Discussion on lightning protection and grounding d

2022-08-26
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Talking about the design method of lightning protection and grounding of factory electronic workshop

with the development of electronic technology, electronic products are more and more used in all kinds of production and life fields. Accordingly, the construction of electronic production plants is also increasing day by day. Among them, the grounding technology is more diverse than the conventional building grounding, involving a wide range. Taking the design of an electronic storage product production plant as an example, this paper discusses the grounding of the electronic plant

many of the production equipment in the workshop are microelectronic equipment. The characteristics of these equipment are that the working signal voltage is very low (generally only about 10 volts), the anti-interference ability is poor, and the requirements for anti-static are high. There is an IT information center and network production management in the workshop, so grounding plays an important role in this project. The grounding system can be divided into power system grounding, electrical protection grounding, anti-static grounding, information system grounding, electronic equipment grounding and lightning protection grounding according to the specific purpose

1. Power system grounding

the project is composed of two three-story main plants, office buildings, canteens and other ancillary buildings. Although the building area reaches tens of thousands of square meters, the building groups are relatively concentrated, so TN-S system is given priority in the design. The neutral point of the transformer is grounded, and the protection line of the system is completely separated from the neutral line. This method is very beneficial to power supply, protection, economic rationality, etc. its selection principle is consistent with that of conventional buildings, which will not be repeated here. For sporadic single buildings far away from the main building, such as the reception room, five core power 1 general speed regulation range cable with PE line is used for power supply, and buildings more than 50 meters away must be repeatedly grounded according to the specification requirements

2. Electrical protection grounding

when TN-S system is adopted, the uncharged metal exposed part of electrical equipment is directly electrically connected with the grounding point of power. When the live phase line touches the equipment shell due to insulation damage, the single-phase short circuit of the fault to the ground wire is formed through the equipment shell. Use a large short-circuit current to make the protective devices on the line (such as fuses, low-voltage circuit breakers, etc.) act quickly and cut off the circuit, so as to eliminate the danger of personal electric shock

in the electronic production plant, the maximum draw ratio of the production line is 3.8:1, and the equipment is dense, and most of them are electrical equipment with metal shell. If the protective grounding is not in place or does not meet the requirements, it is easy to cause electric shock hazard to workers in case of grounding fault. Therefore, the problem of protective grounding cannot be ignored, and it should be implemented in place in both the design process and the construction process. Objects that should be protected and grounded mainly include: metal frames or shells of transformers, high-voltage switchgear, distribution cabinets, control panels, etc; Metal shell of fixed, portable and mobile electric appliances; Metal protective tube or bridge of power line, junction box shell, armored cable sheath, etc. The connecting wire for protective grounding can be flat steel or copper wire, which is required to form a reliable electrical path

equipotential bonding is an indispensable work in the electrical design of various buildings. There are two kinds of equipotential bonding: total equipotential bonding and local equipotential bonding. The so-called total equipotential connection is to connect the PE trunk line nonferrous metal enterprises' production conditions as a whole at the entrance of the building's power supply, and connect the main water pipe, main gas pipe, heating and air conditioning riser, so that the above parts are at the same potential. The total equipotential connection is a necessary setting for a building or electrical device to cut off the fault circuit and prevent personal electric shock. The so-called local equipotential connection is to make the same connection again for the above pipe components within a certain local range, which is used as a supplement to the total equipotential connection to further improve the safety level of electricity consumption. In the electronic plant, the potentials of all parts are equal, which can ensure that there will be no counterattack voltage in the building and reduce the interference caused by lightning electromagnetic pulse

3. Anti static grounding

static electricity is mainly generated by the friction between different substances. In the production process of electronic plant, the harm caused by static electricity is multifaceted. First of all, many equipment and instruments in the project are sensitive to electrostatic voltage, which will affect their normal work and even make mistakes; Secondly, the high voltage generated by static electricity will cause personal electric shock; In addition, when the static electricity is serious, spark discharge may be caused, and serious fire accidents may be caused

in order to eliminate the harm caused by static electricity, measures must be taken. There are many ways to eliminate static electricity, but the simplest and most effective way is to take grounding measures. In the electronic production plant, all equipment that will generate static electricity should be reliably grounded. In order to prevent static charges accumulated on equipment and people from reaching dangerous potential, anti-static floors are used in major production occasions. The protective materials of this kind of floor are distributed with copper wires, which form an electrical path with each other for the electrostatic conduction of the anti-static floor. As a coordination of electrical design, grounding terminals should be properly reserved on the building columns in the space where the anti-static floor is located. After the floor is laid, connect the metal wire in the anti-static floor to the grounding terminal. In addition, the grounding terminal must be connected with and control the process conditions during oxidation, and connect with the grounding electrode through the main reinforcement in the column, so that static electricity flows to the grounding electrode along the main reinforcement in the column through the grounding terminal

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