Zinc oxide arrester YIW5-7.6/19
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Harbin arrester manufacturers wholesale, Heilongjiang arrester manufacturers direct sales, Arrester Y1W5-7.6/19FZ-10KV valve arrester FZ-15KV valve arrester FZ-35KV valve arrester HY1.5W-0.28/1.3 high and low voltage arrester HY1.5W-0.5/2.6 high and low voltage arrester HY1.5W-4.8/12 high and low voltage arrester RW11-10F/200A drop out fuse HRW3-10/100A drop out fuse RW5-35/100A drop out fuse Y5WR-7.6/27 high and low voltage arrester YH5WR-84/221 high and low Voltage arrester YH5WR-90/236 HV and LV arrester YH10WZ-100/248 HV and LV arrester Y3W1-12.7/31 HV and LV arrester Y1W5-7.6/19 HV and LV arrester Y1W1-7.6/19 HV and LV arrester Y2.5W1-12.7/31 HV and LV arrester Y3W-0.5/2.6 HV and LV arrester YH10WZ-192/500 HV and LV arrester YH10WZ-200/520 HV and LV arrester YH10WZ-204/532 HV and LV arrester YH10WZ-216/562 HV and LV arrester HY10WX-120/334TL HV and LV arrester HY10WZ-108/281 HV and LV arrester YH10WS-126/268 HV and LV arrester YH10WS-126/268 HV and LV arrester Y10WS-200/520W HV and LV arrester Y10WS-100 HV and LV arrester Y10WS-51/134 HV and LV arrester Y10W-100/260W1 HV and LV arrester YH5CX2-42/120N HV and LV arrester HY5CX-42/152 HV and LV arrester HY5CZ1-42/124 HV and LV arrester Arrester, also known as surge arrester, is an electrical device that can release lightning or simultaneously release the operating overvoltage energy of the power system, protect electrical equipment from the harm of transient overvoltage, cut off the aftercurrent and prevent the system from grounding short circuit. The lightning arrester is usually connected between the live conductor and the ground, and connected in parallel with the protected equipment. When the overvoltage value reaches the specified action voltage, the arrester will act immediately, flow the charge, limit the overvoltage amplitude, and protect the insulation of equipment; After the voltage value is normal, the arrester will quickly return to its original state to ensure the normal power supply of the system. Check the wonderful atlas catalogue Lightning arrester origin Lightning arrester principle Lightning arrester classification function and characteristics Main parameters Lightning arrester related standards Zinc oxide lightning arrester Use lightning arrester daily operation maintenance Famous lightning arrester brand SPD Use lightning arrester principle Expand lightning arrester origin Lightning arrester principle Lightning arrester classification function and characteristics Main parameters Lightning arrester related standards Zinc oxide lightning arrester Use lightning arrester daily SPD, a well-known lightning protection brand in operation and maintenance, selects the principle of lightning arrester to edit. The original lightning arrester in this section is a sheep horn gap, which appeared at the end of the 19th century. It is used for overhead transmission lines to prevent power failure caused by lightning damage to equipment insulation, so it is called "lightning arrester". In the 1920s, there appeared aluminum Ayer shield arrester, oxide film Ayer shield arrester and pellet Ayer shield arrester. In the 1930s, tube type ElShield arrester appeared. In the 1950s, silicon carbide Al Shield arrester appeared. In the 1970s, metal oxide Ayer Shield arrester appeared. The modern high-voltage ElShield arrester is not only used to limit the overvoltage caused by lightning in the power system, but also used to limit the overvoltage caused by system operation. Edit the lightning arrester principle in this section. The lightning arrester is the equipment that protects the substation equipment from lightning shock wave. When the lightning impulse wave transmitted to the substation along the line exceeds the protection level of the arrester, the arrester will discharge first, and the lightning current will be safely introduced to the ground through good conductors. The grounding device will limit the lightning voltage amplitude below the lightning impulse level of the protected equipment, so that the electrical equipment will be protected. Arrester Arrester can be divided into the following categories according to its development sequence: protective gap, which is a simpler form of arrester; Tubular arrester is also a protection gap, but it can self extinguish the arc after discharge; Valve type arrester - it divides a single discharge gap into many short series gaps, and increases the nonlinear resistance to improve the protection performance; Magnetic blow arrester - magnetic blow spark gap is used to improve arc extinguishing ability, and also has the ability to limit internal overvoltage; Zinc oxide arrester - it makes use of the ideal volt ampere characteristic of zinc oxide valve plate (extremely nonlinear, that is, it has a low resistance characteristic at high current, which limits the voltage on the arrester, and it has a high resistance characteristic at normal power frequency voltage), has the advantages of no gap, no aftercurrent, low residual voltage, and can also limit internal overvoltage, and is widely used. Edit the lightning arrester classification in this section. There are high-voltage and low-voltage lightning arresters. This section introduces the lightning arresters (SPD) in low-voltage distribution system The classification of different types of lightning arresters may be in front of us. From the combination structure; There are several types of lightning arresters on the market today: 1) gap type -- open gap, closed gap 2) discharge tube type -- open discharge tube sealed discharge tube 3) varistor type -- single chip, multi chip 4) suppression diode type 5) varistor/gas discharge tube combination type -- simple combination Complex combination 6) Silicon carbide can be divided into open circuit arrester, short circuit arrester or switch type, and voltage limiting type according to their protection properties. According to their working conditions (installation form), they can also be divided into parallel arrester and series arrester. 