With the implementation of the atmospheric comprehensive observation system construction project, automatic weather stations, as an important component of ground atmospheric detection, have become a source of meteorological information for carrying out refined forecasting and meteorological decision-making services. The geographical environment for the construction of dynamic weather stations is often open and prominent, and the lightning protection settings and their own lightning protection settings are very fragile. Once a direct lightning strike or induced lightning occurs, it will inevitably cause certain damage or losses. This article aims to analyze the causes and related protection methods of lightning strikes on automatic observation equipment at meteorological stations from the perspective of lightning protection.

introduction:

Lightning disasters are unavoidable natural disasters, and lightning activities occur every moment on the earth where humans live. Therefore, it is essential to grasp the laws of its occurrence and development and take necessary preventive measures. Lightning poses a great threat to information and communication systems. There are generally two forms of damage caused by lightning acting on communication systems: one is induced lightning causing damage to equipment, and the other is direct action on equipment through metal wires or connectors causing damage. Statistics show that 30% of communication equipment damage is caused by lightning. Therefore, setting up professional and comprehensive lightning protection facilities for automatic stations has become a very important task.

1、 Characteristic analysis of lightning disasters in automatic weather stations

1. Intensity of lightning overvoltage

According to statistics, the lightning overvoltage on low-voltage transmission lines is below 6 kV, and the current ranges from 3 kA to 10 kA. The induced lightning overvoltage on the communication line is about 5 kV, and the current is several hundred amperes. The 1971 US research report [AD722675] pointed out that electronic computers would malfunction when the magnetic induction intensity reached 7 × 10-8 T during lightning flashes, and permanent damage would occur when it reached 2.4 × 10-6 T. These two numbers are equivalent to the result of a 100 kA lightning current flowing into the ground at 860 m and 83 m.

The radius of electromagnetic effects caused by lightning strikes on the ground that endanger the electronic tube equipment system is about 400 m to 800 m; Is it 800 m~1 for transistor devices? 200 meters; 2 for microelectronic devices? Over 000 meters. If the electronic devices of the automatic weather station are located between 10 m and 100 m from the lightning strike point, the magnetic induction intensity caused by lightning strikes on the power lines is 0.6-2 × 10-5 T; the magnetic induction intensity caused by lightning strikes on the communication lines is on the order of 107-106 T. The former is sufficient to cause errors or damage to microelectronic devices, while the latter may also cause equipment to malfunction, indicating the poor ability of automatic weather stations to resist lightning electromagnetic pulses. Therefore, it is necessary to take lightning protection measures for automatic weather stations.

2. Analysis of lightning intrusion pathways

① Direct lightning strike. Direct lightning strikes directly hit the automatic weather station equipment, causing partial or complete circuit damage to the weather equipment. Due to the installation of lightning protection devices in automatic weather stations, this situation is relatively rare. According to the survey of automatic weather stations in Shantou City and its surrounding areas, no such lightning strike accidents have occurred;

② High voltage pulse. High voltage pulses from electrostatic and electromagnetic induction of lightning induce high voltages ranging from several thousand volts to tens of kilovolts in various cables. This situation usually affects various sensors. Among them, the wind direction sensor, as the instrument with the highest position in the automatic weather station and a large number of semiconductor components, is often prone to lightning strikes; ③ Lightning strikes cause an increase in electrical potential. Causing an increase in ground potential near the lightning strike point, the high potential is introduced into the circuit through the grounding wire of the equipment, resulting in damage to circuit components;

④ Invasion of AC power supply lines. The power supply of the automatic weather station is provided by low-voltage transmission lines. When the power line is struck by lightning, it is introduced into the equipment in the form of traveling waves along the transmission line, causing it to fail or be damaged. When a direct lightning strike strikes a medium to high voltage transmission line, the overvoltage generated is coupled to the secondary through a transformer, resulting in lightning overvoltage on the low voltage transmission line. At the same time, the static and electromagnetic induction of lightning can also induce overvoltage on the low voltage transmission line, which may cause damage to equipment. Due to the connection between the power board and AC power, in the statistics of lightning accidents at automatic weather stations in Shantou City and its jurisdiction, the power board is the equipment with a high probability of failure. Within two consecutive months, two strong lightning strikes occurred at the observation site in Nan'ao County, and the power board inside the collector was also damaged.

