With the advancement of technology, micro-electric equipment has been widely used, urban communication power supply has increased significantly, and urban electromagnetic fields have changed. In particular, microelectronic products generally have low dielectric strength, poor over-voltage tolerance, and are vulnerable to lightning strikes, among which computer networks, Communication command systems and public antennas are the hardest hit areas. Lightning hazards can be divided into three types: direct lightning, inductive lightning and lightning. At present, the disaster caused by direct lightning strikes has been significantly reduced, and with the development of urban economy, the damage caused by inductive lightning and lightning wave intrusion has greatly increased. Lightning rods on general buildings can only prevent direct lightning strikes, while the inductive lightning and pulse voltage generated by powerful electromagnetic fields can sneak into indoors to endanger weak equipment such as televisions, telephones and networked computers.
With the rapid development of radio and television equipment such as television microwave transmission, cable TV, application television, satellite ground station, television transmitter, broadcast transmitter, electronic equipment, computer network, etc., the lightning protection problem has become more and more prominent. To this end, through analysis, lightning mainly invaded radio and television equipment through the following five ways: 1. direct lightning strike; 2, power line intrusion; 3, antenna feeder intrusion; 4, signal line intrusion; 5, ground potential counterattack.
In order to prevent lightning disasters, we must strengthen the protection of radio and television equipment based on the principle of “comprehensive governance, overall defense, multiple protection, and layered fortificationâ€.
1, anti-direct lightning. Since the transmission and reception of broadcast and television signals are mostly installed on high mountains, high-rise buildings or elevated towers, the probability of direct lightning strikes is high. The usual measures are to set up lightning rods of a certain height and attract lightning through the lightning rods. On the flash, then the lightning is transmitted to the ground. The energy of the direct lightning strike is dissipated underground, thus protecting the buildings on the ground.
Due to the defects of the lightning rod, it is necessary to install a responsive electronic lightning rod for various transmitting and receiving antennas protected by the lightning rod and various equipment in the building, to minimize the grounding resistance of the ground, various pipes and metal on the roof. Cable sheaths, billboards, etc. must be connected with thick wires and welded with lightning rods. The building should be equipped with a pressure equalizing ring. The vertical distance of the ring should not exceed 12 meters. All the down wires, the overhead metal entering and leaving the building. Pipes, metal structures and equipment of buildings shall be connected to the ring to minimize the damage caused to the broadcast television equipment caused by an induced lightning strike caused by lightning strikes.
2. Power line lightning protection. Since the lightning energy is mainly concentrated in the low frequency band of less than 40KHz, the power frequency line of 50KHz power supply is most likely to couple harmonics with the maximum energy harmonic component near the power frequency, and the AC power grid is large and wide, and the lightning wave is relatively easy to be from the power source. The line route destroys electrical and electronic equipment.
The general practice is to connect 1-3 three-phase three-phase, single-phase power supply arresters in the power transformer secondary, machine room power distribution cabinet, equipment switchboard, equipment power supply line, and carry out multi-level shunting of lightning and enter the ground. When the lightning wave invades along the power line, the resistance of the arrester drops to a very low level. Near the short circuit state, the lightning current flows into the ground from here, which is similar to the intrusion channel that intercepts the lightning. After the lightning has passed, it will recover instantaneously and short circuit to the ground, without affecting the normal power supply.
3, the antenna feeder line lightning protection. User antennas, shared antennas, TV receiving satellite earth stations, TV transmitters, etc. Due to the demand characteristics of transmitting and receiving signals, most of the antenna feeder systems are installed on high-rise buildings or overhead towers. The probability of lightning strikes introduced by electronic equipment from the antenna feeder system is very high. .
The traditional "air gap", "gas discharge tube", "zinc oxide varistor" and their combined arrester can play a role in lightning protection of the antenna feeder line, but in terms of operating frequency band, response time and power consumption. limitation. Since the main energy of the lightning current shock wave is distributed in the frequency domain below 40 kHz, and the energy of the broadcast television signal is distributed in the frequency domain above several hundred kHz, the high-low-pass filter combination network should be used to form the high-low-pass filter combination network to distinguish the lightning shock wave and the useful signal. Separate, solve the problem of broadband, high power, low loss, fast response, long-term troubled photoelectric anti-lightning.
4. Signal line lightning protection. In radio and television systems, antenna amplifiers, application televisions, television cameras, fax machines, television receivers, computers, telephones, etc., often use coaxial information cables, ribbon cables and other metal information transmission lines, and timely buried transmission cables are also often lightning strike failure.
