Practice has proved that external lightning protection systems may cause failures after a period of use in the event of lightning currents, the effects of harsh environments, and human intentional or unintentional damage. Most of the failures are related to lightning arresters, down conductors, and grounding bodies, especially The downhole and the grounding body are corroded and broken. Next, Xiaobian took everyone to understand the problems that often encountered during the construction of lightning protection grounding construction projects and what requirements were in the construction process.
Lightning protection grounding is divided into two concepts. One is lightning protection to prevent damage caused by lightning strikes. The second is electrostatic grounding to prevent electrostatic hazards. First, the factory lightning protection is divided into the overall structure of lightning protection, which is the lightning protection of the main building, the main ground hit the grounding, grounding, forming a grounding network, grounding resistance is less than 10 euro. Then it is connected with the main steel bar or steel body. The concrete-cement roof is connected with lightning protection strips or lightning rods. There must be a grounding test point on the ground outside the wall, and the galvanized flat iron should be used as a direct guide to the roof.
Second, the grounding of the power supply system is divided into the protection grounding and the work point grounding. The protection grounding is the grounding of the live equipment housing. The grounding of the work point refers to the neutral grounding. The grounding wire practice is the same as the lightning protection grounding method, and the grounding resistance is less than 4 ohms. If the requirements are not met, a grounding electrode should be added. If the conditions are not good, the electrolyte should be added and/or the soil replaced. Working ground and protective ground are led out independently in the power distribution room. The system can be one. Working methods, such as separation of ground and neutral wires, can also be combined into a power system (or equipment). The grounding system must be grounded repeatedly.
Lightning earthing construction common problems:
First, the length of the lightning protection zone, the lead-off line, the grounding body, and the pressure equalizing ring overlap are not enough. The welding site has slag inclusion, welding pits, and pores.
Second, the ground connection of the steel mesh welding, missed welding, leaking outside the grounding connection point or detection point embedded parts.
3. When structural steels are used instead of lightning rods (nets) and their lead wires, the galvanized layer anti-rust paint is destroyed, bolts are not treated, and there are gaps between the sheets.
4. The distance between the lead-in point is too large, and the compensator is not installed at the lead-off line crossing the deformation joint. The buried depth of the grounding body installation is not enough or the lead-out line is not treated for anti-corrosion.
5. Roofing metal objects (such as pipes, ladders, flagpoles, and equipment enclosures) are not connected to the roof lightning protection system, and the equipotential bonding across the ground wire is insufficient.
6. The grounding (zeroing) branch of the electrical equipment is not connected to the grounding trunk.
Lightning protection grounding requirements:
1. The material meets the specifications and design requirements, the connection is reliable, the anti-corrosion measures are in place, and the grounding system is unimpeded and complete.
2. Using the building foundation steel as the grounding body and the down-lead connection specification, the data is complete; the lightning protection zone, the grounding line are installed straight, beautiful, fixed firmly; the roof and the exposed metal components are grounded intact; the equipment metal enclosure and the device grounding are not Missing.
3. The grounding point is clearly marked and the grounding test points are complete.
4, grounding line lap meets the requirements.
The above is a brief introduction for Xiaobian. If you want to know more related information, please continue to pay attention to Qijia Consulting. More exciting consultation, please stay tuned.
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