YBD-12 Underground Prefabricated Substation

Product Overview

As urban land becomes increasingly scarce and residents demand more of their living environment, traditional box-type substations are increasingly criticized for their bulky volume and monotonous appearance, which often causes conflicts between users and power supply departments over the site selection of distribution equipment. In response to this market demand, and on the basis of years of experience in producing underground transformers, our company has developed a new type of box-type substation — the light-box underground substation — with a small footprint, elegant appearance and high harmony with the surroundings.

The YBD-12 underground prefabricated substation mainly consists of two parts: an underground transformer (with prefabricated pit) installed below ground, and an outdoor advertising light-box HV/LV switchgear installed above ground. The underground transformer is a new type of distribution transformer with HV fuse protection that can operate submerged in water for a period of time, and has been widely used in airports, expressways, bridges and tunnels in China. The inside of the outdoor light-box HV/LV switchgear is an outdoor HV/LV distribution cabinet, and the outside of the tank is an advertising light box; the advertising content can be designed according to the surroundings and user requirements. The whole product occupies little land and is elegant; it is not only highly harmonious with the surroundings but also serves advertising purposes.

Type Designation

Service Conditions

• Altitude: not exceeding 1000 m;
• Ambient temperature: maximum +50℃;
• Minimum temperature: -25℃;
• Relative humidity: daily average not exceeding 95%;
  monthly average not exceeding 90%;
• Installation inclination not exceeding 3 degrees, no places with frequent violent vibration and shock;
• The surrounding air is free of explosive gases and not obviously polluted by corrosive or combustible gases.

Product Advantages

Compared with traditional box-type substations, this product has the following significant advantages:

◆ High reliability

◇ The underground transformer selected for the YBD-12 underground prefabricated substation has an anti-corrosion stainless-steel, fully sealed tank; the HV and LV incoming/outgoing lines adopt waterproof, fully sealed, fully insulated and fully shielded connections, ensuring the anti-corrosion and sealing capability of the buried transformer, with overall protection class reaching IP68, allowing short-time submerged operation. The HV protection configuration is flexible: it can be protected by an SF6 fully-insulated ring main unit, or full-range protection can be provided at the front end of the underground transformer by an oil-immersed load switch plus bayonet fuse and backup fuse. When a transformer fault occurs, the fault point can be cut off quickly without affecting the operation of the whole line.

◇ The pit foundation is designed and made with waterproofing and drainage in mind: the top vent has effective rain and water protection, the sides and bottom are treated with special waterproof materials, and the cable entry holes all use Roxtec sealing systems to ensure no water seepage. The pit is fitted with an internal-external automatic heat exchange system, and an automatic drainage control system is installed at the bottom. The buried substation can operate submerged in water and withstand floods; all these measures guarantee a 20-year service life of the buried transformer, maintenance-free and inspection-free, effectively improving the reliability of the power supply system.

Energy Saving

The underground transformer selected for the YBD-12 underground prefabricated substation is a low-loss S11 wound-core transformer; its no-load and load losses are significantly lower than those of traditional laminated-core transformers (compared with S9, no-load loss reduced by 30% and load loss by 15%).

Noise Reduction

As is well known, the main factor of the influence of box-type substations on surrounding residents is transformer noise. The noise mainly comes from the core; a transformer installed in an ordinary box-type substation is usually about 1.2 m above ground, and if the substation is close to residential windows, the noise will inevitably enter residents' rooms at night and affect sleep. Once the transformer or the whole substation is installed underground, the noise drops significantly and has almost no effect on residents.

High Automation

The YBD-12 underground prefabricated substation can report the operating status of the underground combined transformer and the HV/LV switchgear to management personnel via a comprehensive measurement & control device using GPRS wireless network technology (our patented product), greatly facilitating the control and use of the substation.

Aesthetics & Environmental Harmony

Traditional box-type substations are too bulky to harmonize with the surroundings. Especially in high-end residential quarters and commercial streets where land is extremely precious, it is difficult to find a site for a bulky substation, which lowers the overall taste of the community and may even affect the sales of nearby buildings. Since the transformer of the light-box underground substation is installed underground, it does not affect the surroundings; the above-ground distribution cabinet is small and easily harmonizes with the environment. For example, in residential quarters the above-ground cabinet can match the community greening and become part of the landscape; on urban arterial roads and expressways, the above-ground cabinet can be designed as an advertising light box.

Creating Value for Customers

• The light-box underground substation occupies little land, can replace traditional distribution rooms, reduces the construction of distribution rooms, lowers investment cost and shortens the construction period. It is elegant and harmonious with the surroundings; installed in residential quarters, it not only does not affect the prices of nearby buildings but also improves the living taste of the community.
• The light-box underground substation installed on urban arterial roads and expressways has advertising light-box switchgear above ground, which not only beautifies the environment but also brings long-term advertising revenue to customers.

Advertising Light-box HV/LV Switchgear

The switchgear adopts a double-door structure with protection class IP34. The first layer is the advertising light box, whose shell is fitted with hydraulic rods and can be opened 90 degrees; the second layer is the switch door, ensuring that after the light-box shell is damaged, the HV/LV equipment still has independent enclosure protection.

The locks of the first and second layers are independent; light-box maintenance does not affect the operation of the switchgear.

It can be customized as advertising light boxes on both sides, or one side advertising light box and the other side an HD LED screen; the light source uses LED elements with small volume and uniform light.

The light-box shell is fitted with an alarm device; if damaged by external forces, an alarm signal is issued immediately.

Underground Transformer

The S11-M·R·D series underground transformer is installed in a pit without direct public contact and can operate submerged in water for a certain period of time.

The transformer has HV fuse protection inside.

Prefabricated Pit

The prefabricated pit is of fully sealed waterproof design, stamped from integrally hot-dip galvanized steel plates; precast reinforced concrete structure is also available. Waterproof treatment ensures no leakage.

The pit cover uses precast cement slabs to prevent surface water and other debris from entering the pit.

Decorative floor tiles are laid on the pit cover, with a lockable manhole cover plate.

Main Technical Parameters

Complies with the standard GB/T17467-1998 "High-voltage/low-voltage prefabricated substations"

Note: The underground transformer complies with the machinery industry standard JB/T 10544-2006 for underground transformers.

Notes:

• This product consists of an underground transformer, a light-box outdoor HV/LV switch cabinet and a prefabricated pit.

• The light-box outdoor HV/LV switch cabinet is of double-door design; even if the light box is damaged, the HV/LV equipment still has independent enclosure protection.

• The prefabricated pit is of fully sealed waterproof design; decorative tiles are laid on the pit cover with a lockable manhole cover plate.

• Both the HV and LV sides of the underground transformer adopt simultaneous three-phase cable plug-in/out connections, with sealing up to IP68, allowing long-time submerged operation.

Related Products

Box-type substations of the same series and other types available:

• YBW-12 Prefabricated Box-type Substation (European)
• YB-40.5 Wind Power Box-type Substation
• ZGS-12 Combined Substation (American)