Regarding the box-type substation, it will also be called a prefabricated substation, or a prefabricated substation. It is an important substation and distribution facility that we need to use in our lives, factories and enterprises. Since it is so important, of course, it needs to be carefully designed in the installation process, so what are the installation precautions for box-type substations? What are the installation requirements? Let's talk about this today.
The problems that should be paid attention to in the construction and operation of box-type substations are mainly divided into two points:
First, it is necessary to correctly select the low-voltage common ground bus. According to Article 5.1 of "Guidelines for Selection of High Voltage/Low Voltage Prefabricated Substations" DL/T537 2002: Copper conductors should be used for grounding conductors, and the minimum cross-sectional area should not be less than 30mm2. Some boxes have become cost-saving and the choice of aluminum material does not meet the requirements of the regulations. Some people think that this wire doesn't carry working current and is insignificant, which is wrong. At the same time, this line plays an important role in effectively reducing the fault contact voltage and preventing electric shock damage. After increasing the cross-sectional area of ​​this line, the selection area of ​​the conductive lines in the box transformer can be greatly reduced after calculation, so it should be more cost-effective to reduce the overall cost.
Second, the grounding grid of the box-type substation should be buried below 1m. The foundation of the box-type substation is generally less than 10m2, and the size is relatively small, while the grounding grid is relatively large, and it needs to be extended to the surrounding farther places. In order to reduce the grounding resistance, some vertical grounding electrodes must be added. In order to reduce the ground voltage distribution and not cause other damage to the surrounding, the grounding grid should be buried as deep as possible.
The installation requirements of the box-type substation are as follows:
First, the box-type substation is mainly cooled by natural air circulation. Therefore, there should be no illegal piles around it, especially the door of the transformer room should not be blocked, and the attachments on the ventilation holes of the shutters should be removed frequently to ensure that all electrical equipment does not exceed the maximum allowable temperature.
Second, the floor of the box-type substation should be placed in a higher place, not in a low-lying place, so as to avoid rainwater pouring into the box and affecting the operation of the equipment.
Third, zinc oxide arresters should be installed in the high-voltage distribution room of box-type transformers, and the installation method must be convenient for testing and disassembly and replacement.
Fourth, the box door of the box-type substation should be opened outward, and there should be handles, concealed latches and locks, and the concealed latches and locks should be rust-proof.
Fifth, the noise level of the box-type substation should not be greater than the specified noise level of the transformer. Regardless of whether the box shell is made of metal or non-metallic materials, the metal frame of the box body should be well grounded, with grounding terminals, and marked with grounding symbols.
Sixth, the transformer room should be dominated by natural ventilation, and the relationship between the temperature in the box and the output of the transformer should be given. The transformer room can be equipped with a room temperature monitoring device and a self-starting ventilation cooling device as required to ensure that the transformer runs at full load under the specified environmental conditions. The transformer should be accessible from the top of the box or from the side door.
Seventh, the grounding and neutral line of the box-type substation share a grounding grid. The grounding grid is generally grounded at the four corners of the foundation, and then connected into one. The box-type substation and the grounding grid must have two reliable connections.
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