2. Structure and characteristics of arrester 2.1.1 Operating principle of open gap arrester gap arrester: based on arc discharge technology, when the voltage between electrodes reaches a certain level, air arc will be broken down to discharge on the electrode. Advantages: strong discharge capacity, large flow (up to 100KA), small leakage current, good thermal stability; disadvantages: high residual voltage, slow response time, and continuous flow process characteristics: because metal electrodes bear large current during discharge, it is easy to cause metal sublimation, so that the formation of metal coating in the discharge chamber affects the start and normal use of the arrester. The production of discharge electrode is mainly concentrated in some foreign arrester manufacturers, and the main component of electrode is tungsten alloy. Engineering application: the arrester of this structure is mainly used in the power system as a Class B arrester. However, due to the reason of the arrester itself, it is easy to cause fire, and after the arrester acts (flies out), it leaves the switchboard and other accidents. It is suitable for various power distribution systems according to different models. The installation distance must be considered when installing the project to avoid unnecessary losses and accidents. 2.1.2 Closed gap arrester There is a multilayer graphite gap arrester in the domestic market. This arrester mainly uses the continuous discharge of multilayer gap, and each layer of discharge gap is insulated from each other. This lamination technology not only solves the problem of continuous current, but also discharges layer by layer, virtually increasing the flow capacity of the product itself. Advantages: the discharge current is large, the test value is 50KA (actual measured value), the leakage current is small, there is no continuous current, there is no arc leakage, and the thermal stability is good. Disadvantages: the residual voltage is high, and the reaction time is slow. Process characteristics: graphite is the main material, and the product uses all copper coating to solve the heat dissipation problem of the arrester during discharge. There is no subsequent current problem, and the major feature is that there is no arc, And the residual voltage is much lower than that of open gap arrester. Engineering application: this type of arrester is used in various B and C occasions, and the arc problem is not considered when compared with the open gap. According to different models, this product is suitable for various power distribution systems. 2.2 Discharge tube arrester 2.2.1 Open discharge tube arrester Open discharge tube arrester is essentially the same product as open gap arrester, both belong to air arrester. However, compared with the gap arrester, its current carrying capacity is reduced by one level. Advantages: small volume, strong flow capacity (10-15KA), small leakage current, no arc blowout; disadvantages: high residual voltage, poor consistency of continuous flow products (starting voltage, residual voltage), slow response time 2.2.2 Closed gas discharge tube, also known as inert gas discharge tube, is mainly filled with inert gas, and the discharge mode is gas discharge, The purpose of one-time discharge of current is achieved by breaking through the gas. Generally, there are two types of structures: 2-pole and 3-pole. The appearance is similar to the above figure. Advantages: small volume (the gas tube can be very small), large flow rate and no arcing disadvantages: poor product consistency (starting voltage and residual voltage), high continuous current and residual pressure process characteristics: the air discharge tube is still an open product, and it is not guaranteed that no spark will be ejected from the pressure discharge hole when working. The gas discharge tube is a sealed structure, and generally has two pole and three pole improved structure forms, Generally, the 3-pole has a thermal protection device (short-circuit device). When the discharge tube works, the temperature exceeds a certain range, and the short-circuit device starts to make the discharge tube conduct as a whole. To prevent the explosion of high pressure devices in the discharge tube due to high temperature. Engineering application: general air discharge tubes are rarely used now, while gas discharge tubes are now widely used in signal lightning protection devices. Different models are also used on power arrester. 2.3 Zinc oxide resistance arrester 2.3.1 Single varistor arrester Single varistor arrester was invented and used by Japan in the 1980s. Until now, the use rate of single chip sensitive resistor is also higher among lightning arresters. The working principle of varistor arrester is to use the nonlinear characteristics of varistor. When the voltage does not fluctuate, zinc oxide presents a high resistance state. When the voltage fluctuation reaches the starting voltage of the varistor, the varistor quickly presents a low resistance state, limiting the voltage to a certain range. 2.3.2 Multiple varistor surge arresters are produced on the premise that the flow rate of a single varistor is always not ideal (generally, the discharge current of a single varistor is 20KA 8/20uS). Multiple varistor combination surge arresters mainly solve the problem that the flow rate of a single varistor is small, which can not meet the use of Level B occasions. The generation of multiple varistors fundamentally solves the problem of the flow rate of varistors. Advantages: large current capacity, low residual voltage, fast reaction time (≤ 25ns), no following current (freewheeling current) Disadvantages: large leakage current, fast aging speed. General process characteristics of thermal stability: most adopt building block structure. Engineering application: Varistor arresters are widely used in B, C, D and signal arresters according to different structures. However, the problem to be solved is that some products have combustion phenomenon in the project, so attention should be paid to the enclosure materials used by the manufacturer when selecting the product type. 2.4 Suppressing diode lightning arrester Suppressing diode lightning protection products are mainly used in a large number of network and other signal lightning protection products, and the main components used are P * KE (avalanche tube) and other products. The working principle is based on the reverse breakdown protection of PN junction. Advantages: low residual voltage, high action accuracy, fast response time, no afterflow, small volume Disadvantages: small flow rate 2.5 Varistor/gas discharge tube combination 2.5.1 Simple combination arrester Typical structure of the combined arrester is N-PE structure. Compared with the arrester with a single structure, this arrester combines the advantages of two different products and reduces the disadvantages of a single device. Advantages: large flow rate, fast response time Disadvantages: relatively high residual voltage Engineering application: lightning arrester used only in N-PE system is suitable for areas with large voltage fluctuation. 