2、 Application of lightning protection technology in automatic weather stations

1. Lightning protection grounding

Lightning protection grounding is the primary technical link in lightning protection technology. Whether it is direct lightning strikes or induced lightning strikes, the lightning current must be introduced into the ground. Therefore, if lightning protection engineering is to be reliable and stable, stable grounding devices must be installed. The grounding of the automatic station should adopt a single point grounding method, using a shared grounding grid with a grounding resistance value of ≤ 4 Ω. Both working grounding and protective grounding should be introduced into the grounding grid, with a distance of more than 5 meters from the down conductor to ensure that the entire grounding grid is connected to the grounding grid.

2. External lightning protection

According to the requirements of the regulations, automatic weather stations are mostly located in open areas, which are easily attacked by lightning. Whether the external lightning protection of the automatic station is in place directly affects the safety of its operation. The anti direct lightning arrester is composed of metal components, lightning protection belts, lightning rods, and lightning protection nets. The solar cells and collectors in the Pulandian area should be protected with separate lightning rods. Stations with personnel on duty also need to provide lightning protection for the building where the duty room is located. The observation field, collector, communication line, sensor, and other outdoor equipment can assume that the lightning rod is on the wind pole, calculate its protection range, and this range must strictly comply with the requirements of lightning protection technical specifications. It is particularly important to note that the wind pole itself is made of metal and is a very suitable discharge channel for lightning strikes. If the design and installation of the outdoor grounding network are unreasonable, it may cause damage to all observation equipment due to lightning strikes. Therefore, it is necessary to ensure that lightning protection devices are properly installed in order to smoothly introduce lightning into the underground.

3. Internal lightning protection

In this field, lightning protection should not only consider the protection against induced lightning, as induced lightning can cause voltage overload to electrical equipment along the line, propagate to the equipment through information signals and power lines, and cause lightning damage.

3.1 Lightning induced surge protection.

The losses suffered by electronic and information devices after being struck by lightning are mostly caused by lightning induced surge voltage. These surges enter the interior of electronic components, causing damage to chips, interfaces, or circuits. Therefore, signal lightning protection devices should be installed between signal lines and multi-level protection measures should be adopted. Install signal lightning arresters of matching models in transition zones of different levels. Automatic station network lines should also be equipped with lightning protection devices, especially for collectors, routers, signal transmission systems, etc. Computer network communication generally uses broadband (ADSL) access to the Internet to transmit data. Install corresponding signal lightning arresters according to different requirements, provide at least secondary protection, and ensure proper grounding of computer information system related equipment.

3.2 Lightning protection for power system.

At present, the power supply system of meteorological equipment in Pulandian generally adopts TN-S or TN-C-S system power supply mode, which requires multi-level lightning protection to prevent lightning intrusion from causing damage to the distribution system and related equipment. Install one power supply SPD with a rating of 40 kA or higher at the main incoming line of the power supply. Install a 20 kA power supply SPD between the distribution incoming line in the computer room and the UPS at level 2. Level 3: Install a 10 kA power SPD at the front end of the collector, and install a socket type lightning arrester between each computer power supply and UPS.

3、 Analysis of the Development Prospects of Meteorological Lightning Protection Technology

1. The development direction of meteorological lightning protection technology in prediction and early warning is advancing

Due to the fact that in the process of meteorological lightning protection, neither in-process nor post control can match the reasonable avoidance of lightning attacks that are about to occur beforehand, meteorological lightning protection, as a very important technology for predicting in advance, is an inevitable trend for the improvement of lightning prediction technology and pre warning prediction technology in future development.

2. Continuous reform and innovation of meteorological lightning protection technology

The work of meteorological lightning protection technology cannot be limited to existing achievements, and the shortcomings of the past should also be learned from. Only by drawing on history can we move forward better. History is a mirror that can help people avoid making the same mistakes in the early stage. Only by breaking through existing limitations can we better promote the development of meteorological lightning protection technology. On the road of implementing overall planning, layered implementation, and top-down collaboration in the meteorological industry, it is ensured that the reliability is highly unified and circulated both vertically and horizontally, and resources from all aspects can be coordinated to truly achieve high cooperation and work efficiency, avoiding waste caused by repetitive work.

4、 Conclusion

For modern society with frequent meteorological disasters and individual areas with frequent lightning disasters, how to steadily promote meteorological lightning protection technology work is an important issue to ensure the safety of people's lives and property. We should give full attention to meteorological lightning protection technology work, grasp the key points of meteorological lightning protection technology work, increase investment, ensure that lightning protection work is carried out scientifically and reasonably, with social interests as the goal, so that meteorological lightning protection and even the entire meteorological work can serve economic growth and promote development. Enable meteorological lightning protection technology to fully play its due role and function.