S13(22)-MD Underground Transformer
1.1 Types and meanings of underground distribution transformers
Buried Transformer
Product Overview
A buried transformer is a distribution transformer or combined transformer designed for installation in an underground pit. It can form a compact power distribution system by integrating the transformer, high-voltage load switch and protective fuse inside the tank.
The product is designed according to JB/T 10544-2006.
Buried transformers are suitable for long-distance, low-load high-voltage transmission systems used along roads, bridges and tunnels. They can also be used in projects where overhead power lines are converted into underground systems, as well as in residential community power supply networks.
The product is widely used in three-phase, 50 Hz underground transmission and distribution networks with voltage levels of 10 kV and below. Typical applications include urban main roads, airports, bridges, tunnels, large green areas, parks and other locations requiring reliable power distribution and lighting with minimal impact on the surrounding environment.
Pre-Assembled Buried Transformer Box-Type Substation
The pre-assembled buried transformer box-type substation consists of a buried transformer, advertising light-box-type switchgear and a prefabricated pit. The complete system is assembled and tested at the factory before delivery.
The equipment is divided into underground and above-ground sections. The underground section includes a prefabricated pit, or a pit cast on site, together with the buried transformer.
The above-ground section includes advertising light-box-type outdoor switchgear, or conventional outdoor switchgear, as well as ventilation and heat dissipation channels.
The product is suitable for different urban power distribution systems, especially underground cable conversion projects and other municipal power supply construction projects.
Landscape Buried Box Transformer
The landscape buried box transformer is independently developed and manufactured by the company. It consists of a buried combined transformer, outdoor high- and low-voltage cabinets, a light-box-type protective enclosure and a prefabricated buried transformer foundation.
Its appearance can be customized according to the surrounding environment, allowing the equipment to better match and improve the local landscape.
Product Features
- The product requires little installation space, occupies no surface area, provides a good landscape effect and is simple to construct.
- It can be installed close to the load center and supports decentralized power supply. This reduces the number of low-voltage cables, lowers investment costs and decreases line losses.
- The enclosure has an IP68 protection rating and explosion-resistant performance. It can remain fully submerged for a certain period, improving the reliability of the power supply system.
- The oil tank adopts a fully insulated, fully sealed and fully welded structure. It can withstand a pressure of 70 kPa without oil leakage or deformation.
- The fully insulated structure eliminates the need for insulation clearance and improves personal safety.
- A specially designed radiator provides sufficient mechanical strength and effective heat dissipation.
High- and Low-Voltage Cable Connection Methods
- Three-phase cable connectors can be inserted into the transformer at the same time and used together with special cable plug connectors. This method is suitable for three-phase buried transformers with voltage levels of 10 kV and below and capacities of 400 kVA and below.
- Single-phase cable connectors can be used together with elbow-type detachable cable plugs. This method is suitable for three-phase buried transformers with voltage levels of 10 kV and below and capacities of 1,600 kVA and below.
- The connector is filled with a patented insulating liquid whose specific gravity is greater than that of water. The connector insulating liquid is separated from the transformer oil, helping maintain normal operation even when water enters through capillary action.
Additional Functions
The transformer can be equipped with an oil-immersed load switch. This allows switching operations under load and supports both ring-network and terminal power supply modes.
The operating mode can be changed conveniently, helping improve power supply reliability.
The light-box-type switchgear used with the pre-assembled buried transformer box substation is easy to install and provides a modern appearance. The advertising light box can also be used for commercial advertising.
The pre-assembled buried transformer box substation uses natural ventilation. The transformer, underground pit and light box are designed together for overall temperature-rise control.
When the transformer operates at rated load inside the pit, its temperature rise meets the requirements of GB 1094.2.
The underground pit can also be equipped with an automatic drainage system. The system starts automatically when flooding or other special conditions occur.
