Lightning protection construction site is an important work can not be ignored. This concerns the safety of the building facilities, construction equipment and personnel. In particular, according to the statistical data of the National Weather Service, the frequency of lightning disasters has risen year by year due to the urban heat island effect in many areas in our country in recent years, and the lightning protection of the construction sites undergoing overall changes should be given more attention.
First, the lightning rod settings
The installation of lightning rod is the main measure to prevent direct lightning.
When the construction site is located in the mountains or more thunder area, substations, distribution should be equipped with an independent lightning rod. The construction of the building under construction, when the height of more than 20m should be equipped with lightning rod. Tower cranes, well-shaped frames and scaffolding machinery inside the construction site shall be installed with lightning protection devices if they are outside the protection range of the lightning protection settings of the adjacent buildings and structures and within the range specified in Table 1. If the highest mechanical equipment on the lightning rod, and should ensure that the final exit from the scene, the other equipment may not set up lightning rod.
Xian construction machinery and equipment need to install the provisions of the lightning rod
Lightning rod lightning rod generally used Ñ„16mm round bar, a length of 1 ~ 2m, the top of the car should be made cone tip. The lightning receptor must be hot-dip galvanized.
Lightning protection equipment lightning rod can take advantage of the metal structure of the device, but should ensure that the electrical connection. Machinery and equipment of all power, control, lighting, signal and communications lines, should be laid steel pipe. Steel pipe and mechanical structure of the metal structure for welding to ensure that the grounding channel of the electrical connection.
Second, lightning arrester
Arrester is installed to prevent lightning invasion of the main measures.
High voltage overhead lines and high voltage side of the power transformer should be installed arrester, arrester installation location should be as close to the substation. Lightning arresters should be installed between high-voltage fuses and transformers to protect the power transformer circuits from lightning strikes. Arrester can be used FS-10-type valve arrester, arrester rod arrangement should be neat, consistent high and low. 10kV surge arresters installed phase spacing of not less than 350 mm. Arrester lead should strive to achieve short straight, relaxation moderate, close connection, the lead on the general use of 16mm2 copper core insulated wire, lead wire generally used 25mm2 steel core insulated wire.
Lightning arrester grounding lightning using "three in one" of the wiring, namely: arrester grounding lead, power transformer metal shell grounding lead and transformer low-voltage side of the neutral point of the three connected together, and then common Connect with the grounding device. In this way, when the high-voltage side of the lightning arrester lightning discharge, the transformer insulation withstand voltage, arrester residual voltage, will not damage the transformer insulation.
At the low voltage outlet of Dorei District, a set of LV arresters should be installed to prevent the low voltage side dielectric breakdown due to the lightning on the low voltage side or the voltage wave of positive and negative conversion. Low-voltage arrester can be used FS series of low-voltage valve arrester or FYS low-voltage metal oxide surge arresters.
It should also be noted that arresters should be tested for prophylaxis before and during the annual March. After testing confirmed that the qualified state can be put into use.
In addition, the substation of the low-voltage overhead line or outlet, it is appropriate to connect the insulators iron feet with the distribution of the grounding device with Ñ„8 bar. The purpose of this is also to prevent lightning intruding waves.
Third, to prevent lightning induced measures
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