2.5.2 Complex combined arrester This arrester gives full play to the advantages of various components, and generally uses a large number of varistors and gas discharge tubes in structure. The arrester with this structure generally has high current carrying capacity and low residual voltage. The lightning arrester with this structure is also called integrated lightning arrester in the industry. Advantages: large flow rate, fast response time, low residual voltage, no afterflow, good thermal stability, disadvantages: no sound alarm, no counter, process characteristics: the circuit structure of the integrated arrester is compact, giving full play to the characteristics of zinc oxide resistance, and combining the advantages of the gas discharge tube with relatively high current capacity. More zinc oxide resistors are used in the circuit to improve the current carrying capacity of the overall arrester, and gas discharge tubes are used as standby discharge channels. Based on this perfect circuit structure, the service life of the arrester is greatly improved. Engineering application: integrated arrester is widely used in various installation environments of B, C and D according to different models. Due to the integrated design, it is more suitable for use in occasions without installation distance. (The short distance between the three levels of B, C and D modular lightning arresters is more than 10M according to IEC regulations) 2.6 Silicon carbide arrester (valve type arrester) Silicon carbide arrester is mainly used for high-voltage power lightning protection. At present, it is still the power lightning protection product with high utilization rate in the power system. The picture shows the surge protector for AC power supply 2.7 antenna fed arrester coaxial arrester network signal wireless transmission and interface equipment protection; Protection of industrial control signal wireless transmitting and receiving equipment; Protection of satellite TV receiving equipment; Monitoring signal wireless transmitting and receiving equipment protection; Protection of other wireless communication equipment; The use of protection of other RF signal equipment. 2.8 Video signal lightning arrester Video signal lightning arrester DC monitoring system lightning arrester is mainly used for all-round protection of power supply and signal system, and is an integrated multi-function surge protector. It is suitable for surge protection of camera power supply, video, audio and PTZ control lines. It has the characteristics of large flow, low limiting voltage, fast response speed, convenient installation, etc., and can fully protect the monitoring equipment with newer technology. 2.9 Power network two in one lightning arrester Two in one lightning arrester is applicable to the lightning surge protection of the power line and network line of the network camera and wireless remote control camera at the front end of the monitoring system. ◆ It can provide integrated and multi-functional surge protection for the power line and network line of 220V power supply network camera. ◆ The power supply and network of the monitoring camera shall be designed with integrated surge prevention to effectively balance the potential difference of each line. ◆ It can effectively prevent equipment damage caused by instantaneous increase of potential difference between power supply and network lines. ◆ Imported lightning protection devices are adopted, with large flow, low residual voltage, fast response speed and long service life. ◆ Integrated, small size, simple wiring and convenient installation. Edit the function and characteristics of this section. The function of the arrester is to protect various electrical equipment in the power system from lightning overvoltage, switching overvoltage, and power frequency transient overvoltage. The types of lightning arresters mainly include protective gap, valve type lightning arrester and zinc oxide lightning arrester. The protection gap is mainly used to limit atmospheric overvoltage, and is generally used for protection of power distribution system, lines and incoming section of substation. Valve type lightning arrester and zinc oxide lightning arrester are used for the protection of substations and power plants. In 500KV and below systems, they are mainly used to limit atmospheric overvoltage. In EHV systems, they are also used to limit internal overvoltage or as backup protection for internal overvoltage. Edit the main parameter 1. Nominal voltage Un: the rated voltage of the protected system is consistent. In the information technology system, this parameter indicates the type of protector that should be selected, and it marks the effective value of AC or DC voltage. 2. Rated voltage Uc: can be applied to the designated terminal of the protector for a long time without causing the characteristic change of the protector and activating the large effective voltage value of the protective element. 3. Rated discharge current Isn: when the standard lightning surge with the waveform of 8/20 μ s is applied to the protector for 10 times, the larger peak value of the surge current withstood by the protector. 