We will present the performance, safe operation methods, and technical parameters of YBBD-12 Pad Mounted Transformer
1. Frontier
YBBD-12 series semi-buried box substation (referred to as semi-underground box substation, also known as landscape underground box substation) is a new generation of box transformer newly developed on the basis of full research and discussion of modern urban construction and management. Its main part is buried underground, occupying little or even no land, the visual effect is very good, effectively solving the contradiction between urban land shortage and urban psoriasis, harmonious and unifying with the surrounding environment, and is highly regarded by the majority of experts and users. Semi-buried box substation refers to the complete set of the box substation is all installed in a fully sealed box and the whole is set below the ground level, it is the same as the ground box type substation, the internal equipment is the same, the same 10KV input voltage is reduced to 400/220V distribution voltage by the transformer and then sent to the load point, which can be used for ring network distribution system, and can also be used as a radial power grid terminal power supply substation. The semi-buried box has excellent anti-corrosion and pressure resistance, and has absolute sealing.
The pursuit of "novelty" and "beauty" and the environmental protection of modern urban power facilities are the trend of today's power construction and development, and it is also an important symbol of the degree of modernization and civilization of a city. With the purpose of creating first-class power equipment, beautifying the urban environment and serving the society, our company actively strives to solve the current power equipment installation and maintenance, such as overhead line underground engineering, coastal typhoon salt spray erosion, environmental vision and many other difficulties, and introduces and absorbs foreign advanced technology to develop environmentally friendly non-metallic semi-buried box substations.
2. Overview
2.1. Model and meaning:
Y B BD □ / 0.4 □
└─ Rated capacity of transformer KVA
└─Rated voltage KV on the low voltage side
└─ Rated voltage on the high voltage side KV, 12, 40.5
└─Installation method, BD semi-buried installation
└─Box substation
└─Pre-installed
2.2. Conditions of use:
Normal conditions of use
a) Altitude
The altitude does not exceed 1000m
b) Ambient temperature
Maximum temperature +40°C
Minimum temperature -30°C
c) Relative humidity
At 25°C, the relative humidity of the air does not exceed 95%, and the monthly average does not exceed 90%.
d) Installation environment
The installation environment should be free of obvious dirt movement, explosive, corrosive gases and dust. The installation site should be free of violent vibration and shock and cannot be placed in low-lying places.
Special conditions of use
In addition to the above normal conditions of use, other conditions of use are in accordance with the provisions of GB1094.1, GB/T11022, GB/T14048.1 and GB7251.1.
2.3. Main parameters:
serial number | Items | unit | High voltage unit | transformer | Low pressure chamber | |
Load switch | Fuse | |||||
1 | Rated voltage | kV | 12 | 10/0.4 | 0.4 | |
2 | Rated current | A | 630 | 12-125 | 300-2500 | |
3 | Rated power frequency withstand voltage | kV | 42/48 | 35 | 2.5 | |
4 | Rated lightning impact resistance | kV | 75/85 | 75 | 8 | |
5 | Rated breaking current | kA | 20 | 31.5 | ||
6 | Rated short-circuit closing current | kA | 50 | |||
7 | Rated peak withstand current | kA | 50 | |||
8 | Rated for short-term withstand current | kA | 20 | |||
9 | Rated capacity | kVA | ≤1600 | |||
10 | Noise level | dB | <55 | |||
11 | Protection level | High Voltage Chamber IP33, Transformer Chamber IP23, Low Voltage Chamber IP33 | ||||
Structural features:
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| Fig. 1 Schematic diagram of semi-buried box transformer structure 1-Light box-type power distribution equipment: 2-High-voltage cable inlet hole; 3-Underground combined transformer: 4-Pitpit foundation installation hole 5-Prefabricated ground play foundation; 6-Low-voltage cable outlet hole; 7-Pit operation port cover |
3.1 Structure
The structure of the semi-buried box transformer is shown in Fig. 1.
Semi-buried box transformers are mainly composed of underground transformers and advertising light box outdoor switchgear. The underground transformer is a new type of compact substation equipment that combines transformers, high-voltage load switches, fuses, etc., which is installed in the pit, does not occupy surface space, and can be submerged in water for a period of time. The advertising light box type outdoor switchgear is a mixed structure integrating billboards and outdoor switchgear, which is installed on the ground. The inside of the box is an outdoor high and low voltage distribution cabinet, and the two sides are advertising light boxes, which has excellent visual effects.
