Underground combined(transformer substation)

　　What is buried box transformer?

　　Buried box-type substation is also known as buried substation, landscape box-type substation, underground substation, sunken box-type substation, etc., which is mainly called by its structure and external appearance. Buried box transformer is composed of buried transformer, fully insulated and fully enclosed high-voltage cabinet, low-voltage cabinet, light box type low-voltage maintenance enclosure, etc. The manufacturing and commissioning of all equipment shall be completed in the complete plant in advance, and the power transmission shall be assembled at the construction site.

　　PRODUCT DESCRIPTION

　　ZBW-D serial underground combined transformer substation is a full set of power distribution & transformer devices which integrate high voltage switch cabinet, buried transformer, low voltage power distribution cabinet etc. into one. In order to meet the requirements of urban construction and environmental protection, our company develops and designs a series of products based on the combined substation. Underground combined transformer substation has the advantages such as advanced technology, attractive model, low noise, safe and reliable running, convenient maintenance, compact structure, small covering area etc. It is applicable for power distribution and transformer occasions such as public city areas, street, park, residential quarters and scenic districts and so on. It is used as receiving and distributing electric energy in power distribution system. It can be used in ring net power distribution system, dual-power or emission terminal power distribution system.

　　1. Structural characteristics of buried box transformer

　　1.1 Structure

　　The buried box-type transformer is mainly composed of buried transformer and box-type outdoor switchgear. Buried transformer is a new type of compact substation equipment, which is composed of transformer, high-voltage load switch, fuse, etc. It is installed in the pit, does not occupy the surface space, and can operate under water for a period of time. The box-type outdoor switchgear is a hybrid structure integrated with outdoor switchgear and installed on the ground. The interior of the box is an outdoor high and low voltage distribution cabinet, which has a small floor area and does not affect the ground building facilities.

　　1.2 Structural characteristics

　　1.2.1 Underground combined transformer

　　The underground combined transformer adopted by the underground box transformer has the following characteristics:

　　(1) The box is made of stainless steel, fully sealed, with protection grade of IP68, and can be immersed in water for operation.

　　(2) High and low voltage incoming and outgoing lines adopt waterproof, fully sealed, fully insulated and fully shielded wiring mode, which makes the operation safer.

　　(3) Naphthenic base transformer oil is used to ensure good heat dissipation

　　(4) Amorphous alloy iron core can be used, with remarkable energy-saving effect.

　　(5) High insulation and heat resistance, environmental protection.

　　(6) The backup and plug-in fuse can provide safer protection for the transformer.

　　(7) The load switch has two, three and four positions and is applicable to various power supply systems.

　　1.2.2 Prefabricated pit foundation

　　The pit foundation of the buried box transformer is prefabricated in the factory. The prefabricated pit foundation has the following characteristics:

　　(1) The foundation of the pit can be pre-pressed with steel plates of more than 6 mm and fully sealed to ensure that surface water and other sundries cannot enter the pit; the prefabricated reinforced concrete structure can also be used, and advanced waterproof technology can be used to ensure that the foundation does not leak

　　(2) The sump is set at the bottom of the pit, and the submersible pump controlled by the automatic drainage system can be installed.

　　(3) High and low voltage cable mounting brackets are installed in the pit to facilitate cable installation and fixation.

　　(4) A waterproof lamp is installed in the pit for easy maintenance.

　　(5) The foundation top cover is provided with an openable manhole.

　　1.2.3 Box-type outdoor switch gear

　　(1) The protective enclosure of the switch gear adopts a box-type structure. The two doors of the enclosure can be opened from all angles and are supported and positioned by pneumatic springs, which is convenient for the operation and maintenance of the switch gear.

　　(2) The box transformer is equipped with thermal insulation layer, which has good thermal insulation effect.

　　(3) The switch gear adopts double-layer door structure, and the protection level reaches the national standard.

　　(7) The fan hidden in the box transformer can automatically exhaust and supply air to the pit foundation to reduce the temperature.

　　1.3 Waterproof and heat dissipation

　　1.3.1 Waterproof treatment of buried transformer

　　Although the underground combined transformer of the buried box transformer is allowed to operate under water, in order to ensure the long-term safe and reliable operation of the underground transformer, the waterproof and drainage in the pit foundation must be fully considered and designed.

　　For areas with low groundwater level (lower than the bottom of the pit foundation), the prefabricated pit structure is adopted. The ventilation hole at the top of the pit has effective ventilation and rain-proof capacity. The bottom of the pit foundation is paved with water flowing sand pebbles, and the water can directly seep into the ground. For areas with high groundwater level (higher than the bottom of the pit foundation), the prefabricated fully enclosed concrete pit structure is adopted to prevent surface water from entering and groundwater from seeping into the pit.

　　1.3.2 Heat dissipation of buried transformer

　　The underground box transformer mainly ensures the temperature rise and heat dissipation of the underground transformer from the following aspects:

　　(1) The underground transformer adopts S11 series low-loss products or amorphous alloy iron core products, and the no-load loss and load loss are greatly reduced, so the heat generation is low.

　　(2) The transformer has a high heat resistance grade and a large temperature rise margin, which also improves the overload capacity of the transformer.

　　(3) Air inlet and outlet fans are set between the distribution box and the foundation pit. When the temperature rise of the underground combined transformer reaches the set value, forced air supply/exhaust cooling is conducted to ensure the normal operation of the underground transformer.

　　PRODUCT DESCRIPTION

　　2.1 Altitude: ≦ 1000m

　　2.2 Environmental temperature: Highest 40℃ and lowest -25℃ No more than 30℃ for highest average daily temperature Daily range of temperature ≤ 20℃

　　2.3 Relative air humidity : ≦ 90%(+25℃ )

　　2.4 Outdoor wind speed : ≦ 35m/s

　　2.5 Ground inclination: ≦ 3°

　　2.6 The installation site shall be free from explosion, debt, serious pollution, chemical corrosion and severe vibration.

　　2.7 If above use conditions can not satisfy your demands, the user can discuss with the company for a better solution