4. Large discharge current Imax: the peak value of large impulse current withstood by the protector when the standard lightning impulse with the waveform of 8/20 μ s is applied to the protector once. 5. Voltage protection level Up: the larger value of the protector in the following tests: the tripping voltage with 1KV/μ s slope; Residual voltage of rated discharge current. 6. Response time tA: the action sensitivity and breakdown time of special protection elements mainly reflected in the protector. The change within a certain time depends on the slope of du/dt or di/dt. 7. Data transmission rate Vs: indicates how many bit values are transmitted in one second, in bps; It is the reference value for correct selection of lightning protector in the data transmission system. The data transmission rate of lightning protector depends on the transmission mode of the system. 8. Insertion loss Ae: voltage ratio before and after insertion of the protector at a given frequency. 9. Return loss Ar: represents the proportion of front wave reflected at the protection equipment (reflection point), and is a parameter that directly measures whether the protection equipment is compatible with the system impedance. 10. Large longitudinal discharge current: refers to the peak value of large impulse current withstood by the protector when each line applies standard lightning surge with a waveform of 8/20 μ s to the ground once. 11. Large transverse discharge current: the peak value of large impulse current withstood by the protector when a standard lightning wave impulse with a waveform of 8/20 μ s is applied between the lines. 12. Online impedance: refers to the sum of circuit impedance and inductance flowing through the protector under the nominal voltage Un. It is often referred to as "system impedance". 13. Peak discharge current: there are two types: rated discharge current Isn and large discharge current Imax. 14. Leakage current: refers to the DC current flowing through the protector under 75 or 80 nominal voltage Un. Edit the relevant standards of lightning arrester in this section Common executive standards of lightning arrester (requirements vary from country to country): IEC61643-1 GB18802.1-2002.UL1283Filter, UL1449.2nd.Edition, GB11032-2010, IEC60099-4.IEEE.C62.11 The current lightning protection system in China is the Technical Code for Lightning Protection of Building Electronic Information System (GB50343-2004) formulated by the Ministry of Construction of the People's Republic of China on March 1, 2004 And GB50057-2010 Code for Design of Lightning Protection of Buildings implemented by the Ministry of Construction of the People's Republic of China on October 1, 2011. IEC623051-2006 Lightning protection IEC/TR61400-24-2002 Wind turbine generator system. Part 24: Lightning arrester IEC61400-24IEC60364-5-54-2002 Electrical facilities of buildings. Part 5-54: Selection and installation of electrical equipment. Grounding measures, protective conductors and protective jumper IEC60364-5-54IEC60099 Lightning arrester GB15599-1995 Safety code for lightning of petroleum and petroleum facilities GB50057-2010 Design code for lightning protection of buildings (with article description) (2010 version) GB50343-2004 Technical code for lightning protection of building electronic information system (with article description) GB/T19271-2003 Protection against lightning electromagnetic pulse GB/T19663-2005 Protection against lightning electromagnetic pulse GB/T19663-2005 Terminology for lightning protection of information systems GB/T19856-2005 Lightning protection GB/T21431-2008 Technical code for detection of lightning protection devices in buildings GB/T21714-2008 Lightning protection GB/T2900.12-2008 Electrotechnical terminology Lightning arrester Low voltage surge protective devices and components GB/T7450-1987 Guidelines for lightning protection of electronic equipment GJB5080-2004 Design and use requirements for lightning protection of military communication facilities GJB1210-1991 Implementation of grounding bonding and shielding design GJB2269-1996 Technical requirements for lightning protection of rear ammunition warehouse Edit seven characteristics of zinc oxide arrester in this section: 1 The large current carrying capacity of zinc oxide arrester is mainly reflected in its ability to absorb various lightning overvoltage, power frequency transient overvoltage and switching overvoltage. The current carrying capacity of the zinc oxide arrester produced by Chuantai fully meets or even exceeds the requirements of national standards. The line discharge level, energy absorption capacity, 4/10 nanosecond high current impulse withstand, 2ms square wave current passing capacity and other indicators have reached the leading level in China. 2、 Zinc oxide arrester has excellent protection characteristics. Zinc oxide arrester is an electrical product used to protect various electrical equipment in the power system from over-voltage damage. It has good protection performance. Because the nonlinear volt ampere characteristics of zinc oxide valve slice are very good, only a few hundred microamps of current can pass through under normal working voltage, which is convenient to design into a gapless structure, making it have the characteristics of good protection performance, light weight and small size. When the overvoltage intrudes, the current flowing through the valve plate increases rapidly, while limiting the amplitude of the overvoltage, releasing the energy of the overvoltage, and then the zinc oxide valve plate returns to the high resistance state, making the power system work normally. 3、 The zinc oxide arrester has good sealing performance. The arrester element adopts high-quality composite jacket with good aging performance and air tightness. Measures such as controlling the compression amount of the seal ring and adding sealant are taken. The ceramic jacket is used as the sealing material to ensure reliable sealing and stable performance of the arrester. 4、 The mechanical performance of zinc oxide arrester mainly considers the following three factors: ⑴ Seismic force; ⑵ The higher wind pressure acting on the arrester ⑶ The top of the arrester bears the larger allowable tension of the conductor. 