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In recent years, frequent lightning strikes at gas stations have caused major hazards and losses to the people’s lives and property, and lightning protection at gas stations cannot be delayed. The lightning protection at the gas station is different from the lightning protection at other places. The following is a brief introduction to the features and measures of the lightning protection at gas stations:
First, gas stations usually have the following characteristics:
(1) Geographical location: The refueling and refueling stations are usually located in open areas of urban areas or in the outskirts of the city, suburbs, mountains, villages, highways, etc.;
(2) Power supply system: The 380V AC line of a general gas station is connected to an overhead line to be introduced into the building near the station area. Some refueling stations are connected by overhead lines via a 10KV power line and then buried in the building after the transformer. . In rural areas and mountain areas, there are sometimes no buried measures, so it is very easy to induce lightning electromagnetic pulses.
(3) Implementation conditions: These fueling and refueling station buildings often do not have the lightning protection facilities (including external lightning protection, internal lightning protection and ground network, etc.) that meet the requirements in both urban and rural areas. In addition, the operating floor area of ​​refueling and filling stations is generally very small, which is inconvenient for the implementation of multi-level lightning protection programs;
Second, protective measures
From the above several problems, we must adopt the protective measures of the system for lightning protection of vehicle refueling and refueling stations: such as lightning, diversion, grounding, voltage equalization, integrated wiring, installation of lightning protection devices and other comprehensive measures.
(1) Grounding: Grounding shall be made around the building as a ring-closed grounding device. In each lead-off line, 2-3 vertical grounding poles shall be arranged. The vertical grounding pole shall be 2.5m long and the depth of burial shall be 0.7m or less. The function is to reduce the impact grounding. Resistance and fixed ring closure device, grounding network should be in the tank unloading site, refueling machine installation, distribution board entrance, buried tank snorkel welding grounding branch, for the above equipment for grounding.
The grounding device should be shared with the grounding resistance value of the grounding resistance value of the refueling refueling station for lightning protection grounding, antistatic grounding, working grounding of electrical equipment, protective earthing, grounding of electronic systems, and grounding of lightning protection devices.
(2) Connection flash: According to the comprehensive analysis of the meteorological, topographical, geomorphological and ambient conditions of the vehicle refueling station, when the refueling station is likely to suffer direct lightning strikes, a lightning protection zone should be installed on the roof of the refueling station. (Net) Flashing.
(3) Pressure equalization: All the metal pipes entering and exiting the ring grounding device after refueling the gas station buildings as ring grounding devices. The metal sheath of the cable and the conductor protection tube should all be connected at the intersection with the ring grounding device. All equipment and components that need to be grounded in gas stations, such as tanks, fuel dispensers, ventilation pipes, switchboards, switchboards for electronic systems, switches, lamps, etc., must be connected to the grounding network so as to be adjacent to metal conductors and equipment. The potentials (voltages) are equal. Prevent lightning from counterattacking sparks and maintain operator's electric shock to protect equipment and personal safety. Adjacent metal conductors and equipment are bridged by conductors.
(4) Diversion: After refueling and refueling stations are installed with lightning protection strips (nets) on their roofs, column steel reinforcement or laying of flat steel shall be used as the deflector, so that the lightning current can be guided and leaked into the earth by multiple paths. Lightning induced electric potentials or currents on nearby conductors or wires and cables shall be routed as much as possible and be laid out evenly around the fueling and refueling station. The underground part shall be welded to the grounding wire.
(5) Reasonable wiring: When the roof of a vehicle refueling and refueling station is equipped with lightning protection (network) lightning, the power distribution line and the wiring of the electronic system should be far away from the down conductor of the lightning protection zone, and it is better to be apart from each other. Above 2m, otherwise the steel pipe shall be reinforced and shielded.
(6) Installation of lightning protection device: The lightning protection device installed in the distribution system must meet the requirements of lightning protection category, pay attention to the exposed electrical equipment should not be too prominent, the metal bracket should be reliably grounded, the power line should be shielded and grounded, and should be at the switch When installing surge protectors, attention should be paid to the protection of thunder and lightning electromagnetic pulses in information systems.
Some refueling and refueling stations installed a first-grade lightning protection device on the power supply line. However, due to the insufficient number of stages, the artificial grounding body has too large a resistance value, the grounding line is too long or the connection is not reliable. The lightning protection effect actually has nothing to do with the lightning protection device. Gas stations are fire-fighting sites. It is recommended to install explosion-proof lightning protection devices. The selection of lightning protection devices must also be based on the selection of qualified products. We must not install inferior lightning protection products and strictly follow the standard regulations for installation and construction.