Stadiums and gyms are crowded places. It is necessary to take all-round lightning protection measures and carry out effective lightning protection projects to ensure the lightning protection safety of the stadiums.
First, the lightning protection design of stadiums
(1) Direct lightning protection
In the lightning protection design of the stadium, the favorable conditions of the building structure should be fully utilized. The metal roof of the stadium, the steel members in the steel structure, and the steel bars in the reinforced concrete are effectively connected by welding, and the entire stadium becomes a Faraday cage. The lightning protection system is designed to prevent counterattack on human body when lightning strikes.
(2) Equipotential connection
The parts that can be touched by people in the stadium are connected with equipotentials accordingly. The equipment in the venue is reliably connected to the Faraday cage to ensure the transient equipotential between objects at the moment of lightning.
(3) Electronic information system
The electronic information system, power supply, etc. in the venue must be equipped with a surge protector, which is protected by more than three levels of power supply. The signal line should select the suitable signal surge protector according to the characteristics of the equipment to be protected. All surge protectors must have good energy coordination and reliable grounding.
Second, regularly carry out lightning protection tests
Lightning protection detection is an important part of lightning protection safety management. The stadium should be tested at least once a year for unconventional lightning protection. The key lightning protection devices to be tested are:
(1) Ground resistance
According to the "Guidelines for Measuring Soil Resistivity, Grounding Impedance and Ground Potential of Grounding System Part 1: Conventional Measurements" GB/T17949.1-2000 Chapter 7 and Chapter 8 provide soil resistivity and grounding impedance measurement methods, respectively Using the isometric method (also known as the Wenner method) and the potential drop method, the soil resistivity and grounding resistance values in the vicinity of the grounding device are measured.
(2) Equipotential connection
Use an equipotential tester to measure the transition resistance between the device under test and the reference point based on the reference point. The total equipotential connection of the building and the local equipotential connection of electrical and electronic equipment are reflected by the value of the transition resistance. Depending on the object and location of the test, the reference point of the test should be selected close to the device under test.
Reference points for potential connection tests: building total equipotential bonding terminal (MEB) or ground test terminal, embedded parts of electronic system room, ground bus or local equipotential terminal (LEB) in strong and weak electric shaft, power distribution The PE row of the box and the electrical equipment on the roof of the building are reserved for grounding.
(3) On-site inspection of SPD
SPD on-site inspection mainly includes visual inspection and on-site testing of some parameters.
1. Visual inspection of SPD
The surface should be flat, smooth, free of cracks and burning marks or deformation, etc. The SPD logo should comply with the relevant regulations and be clearly marked; check whether the SPD has a status indicator, and if so, confirm that the status indication should be consistent with the manufacturer's instructions ; Check if the built-in or backup disconnector of SPD is in normal state.
2. On-site test of SPD, use the lightning protection element tester to test the voltage and leakage current of the surge protector, and judge whether the surge protector is degraded and failed according to the measured data.