5、 Good decontamination performance of zinc oxide arrester The gapless zinc oxide arrester has high pollution resistance performance. At present, the specific creepage distance specified in the national standard is: ⑴ Grade II medium pollution area: creepage distance 20mm/kv ⑵ Grade III heavy pollution area: creepage distance 25mm/kv ⑶ Grade IV extra heavy pollution area: creepage distance 31mm/kv Ⅵ. The high operation reliability of zinc oxide arrester long-term operation reliability depends on the quality of the product and whether the selection of the product is reasonable. Its product quality is mainly affected by the following three aspects: the rationality of the overall structure of A arrester; B Volt ampere characteristics and aging resistance characteristics of zinc oxide valve piece C Sealing performance of lightning arrester. 7、 Power frequency withstand capability Due to various reasons in the power system, such as single-phase grounding, long line capacitance effect and load shedding, the power frequency voltage will rise or the transient overvoltage with high amplitude will occur. The arrester has the ability to withstand a certain power frequency voltage rise within a certain period of time. 1. The metal oxide arrester (MOA) shall be installed near the distribution transformer side in parallel with the distribution transformer during normal operation, with the upper end connected to the line and the lower end grounded. When the line has overvoltage, the distribution transformer at this time will bear three parts of voltage drop generated when the overvoltage passes through the arrester, lead and grounding device, which is called residual voltage. In these three overvoltage parts, the residual voltage on the arrester is related to its own performance, and its residual voltage value is certain. Residual voltage on the grounding device can be eliminated by connecting the grounding downlead to the distribution transformer housing and then to the grounding device. How to reduce the residual voltage on the lead becomes the key of protection distribution transformer. The impedance of the lead is related to the frequency of the current passing through. The higher the frequency, the stronger the inductance and the greater the impedance of the lead. It can be seen from U=IR that in order to reduce the residual voltage on the lead, the lead impedance must be reduced. The feasible way to reduce the lead impedance is to shorten the distance between the MOA and the distribution transformer to reduce the lead impedance and lead voltage drop. Therefore, the lightning arrester should be installed near the distribution transformer. 2. The low voltage side of the distribution transformer shall also be installed. If the low voltage side of the distribution transformer is not installed with MOA, when the lightning current is discharged from the arrester on the high voltage side to the ground, a voltage drop will be generated on the grounding device. The voltage drop will act on the neutral point of the winding on the low voltage side through the distribution transformer housing at the same time. Therefore, the lightning current flowing through the LV side winding will make the HV side winding induce a very high potential (up to 1000kV) according to the transformation ratio. This potential will be superimposed with the lightning voltage of the HV side winding, causing the neutral point potential of the HV side winding to rise and breakdown the insulation near the neutral point. If MOA is installed on the low-voltage side, when the discharge of the MOA on the high-voltage side increases the potential of the grounding device to a certain value, the MOA on the low-voltage side starts to discharge, reducing the potential difference between the outgoing end of the low-voltage side winding and the neutral point and the housing, so that the influence of the "reverse transformation" potential can be eliminated or reduced. 3. The MOA grounding wire should be connected to the distribution transformer housing. The MOA grounding wire should be directly connected to the distribution transformer housing, and then the housing should be connected to the ground. It is wrong to connect the grounding wire of the arrester directly to the ground, and then lead another grounding wire from the grounding pile to the transformer shell. In addition, the grounding wire of the arrester should be as short as possible to reduce the residual voltage. 4. The insulation resistance and leakage current of MOA shall be measured and tested regularly in strict accordance with the requirements of the regulations. Once the insulation resistance of MOA is found to be significantly reduced or broken down, it shall be replaced immediately to ensure the safe and healthy operation of the distribution transformer. During the daily operation and maintenance of the lightning arrester in this section, the pollution condition of the porcelain bushing surface of the lightning arrester should be checked, because when the porcelain bushing surface is seriously polluted, the voltage distribution will be very uneven. In an arrester with shunt shunt resistance, when the voltage distribution of one element increases, the current through its shunt resistance will increase significantly, which may burn out the shunt resistance and cause a fault. In addition, it may also affect the arc extinguishing performance of valve type arrester. Therefore, when the surface of arrester porcelain bushing is seriously polluted, it must be cleaned in time. Check the lead wire and grounding down lead of the arrester for burn marks and broken strands, and check whether the discharge recorder has passed the inspection, so it is easy to find the hidden defects of the arrester; Check whether the lead at the upper end of the arrester is well sealed. If the arrester is poorly sealed, water will enter and become damp, which may cause accidents. Therefore, check whether the cement joint at the connection between the porcelain sleeve and the flange is tight. Install a waterproof cover on the lead at the upper end