When lightning electromagnetic pulse interference occurs, because the conductor has large inductance and capacitive reactance in the alternating electromagnetic field, a large potential difference is generated, and the lightning wave generates a standing wave when it propagates on the cable surface. The device can form a strong interference and often cause an overvoltage to damage the device through the interface.
The general method is to strengthen the shielding of the cable, the metal skin outside the cable is well grounded, and through the series signal point arrester, the information is separated from the lightning channel, and the lightning intruding wave is cut off at the entrance of the device.
Since the computer operating voltage is low, usually 5-12V, the potential difference generated between the units of data processing must be very small, except that the signal lightning arrester is installed at the interface to protect the signal channel from overvoltage. The length of the grounding wire to which the high-frequency signal is grounded needs to be noticed. When it is affected by the resonance and the standing wave, it is close to the resonant frequency, and the conductor exhibits a great inductive reactance, which cannot provide an effective connection between the two units of the data processing device. Isopic effect, when the length of the conductor is equal to 1/4 of the harmonic wavelength or an odd multiple of the 1/4 wavelength, the conductor has an open state at both ends, so the length of the high-frequency grounding ground must not generate standing waves As a condition.
5, anti-ground potential counterattack. Because the lightning rod is introduced into the ground, the impact overvoltage of more than 1KV is generated at the grounding, and the impact breakdown field strength of the soil is about 200-1000 KV/m, and the average value is 600 KV/m. Therefore, the grounding body is 3m. The soil inside will generate a large new inrush current. Further, it will be affected to varying degrees due to the undercurrent of the soil and the sensing of various underground pipes and conductors.
Usually, the power ground, the working ground, the signal ground, and the outer casing of the electronic device are separated, and the purpose is to eliminate a possible ground noise source and obtain a satisfactory pure potential.
In order to prevent the ground potential counterattack, the current view is that: First, the lightning protection ground, the working ground, the protection ground and other systems are connected to form a grounding grid to form an equipotential. In some places, such as microwave stations, medium wave launchers, TV transmitters, and launchers, each has a grounding device. It also needs to be equipotentially connected to become a whole, so that the ground potential rises when lightning enters the ground. To avoid counterattacks. However, such a unified grounding, for transmitters and other microelectronic devices, when there is no lightning, the ground wave interference will occur. To solve the two problems of counterattack and interference at the same time, the anti-interference work can be set separately.
6. Grounding. Firstly, a low-voltage isolation lightning arrester is installed between the working ground and other grounding. When the potential difference between the two places exceeds the protection value, it is turned on instantaneously and connected to the ground potential. When the potential difference between the two grounds is lower than the protection value, The ground is restored to isolation.
Secondly, between the various ground lines and ground lines of the equipment room and the main steel bars of the building structure, effective ringing must be carried out, that is, all the common grounding systems are used. When the lightning causes the high potential of the ground potential to counterattack, the whole building and the room presentation system The equipotential, the lightning protection system presents a working state to ensure the safety of the network system.
Due to the randomness of lightning, the mechanism of formation is very complicated, and the manifestation of lightning is various. Therefore, the current level of lightning protection technology is limited to any single lightning protection device can not guarantee the protection of all protection objects in a specific space. Ray safety, lightning protection technology needs to be further improved.
ZGAR bar 2000 Puffs
ZGAR electronic cigarette uses high-tech R&D, food grade disposable pod device and high-quality raw material. All package designs are Original IP. Our designer team is from Hong Kong. We have very high requirements for product quality, flavors taste and packaging design. The E-liquid is imported, materials are food grade, and assembly plant is medical-grade dust-free workshops.
Our products include disposable e-cigarettes, rechargeable e-cigarettes, rechargreable disposable vape pen, and various of flavors of cigarette cartridges. From 600puffs to 5000puffs, ZGAR bar Disposable offer high-tech R&D, E-cigarette improves battery capacity, We offer various of flavors and support customization. And printing designs can be customized. We have our own professional team and competitive quotations for any OEM or ODM works.
We supply OEM rechargeable disposable vape pen,OEM disposable electronic cigarette,ODM disposable vape pen,ODM disposable electronic cigarette,OEM/ODM vape pen e-cigarette,OEM/ODM atomizer device.
ZGAR bar 2000 Puffs Disposable Vape, bar 2000puffs,ZGAR bar 2000 Puffs disposable,ZGAR bar 2000 Puffs,ZGAR bar 2000 Puffs OEM/ODM disposable vape pen atomizer Device E-cig
Zgar International (M) SDN BHD , https://www.sze-cigarette.com