manufacturer.
(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 a stable placement.
(7) The European-style transformer is factory-tested and ready for use; simply connect the high-voltage and low-voltage cables to the transformer box.
(8) Lightning rods should be installed around the cabinet and main transformer, ensuring the equipment is within their safe protection range. Prior to the prefabricated foundation, the grounding grid should be buried first, with its grounding resistance less than 4Ω. After the cabinet is positioned, the grounding terminals should be securely connected.
(9) As the European style transformer has reached the technical requirements for unattended operation, there's no need for back-end equipment. During operation, consider reinforcing anti-theft measures.
Application Range
European-style transformers are suitable for residential communities, urban public transformers, busy city centers, construction power supply, etc. Users can choose European-style transformers based on different usage conditions and load levels.
Equipment Structure
The low-voltage room, transformer room, and high-voltage room are arranged in a Chinese character layout. An European type transformer substation integrates the transformer and standard high-voltage electrical equipment within a single metal housing. It uses common high-voltage load switches, fuses, and low-voltage switchgears, making the European type transformer substation larger in size.
Cabinet Transformer Comparison
European-style transformers have a larger volume but lower cost, while American-style transformers are compact, taking up only 1/3 to 1/5 of the volume of equivalent capacity European-style transformers. They are aesthetically pleasing, and although slightly more expensive, offer reliable power supply, reasonable structure, quick installation, flexibility, and ease of operation. They are suitable for both outdoor and indoor use.
Features of American-style transformers
American-style transformers differ from European-style transformers in that the American-style transformer integrates the transformer core, high-voltage load switch, protective fuses, and other equipment into a unified design, placed in the same oil-filled tank. It features the following characteristics:
(1) American-style transformers have a smaller volume and compact structure, about 1/3 of the same capacity European-style transformers in China; (2) American-style transformers feature a full-sealed, fully-insulated structure, eliminating the need for insulation distance, providing reliable protection for personal safety.
(3) The American-style transformer is suitable for both ring networks and terminal applications, offering great convenience in conversion and enhancing the reliability of power supply.
(4) High overload capacity
(5) Low loss, S9 or SH type available.
(6) Our company's products are used for high-voltage cable heads, capable of handling 200A load current. They can be electrically inserted and removed as load switch operations in emergencies and 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 cabinet features anti-corrosion design and special coating treatment
(10) American style transformers are arranged in a zigzag pattern. They are divided into two parts: the front section is for high and low voltage operation, which includes high and low voltage terminal connections, load switch operating handles, no-load voltage regulation section switches, insert-type fuses, oil level gauges, and more; the rear section houses the oil-filled tank and finned radiators, containing the transformer windings, core, high voltage load switch, and fuses immersed in transformer oil. Surge arresters also use oil-immersed metal oxide surge arresters. The transformer eliminates the oil cushion and is designed with a sealed oil tank following the principle of constant volume of oil and air gap, with the oil tank and radiator exposed to the air, eliminating cooling difficulties. Low voltage circuit breakers use plastic-enclosed circuit breakers as main and outgoing line circuit breakers. Due to the simplified structure, the American and European style transformers have significantly reduced footprint and volume. Their small size, combined with a single-side door, requires only 1/4 of the footprint and 1/5 to 1/3 of the volume of the equivalent capacity European style transformers.
(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, similar to the 10kV distribution transformer protection methods 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 building area of the small district is larger, the number of transformers required increases significantly, leading to more load points being connected overhead. Reducing the overhead load points necessitates increasing 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, the use of a ring network is required.
(13) Different Applicable Locations for American-style Boxes
Considering the structural characteristics and advantages/disadvantages of American-style transformers, they are suitable for power supply in multi-story residential buildings and other non-critical structures with relatively low power requirements. Based on our actual usage, American-style transformers, when paired with small ring main switch stations, are perfectly suitable for the power needs of multi-story residential buildings. Even if the transformer fails, it has minimal impact on residents, 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 buildings, high-rise buildings, and other important structures.
Product Differentiation
American-style transformer box
1) Transformer winding connection type
Single or double 10KV incoming lines
Single transformer, typically in the range of 500KVA to 800KVA; 4 to 6 low-voltage outgoing cables.
2) Key Components of the Transformer Box
Transformers, 10KV ring main switches, 10KV cable connectors, low-voltage pole terminal 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 with 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.
Drawbacks: Low power supply reliability; No electric mechanism, cannot 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, providing sound 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 various capacities, it is inconvenient to increase transformer capacity; When the transformer is overloaded or the user's capacity is increased, the civil structure needs to be rebuilt, resulting in a longer power outage period and increasing the difficulty of the project.
2. European-style Transformer Box
1) Terminal arrangement of the transformer box
a. Single unit configuration — dual 10KV incoming lines
The transformer capacity is typically 500KVA to 800KVA per unit; the low-voltage outgoing cable is usually 4 to 6 circuits.
b. Two transformer units — two 10KV incoming lines; two transformers, each with a capacity of 500KVA to 800KVA; the low-voltage outgoing cable usually consists of 8 to 12 circuits.
2) Key Components of the Transformer Box
Transformers, 10KV ring main switches, low-voltage capacitors, and low-voltage switches are the main components, effectively compactly installing the equipment of Type III stations within a metallic enclosure, thereby miniaturizing Type III stations. The volume of European-style transformers is higher and larger than that of American-style transformers, and their cost is also higher.
3) Advantages: Noise level comparable to Type III and Type I stations; lower radiation than American-style transformers due to the transformers in the European-style transformers being housed in a metallic enclosure for shielding; can be configured for power distribution automation, offering not only the benefits of Type III and Type I stations but also the main advantages of American-style transformers.
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 safety and reliability 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 extensively used in our vast cities, rural areas, industrial and mining enterprises, and public buildings.