of the 10 kV valve type arrester to prevent rainwater infiltration; Check whether the electrical distance between the lightning arrester and the protected electrical equipment meets the requirements. The lightning arrester should be as close to the protected electrical equipment as possible, and the action of the recorder should be checked after a thunderstorm; Check the leakage current. When the power frequency discharge voltage is greater than or less than the standard value, carry out maintenance and test; Overhaul the discharge recorder if it operates too many times; Cracks are found at the porcelain bushing and cement joint; If flange plate and rubber pad fall off, maintenance shall be carried out. The insulation resistance of lightning arrester shall be checked regularly. The 2500 V insulation megger shall be used for measurement, and the value obtained from the side shall be compared with the previous result. If there is no obvious change, it can continue to be put into operation. When the insulation resistance drops significantly, it is generally caused by damp due to poor sealing or spark gap short circuit. When it is lower than the acceptable value, the characteristic test shall be conducted; When the insulation resistance increases significantly, it is generally caused by internal parallel electricity, poor contact or fracture of resistance, spring relaxation and separation of internal components. In order to find the hidden defects inside the valve type arrester in time, a preventive test should be carried out before the thunderstorm season every year. [1]? Edit the common lightning arresters of well-known lightning protection brands in the market at present, including Haide Haide lightning arrester, Shenzhen Ansun lightning arrester, Nanyang Jinguan metal zinc oxide lightning arrester, LKX Lei Kexing lightning arrester, Dikai lightning arrester, KBTE Kobit lightning arrester in mainland China, TOP lightning arrester, Soule lightning arrester in France, ESPfurse lightning arrester in Britain, OBO lightning arrester in Germany, Jinli JLSP products, DEHN lightning arrester, PANMAX lightning arrester in the United States, INNOVATIVE lightning arrester, POLYPHASER antenna lightning arrester in the United States. SPD selection 1. Components used in lightning arrester Power supply Lightning energy absorption in lightning arrester, mainly zinc oxide varistor and gas discharge tube. The zinc oxide varistor is a voltage limiting protection device. When there is no pulse voltage, it presents a high resistance state. Once it responds to the pulse voltage, it immediately limits the voltage to a certain value, and its impedance suddenly changes to a low resistance state. Compared with the gas discharge tube, its greater advantage is that when it absorbs the pulse voltage, because the residual voltage is higher than the working voltage, it will not cause the instantaneous short circuit of the power supply, nor will it generate the freewheeling current. The response time of ZnO varistor is faster than that of gas discharge tube. The breakdown voltage of gas discharge tube is very sensitive to the rise rate of pulse voltage. The faster the voltage rise rate is, the higher the ignition voltage is, and the faster the response time is. The power supply arrester, which can correctly select the varistor and gas discharge tube and combine their respective advantages, has relatively good overall performance. The power supply arrester requires zinc oxide varistors with excellent energy withstand characteristics. The energy withstand characteristics are mainly described by three indicators: rated lightning impulse current, large lightning impulse current and energy tolerance. These characteristics are related to the surface area of zinc oxide varistors and the heat dissipation conditions of components. The energy tolerance of varistors of the same specification will vary greatly due to different manufacturing processes and raw material formulations of different manufacturers. The gas discharge tube has a strong ability to withstand large energy shocks. However, in specific use, because the residual voltage of the gas discharge tube is extremely low during discharge, which is similar to the short circuit state, it cannot be used alone in the power arrester. The current resistance of the gas discharge tube is related to the pipe diameter. The larger the pipe diameter, the better the current resistance. The quality problems of gas discharge tubes are mainly manifested as chronic gas leakage, reliability problems in long-term use (that is, the DC breakdown voltage value is shifted after multiple lightning strikes), and photosensitive effect and dispersion are large. Although the domestic gas discharge tubes have been greatly improved in recent years and their quality is gradually improving, the overall quality problems still exist, especially the reliability problems and chronic gas leakage problems. Therefore, the imported brand gas discharge tube shall be selected as the preferred product among the power supply arrester, and the diameter of the gas discharge tube shall be more than Ф 8 ㎜. The selection of capacitor and hot fuse in power arrester is also very important. The power supply arrester has been working in the power grid for a long time, and there are many cases of damage to the whole power supply arrester due to the quality problem of the capacitor. Therefore, the withstand voltage selection of the capacitor is very important, especially the ability to withstand the impact of high pulse voltage. In contrast, foreign products are better than domestic products, and the capacitor quality of Hitachi and OKAYA is superior. The function of the hot melt fuse in the power supply arrester is that when the lightning current exceeds the larger bearing capacity of the power supply arrester, the fuse can be disconnected due to the over-current effect, and the zinc oxide varistor temperature rise due to the over-current effect can also be disconnected, playing a dual role of over-current and temperature protection. Under normal working conditions, the current of the power supply arrester is very small, and it only plays a protective role under transient conditions in the event of lightning impulse or impulse voltage impulse, so it is different from the use conditions of conventional hot-melt fuses. Therefore, the hot-melt fuses in the power supply arrester should have unique performance, that is, fusing characteristics under transient conditions. 