Among them, the surge of the metal pipeline and the ground potential counterattack of the ground channel are the main causes of the damage of the electronic information system. Its most visible form of damage is damage caused on the power line. Therefore, it must be used as the focus of anti-expansion. As thunder and lightning penetrate the electronic information system, lightning protection will be a systematic project. The centerpiece of lightning protection is divergence and balance.
1. The bleed is to discharge the lightning and lightning electromagnetic pulse energy through the earth, and should comply with the principle of hierarchy, that is, to discharge excess energy into the ground as much as possible and as far as possible before introducing it into the communication system; The established level of lightning protection discrimination weakens the energy of lightning. The lightning protection zone is also called electromagnetic compatibility zone. It divides the environment into several areas according to the intensity of feelings of lightning, lightning and electromagnetic pulses according to people, objects, and information systems. In the LPZOA area, all objects in the area may be directly struck by lightning. Therefore, all the special objects may lead away all the lightning currents, and the electromagnetic field in the area does not decay. In the LPZOB area, objects in the area could not be directly struck by lightning, but the electromagnetic field in the area did not decay. In LPZ1 area, objects in this area cannot be directly struck by lightning, and the current flowing to each conductor is further reduced than in LPZOB area. The electromagnetic field attenuation and effect depend on the overall shielding measures. Subsequent lightning protection zones (LPZ2 zone, etc.), if it is necessary to further reduce the guided current and electromagnetic field, shall be introduced into the subsequent lightning protection zone. The requirements for the protection zone shall be selected according to the environmental zone required by the system to be protected and the requirements for the lightning protection zone must be continued. condition. The higher the protection zone number, the lower the expected interference energy and interference voltage. In modern lightning protection technology, the installation of lightning protection zones is of great significance. It can guide us in the implementation of technical measures such as shielding, grounding, and other power connections.
2. Equilibrium is to keep the potential difference of each part of the system not enough to cause damage, that is, the potential of all the metal conductors in the system environment and the system itself remains substantially equal in the transient phenomenon, which is essentially based on equal voltage equipotential bonding. A potential compensation system consists of a reliable grounding system, metal wires for equipotential bonding, and equipotential bonding (lightning protection). This potential compensation system can be quickly protected in the presence of transients for a very short time. An equipotential is established between all conductive components in the area where the system is located. These conductive components also include active wires. Through this complete potential compensation system, an equipotential region can be formed in a very short time. This region may have a potential difference of tens of kilovolts with respect to the distant region. It is important that there is no significant potential difference between all conductive parts within the area where the system to be protected is located.
3. The lightning protection system consists of three parts, each part has its important role, there is no alternative. The external protection consists of a lightning arrester, a down conductor, and a grounding body. It can direct most of the lightning energy into the underground discharge. Transition protection, consisting of reasonable shielding, grounding, and routing, can reduce or block the induction introduced through each intrusion channel. Internal protection consists of voltage equalization and overvoltage protection to balance the system potential and limit the overvoltage amplitude.
Sintered NdFeB magnets are prepared by the raw materials being melted in a furnace, cast into a mold and cooled to form ingots. The ingots are pulverized and milled; the powder is then sintered into dense blocks. The blocks are then heat-treated, cut to shape, surface treated and magnetized.
As of 2012, 50,000 tons of neodymium magnets are produced officially each year in China, and 80,000 tons in a "company-by-company" build-up done in 2013. China produces more than 95% of rare earth elements, and produces about 76% of the world's total rare-earth magnets.
Neodymium magnets are graded according to their maximum energy product, which relates to the magnetic flux output per unit volume. Higher values indicate stronger magnets and range from N35 up to N52. Letters following the grade indicate maximum operating temperatures (often the Curie temperature), which range from M (up to 100 °C) to EH (200 °C).
Sintered Nd2Fe14B tends to be vulnerable to corrosion, especially along grain boundaries of a sintered magnet. This type of corrosion can cause serious deterioration, including crumbling of a magnet into a powder of small magnetic particles, or spallingof a surface layer.
This vulnerability is addressed in many commercial products by adding a protective coating to prevent exposure to the atmosphere. Nickel plating or two-layered copper-nickel plating are the standard methods, although plating with other metals, or polymer and lacquer protective coatings are also in use.
Neodymium magnets have replaced alnico and ferrite magnets in many of the myriad applications in modern technology where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets for a given application. Some examples are:
ï‚·Head actuators for computer hard disks
ï‚·Magnetic resonance imaging (MRI)
ï‚·Mechanical e-cigarette firing switches
ï‚·Locks for doors
ï‚·Loudspeakers and headphones
ï‚·Magnetic bearings and couplings
ï‚·Electric motors:
ï‚·Cordless tools
ï‚·Servomotors
ï‚·Lifting and compressor motors
ï‚·Synchronous motors
ï‚·Spindle and stepper motors
ï‚·Electrical power steering
ï‚·Drive motors for hybrid and electric vehicles. The electric motors of each Toyota Prius require 1 kilogram (2.2 pounds) of neodymium.
ï‚·Actuators
ï‚·Electric generators for wind turbines (only those with permanent magnet excitation)
ï‚·Direct-drive wind turbines require c. 600 kg of PM material per megawatt
ï‚·Turbines using gears require less PM material per megawatt
ï‚·Toys
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