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The location of the electric pole was broken by a 7-seater car – Photo: NGOC HIEN
On March 22, at the scene of the driver of a 7-seater car, the 9 electric pillars broke on Nguyen U Di Street, Thao Dien District, Thu Duc City (Ho Chi Minh City), the electric poles were replanted and new transformer installation, energized as of March 20.
However, telecommunications lines are still scattered on the road, telecommunications workers are still solving the problem.
Responding to the cause of the broken power poles in the middle of the road, Mr. Le Van Khai, director of Thu Thiem Power Company, said that the impact force of the car is too strong, “which adds to the factors of impact. Target movement “.
According to Mr. Khai, a total of 9 pillars collapsed after this accident, including 4 medium voltage poles and 5 low voltage poles. Of these 9 pillars, the electric pillars that were broken by the concrete cars are the only ones that use prestressed concrete technology, the remaining pillars are old oversized steel electric poles, with an electric pole from the French period.
The objective factors explained by Mr. Khai are that there are many communication cables in the power poles, which makes the pillars heavier and more prone to breaking.
In addition, this area is small, so the electrical industry has to use a 2m steel beam (deflection beam) to take out the cable, secure the grid corridor, reduce the pole tension instead of using the 2.4 m beam to balance the two lateral.
Mr. Khai said that the above two factors that resonate with the strong force of the vehicle are the main cause of the continuous breaking of power poles.
An electric pole at the corner of the road breaks continuously – Photo: NGOC HIEN
In addition to the cause of the broken power pole, Mr. Le Van Doan, deputy director of technical charging at Thu Thiem Power Company, said that the position of the pole in the corner, a strong pole falling will pull the cables on the other poles. and then there is also a low voltage station that brings down low voltage pillars.
“The car hits the post-tensioned pillar, in terms of structure, this pillar is stronger than the other pillars, but beyond the resistance, the post will break the iron and fall” – explained Mr. Doan.
Answering the question about the quality standards of this post-tensioning post, Mr. Khai stated: Post-tensioning posts when planted on the road meet Vietnamese standards, contractors manufacture them according to that standard and ensure the requirements. of design.
Mr. Khai said that there have been many recorded cases of cars and trucks falling on individual power poles, but the number of consecutive broken columns is very rare.
Electric poles have been recently built, but telecommunication cables are still lying on the road – Photo: NGOC HIEN
According to Mr. Khai, the solution to limit similar accidents is to bury the power grid to limit the number of power poles.
At present, Thu Thiem Power Company has high underground rate, 65% medium voltage network, almost 50% low voltage, and Thao Dien area also has many underground roads. But with small roads, the alleys are not underground due to communication cables and street lighting.
In the future, the electricity sector will promote undergroundness, restricting power poles located at crossings and crossings.
Exchange with Online youthAccording to the director of an electrical network construction company, to optimize costs, Electricity of Vietnam (EVN) has used various types of prestressed centrifugal concrete electrical poles, reinforced inside the column that is to be stretched to maximum performance and still guarantee design standards.
However, this column has a disadvantage when the impact force is beyond the limit, the design will break in two, it will not tilt like conventional steel columns. According to this position, due to the impact of the chain, the surrounding columns also fell from the pull of the power transmission line.
In the 2020 rainy season, hundreds of power poles in Thua Thien Hue collapsed, including post-tensioned centrifugal reinforced concrete poles. After that, the Ministry of Construction issued a written request to Vietnam Electricity to review the quality of the power poles.
According to the Ministry of Construction, the objective reason for the number of broken power poles is due to the large number of power poles of very diverse origins, built by many actors in many stages and due to unreasonable impacts. Benefits like downed trees, landslides.
In addition, subjective reasons due to the deficiencies of the design, production, construction and installation, maintenance, have not complied with the regulations and regulations.Hobby of calculation, testing the load capacity of reinforced concrete posts in accordance with current standards for the design of reinforced concrete structures.
Previously, Thua Thien Hue Power Company stopped the use of post-tensioned centrifugal power poles after the province had hundreds of power poles broken by a Category 8 storm, although many poles were designed to withstand storms.
