With the continuous progress of urban construction and development, the construction of modern building projects not only requires the beautification of appearance, but also requires the quality of its safety performance. People have strict requirements for the safety of residential buildings. Lightning protection detection of residential buildings has become one of the important aspects to improve the safety factor of buildings.
Why should lightning protection devices be inspected every year? Because regular testing of lightning protection devices is one of the tasks of lightning protection and disaster reduction. It is required that personnel of lightning protection testing institutions must have relevant qualifications, hold certificates to work, carry out lightning protection testing inquiry, inspection, measurement, calculation and other work processes, and vigorously publicize knowledge of lightning protection and disaster reduction. , constantly improve the testing specifications of lightning protection devices, strengthen the maintenance and testing of lightning protection devices, improve the public’s awareness of lightning protection testing and the testing level of lightning protection testing departments. Regular testing of lightning protection devices is the main task of lightning protection testing agencies at all levels, and is also the focus of safety performance testing of the entire lightning protection device. Negligence in detection of any part may cause lightning accidents and disasters.
According to incomplete statistics, a total of 16 lightning accidents occurred in Shanghai from 2012 to 2017, damaging more than 28 pieces of equipment and causing serious property losses and casualties. The reason is that unqualified lightning protection devices and failure to conduct regular inspections in a timely manner are one of the main causes of lightning accidents.
Metal oxide arrester
1. Composition of lightning protection device
Lightning protection devices include lightning arresters, down conductors, grounding devices, surge protectors and busbar connecting conductors. Lightning arresters include lightning rods (belts, nets, wires) that directly receive lightning strikes, metal roofs, and components that receive lightning strikes; the down conductor is a metal conductor that connects the arrester and the grounding device, and is used to guide the lightning current received by the arrester into the earth through the down conductor. After the down conductor is connected to the arrester, a path is established for the lightning current to drain into the earth; the grounding device is the general term for the grounding body and the grounding wire. The grounding body is buried in the soil or a concrete foundation and is used to discharge lightning current. The grounding wire is a conductor that connects the grounding body at the disconnection point. In parallel or series connection in the line, the instantaneous overvoltage flowing into the power line and signal transmission line is limited to the voltage range that the equipment or system can withstand, or the strong lightning strike is discharged into the earth to protect the electronic equipment or system from impact and damage.
2. Things to note when testing lightning protection devices
(1) Testing institutions and personnel must hold certificates to work. Institutions and personnel engaged in lightning protection device testing shall hold a lightning protection device testing qualification certificate and personnel related certificates issued by the Meteorological Bureau. When conducting lightning arrester testing, the working group needs to be led by personnel with engineer or above qualifications. The implementation process of lightning protection device testing must strictly comply with the safety regulations of the inspected unit and the relevant provisions of the quality assurance manual.
(2) The focus of the inquiry is the nature of the lightning protection device. By asking the relevant person in charge of the inspected party about the lightning protection situation, understanding the grounding network, paying special attention to hidden projects such as artificial grounding, and analyzing the probability and consequences of lightning strike disasters in the area protected by the lightning protection device. Inquire about the material, material, layout and construction technology of the grounding body to determine the lightning protection level of the protected area. For the understanding of the grounding body, it is important to ask whether the burial depth of the grounding body and the safe distance from the pedestrian passage can meet the specified requirements.
If the safety distance requirements are not met, whether other safety measures have been taken for protection; it is also necessary to carefully ask whether there is a sufficient safety distance between the artificial grounding body of the party being inspected and the adjacent grounding body. If the safety distance does not meet the standards, whether the grounding grid is equipped with equipotential connections.
High voltage arrester
(3) Check. The detection of lightning protection devices includes two steps: inspection and measurement. Inspection is one of the important work steps. Down conductors and lightning arresters are the focus of lightning protection inspections. First check whether the lightning arrester is corroded, damaged, or whether there are other conductors or wires such as telephone lines, TV signal lines, communication signal lines, power lines, etc. attached. These metal wires have low voltage resistance. Once struck by lightning, lightning current will enter the room along the metal circuit, endangering the lives of equipment and personnel. Therefore, it is strictly prohibited to wrap the arrester, and check whether the material, specifications, layout and construction technology of the arrester meet the requirements of the arrester setting specifications; for commercial buildings, check whether all metal objects on the roof plane are connected at equal potential; various types of flammable and explosive places such as gas stations and liquefied gas stations Whether the pipelines are connected at equal potential when parallel or crossing, whether various transmission pipelines are repeatedly grounded within the specified length, and whether lightning wave intrusion protection measures are set up; it is also necessary to check whether the models of surge protectors at all levels match the protected equipment, whether they can work normally, and whether lightning protection induction measures are in place. Check the material, specifications and construction technology of the down conductor, especially the exposed down conductor, to see if the safety distance between the down conductor and other lines meets the requirements, calculate and determine whether there is a possibility of breakdown causing property and personal casualties, and observe whether there are flammable gas pipes and other metal pipes around it.
(4) Measurement. Before measuring the lightning arrester, you should check whether all testing instruments are in normal condition and whether they are damaged, and ensure that the measuring instruments are in good condition. When measuring, you should first connect the measuring instrument and then retest the data. Data is transferred in a repetitive manner. When the data j is accurate to decimal places, it should be recorded clearly and accurately; the wiring method and working status of the measuring instrument before and after measurement should also be recorded. Fill out the original records carefully and change the original data to meet the stated requirements.
(5) Calculation. It is necessary to calculate the protection range of lightning rods and lightning conductors. The protection range of a single lightning rod on the floor only needs to pay attention to the selection of the rolling ball radius; if a lightning rod is installed on the floor, the floor can be regarded as the ground to calculate the protection range of the lightning rod, and the rod height is the rod length; if there is no lightning rod on the floor, the height of the lightning rod is equal to the length of the lightning rod plus the height of the building. The height of the lightning protection object on the top of the building is the height of the building plus the height of the protector. When calculating the protection range of the lightning rod, observe whether there is any sagging in the middle of the lightning rod. If you calculate the protection range of the middle part, you need to subtract the sagging height. If there are two or more lightning rods for combined protection, the minimum protection height should be higher than the minimum height calculated for a single lightning rod.
3. Regularly inspect lightning protection devices
(1) Improve the testing specifications for lightning protection devices. Laws and regulations stipulate that the meteorological department is the main body in formulating lightning protection testing specifications. All lightning protection testing agencies must actively cooperate with meteorological, construction, fire protection, safety supervision and other departments to jointly establish a joint meeting system for lightning protection and disaster reduction, and conduct regular testing of lightning protection devices in accordance with regulations. to the law.
(2) Strengthen the daily maintenance of lightning protection devices. Regular testing of lightning protection devices can only assess the status of the lightning protection device at that time. Qualified lightning protection device
Lightning arrester manufacturer