2. Advanced design scheme The design scheme of the arrester has good components, and the advanced design scheme is a necessary condition to ensure the quality of the power arrester. According to the analysis and comparison of domestic and foreign products, the following aspects should be fully considered when designing power arrester. The reasonable positioning of the lightning current impulse withstand level of the power supply arrester is the determination of the rated surge current value and the larger surge current value of the power supply arrester. At present, some power arrester manufacturers in the market, for the purpose of advertising, product competition and other commercial activities, arbitrarily improve the level of lightning current impact resistance, which is a very irresponsible attitude towards users. Lightning disaster has great destructiveness to modern electronic equipment. The magnitude of lightning current in a certain area is difficult to be determined by a single digital quantity due to many uncertain factors such as geographical environment, meteorological conditions and power supply wiring mode of electronic equipment. Therefore, the manufacturer should have a large margin for the design of power arrester. Generally, the design of surge current should be twice the larger surge current value of the power supply arrester, and the larger surge current value should be twice the rated surge current value of the power supply arrester. This design margin is responsible for the user. In the specific circuit designed by the manufacturer, the redundant circuit structure of multi-channel surge current absorption shall be adopted, that is, when a surge current absorption circuit is damaged due to a component, it will automatically exit the whole circuit of the power arrester, without affecting the normal operation of the whole power arrester. Because of the above design margin, even if one or even two absorption circuits exit the whole circuit, the lightning protection capability of the whole power arrester will not be affected. This redundancy design scheme will greatly improve the reliability of power arrester, and is the preferred protection equipment for lightning protection of power lines in multi lightning areas. 3. Reasonable and scientific production process in terms of production process and quality management system is the guarantee condition to ensure the quality of power arrester. In the production process of power arrester, the manufacturer should pay attention to the following aspects. Damp heat has always been an important reason for the failure of varistors, which shows that under the influence of long-term humid environment, the leakage current of varistors increases significantly, and the voltage of varistors decreases significantly. For the whole power supply arrester, due to the impact of humid environment, once the transient overvoltage or lightning current impact occurs in the power grid, it is likely to cause local short circuit and damage. Since thunderstorm season is often a humid and hot meteorological environment, the damp and heat prevention technology of power arrester is very important. The manufacturer usually adopts the production process of epoxy resin potting. Some manufacturers can perform vacuum pumping in the process of epoxy resin filling and sealing, so the effect is better. Therefore, when selecting the power arrester, in addition to watching the manufacturer's component selection, design scheme and production process, quality management is also very important. This includes the test system and safety system for component procurement, storage, inspection, assembly, aging, residual voltage and leakage current. To sum up, the selection of high quality power arrester should not only focus on the manufacturer's advertising, but also go to the manufacturer to see the above aspects, especially the selection of key components, design scheme and production process. In addition, local meteorological conditions, annual thunderstorm days and property losses caused by thunderstorms should also be comprehensively considered together with the protection level of power supply arrester. The principle of lightning arrester In view of the various lightning arresters that appear in the market today, the quality is uneven, and some of them are even unheard of (such as: lightning arresters that do not need grounding, until now, they have no understanding of their working principle). Therefore, by introducing the working principle and composition of lightning arresters, it is helpful for customers to identify the true and false, the advantages and disadvantages. In terms of response characteristics, lightning arrester elements can be divided into soft and hard ones. Discharge elements with hard response characteristics include spark gap (angle spark gap and coaxial spark gap based on arc chopping technology) and gas discharge tube, while discharge elements with soft response characteristics include metal oxide varistor and transient suppression diode. The difference between these components lies in their discharge capacity, response characteristics and residual voltage. Lightning arresters use their different advantages and disadvantages to develop their strengths and circumvent their weaknesses and combine them into various lightning arresters to protect circuits. 