3.2 Structural characteristics
3.2.1 Underground combined transformer
The underground combined transformer used in underground transformer has the following characteristics:
(1) The box is made of stainless steel, fully sealed, with a protection level of IP68, and can be immersed in water for operation.
(2) The high and low voltage inlet and outlet lines adopt waterproof and fully sealed, fully insulated, and fully shielded wiring methods, which are safer to operate.
(3) Naphthenic alkyl transformer oil is used to ensure good heat dissipation capacity,
(4) Amorphous alloy iron core can be used, which has a significant energy-saving effect.
(5) High insulation heat resistance level and environmental protection.
(6) Backup and plug-in fuses give the transformer safer protection.
(7) The load switch has two, three and four positions, which is suitable for a variety of power supply systems.
3.2.2 Prefabricated pit foundation
The pit foundation of the buried transformation is prefabricated in the factory, and the prefabricated pit foundation has the following characteristics:
(1) The foundation of the pit can be pre-pressed with steel plates above 6mm, and the structure is fully sealed to ensure that surface water and other debris cannot enter the pit: prefabricated reinforced concrete structure can also be used, and advanced waterproof technology is used to ensure that the foundation does not leak.
(2) A water collection tank is provided at the bottom of the pit, and a submersible pump controlled by the automatic drainage system is installed.
(3) High and low voltage cable mounting brackets are installed in the pit to facilitate cable installation and fixation.
(4) Waterproof lighting is installed in the pit for easy maintenance.
(5) The foundation top cover is equipped with an open manhole.
3.2.3 Outdoor switchgear of advertising light box
(1) The protective shell of the switchgear adopts the structure of the advertising light box, and the two doors of the light box shell can be opened at all angles, and there is a pneumatic spring support positioning, which is convenient for the operation and maintenance of the switchgear.
(2) The light box is equipped with a thermal insulation layer, which has a good thermal insulation effect.
(3) The two sides of the light box shell are advertising boards, and LED light-emitting elements with small size and uniform light source are adopted.
(4) The door lock of the advertising light box and the switchgear is set independently, and the maintenance of the light box does not affect the operation of the switchgear.
(5) The light box shell is equipped with an audio and light alarm device, which can send an alarm signal if it is damaged by the outside world.
(6) The switchgear adopts a double-layer door structure, the protection level reaches IP34, and the second layer is the instrument door to ensure that after the light box shell is destroyed, the low-voltage cabinet still reaches the protection level of a complete and independent outdoor low-voltage product.
(7) The fan hidden in the light box shell can automatically exhaust and supply air to the pit foundation to reduce the temperature and dehumidify.
3.3
Waterproof and heat dissipation
3.3.1 Waterproof treatment of underground transformation
Although the underground combined transformer of the underground box transformer is allowed to operate under water, the waterproofing and drainage in the pit foundation is carefully designed for the long-term safe and reliable operation of the underground transformer.
For areas with low groundwater level (lower than the bottom of the pit foundation), a prefabricated pit structure is adopted, the ventilation hole at the top of the pit has effective ventilation and rainproof ability, and the bottom of the pit foundation is laid with water-running sand pebbles, and the water can directly seep into the ground.
3.3.2
Heat dissipation of buried changes
The underground box transformer mainly ensures the temperature rise and heat dissipation of the underground transformer from the following aspects:
(1) Underground transformers use 11 series low-loss products or amorphous alloy core products, which greatly reduce no-load loss and load loss, so the heat generation is low.
(2) The heat resistance level of the transformer is high, with a large temperature rise margin, which also improves the overload capacity of the transformer.
(3) The underground transformer uses naphthenic transformer oil (or high ignition point oil), which can flow continuously at extremely low temperature without adding additives, and its good viscosity-time characteristics make the flow speed of the oil speed faster when the temperature rises, ensuring that the product has good heat dissipation ability.
(4) Between the distribution box and the foundation pit, inlet and outlet fans are set up, and the forced transmission/exhaust air cooling is carried out when the temperature rise of the underground combined transformer reaches the set value to ensure the normal progress of the underground transformer.