1、 Spark gap 1. Discharge gap: the principle is that two electrodes, such as ox horn, are separated by insulating materials in a short distance. When the electric field strength between the two electrodes reaches the breakdown strength, a current path is formed between the electrodes. When the lightning wave arrives, it first breaks down at the gap to ionize the air spark gap arrester of the gap, forming a short circuit. The lightning current flows into the earth through the gap, and the voltage at both ends of the time gap is very low, so as to protect the line. When the electric field strength is lower than the breakdown gap, the discharge gap arrester will return to the insulation state. It is often used for lightning protection of high-voltage lines. In low-voltage system, it is usually used for the front protection of power supply. The advantages and disadvantages of spark gap arrester products lie in the materials for making electrodes, gap distance and insulation materials. Advantages: It has strong discharge capacity and large flow capacity. The 10/350 μ s pulse waveform can dredge the 50KA pulse current. For the 8/20 μ s pulse current, it can be greater than 100KA. It has high insulation resistance, small parasitic capacitance and small leakage current. It will not bring any harmful effects to the normal working equipment. Disadvantages: high residual voltage (2.5~3.5KV), long reaction time (≤ 100ns), low action voltage accuracy, and power frequency freewheeling. Therefore, a fuse should be connected in series in the protection circuit to quickly cut off the power frequency freewheeling. Note: Since two discharge tubes are respectively installed on two wires of a circuit, sometimes they will discharge at different times, resulting in potential difference between the two wires. In order to make the discharge tubes on the two wires discharge at a uniform time and reduce the potential difference between the two wires, a three-stage discharge tube is developed. It can be regarded as the combination of two secondary discharge tubes. One stage in the middle of the three stage discharge tube is used as the common ground wire, and the other two stages are connected to two conductors of the circuit respectively. 2. Gas discharge tube (GDT): It is a ceramic or glass package, filled with inert gas (such as argon) of certain pressure, switch type protective element, with two electrode and three electrode structures. When the electric field strength reaches the strength of breakdown inert gas, it will cause gap discharge, thus limiting the voltage between electrodes. 8/20 μ s pulse current can dredge 10KA. The discharge voltage is unstable. When the voltage is greater than 12V and the current voltage is 100mA, the subsequent current will be generated. It is usually used in measuring, controlling and regulating technical circuits and electronic data processing transmission circuits. 2、 Metal oxide varistor (MOV) is a metal oxide semiconductor nonlinear resistor with zinc oxide as the main component. When the voltage applied to both ends of the resistor is less than the voltage sensitive voltage, the varistor is in a high resistance state. If it is connected in parallel to the circuit, the valve is in a broken state; When the voltage applied to both ends of the varistor is greater than the voltage, the varistor will breakdown, showing a low resistance value, or even close to the short-circuit state. The breakdown state of the varistor can be recovered. When the voltage higher than the varistor voltage is removed, it will return to the high resistance state. When the power line is struck by lightning, the high voltage of the lightning wave makes the varistor breakdown, and the lightning current flows into the earth through the varistor, so that the similar voltage on the power line is clamped in a safe range. Zinc oxide varistor surge arresters are now in circulation in the market. They were produced in large quantities in China in the late 1980s. They are considered to be relatively new and technologically advanced, and will be introduced in detail. At present, zinc oxide lightning arresters are used for power transmission lines in China. Advantages: wide switching voltage range: 6V~1.5KV, fast reaction speed (25ns), low residual voltage (can reach the safe working voltage of terminal equipment), large flow (2KA/cm2), no continuous current, and long service life. Disadvantages: It is easy to age. After several actions, the leakage current will increase, which will cause the varistor to overheat and eventually lead to large aging capacitance. In many cases, it is not used in high-frequency and ultra-high frequency systems. The capacitance and the conductor capacitance form a low pass. This low pass will cause severe attenuation of the signal. However, when the frequency is lower than 30KHZ, the attenuation can be ignored. 3、 Transient voltage suppressor (TVS) 1. Bipolar discharge tube: there are two forms: one is Zener type (unidirectional avalanche breakdown), and the other is bidirectional silicon varistor. Its performance is similar to that of switching diode. Under the action of the specified reverse voltage, when the voltage at both ends is greater than the threshold voltage, its working impedance can be immediately reduced to a very low level to allow large current to pass through, and the voltage at both ends is clamped at a very low level, thus effectively protecting the precision components in the end electronic products from damage. Bidirectional TVS can absorb instantaneous large pulsating power in both positive and negative directions, and clamp the voltage at a predetermined level. Suitable for AC circuits. Advantages: extremely fast action time, reaching picosecond level. Low limit voltage, low breakdown voltage, used in various electronic fields. Disadvantages: The current load is small, and the capacitance is quite high, generally below 20pF. The current ceramic discharge tube can achieve 3-5 pF. The surge protection system required by the electronic information system is generally composed of two or three levels. The gas discharge tube, varistor and suppression diode are used, and the characteristics of various surge suppressors are used to realize reliable protection. The gas discharge tube is generally placed at the input end of the line as a primary surge protection device, which bears large surge current and belongs to the discharge type device. The secondary protection device adopts a varistor, which can limit the surge voltage to a lower level in a very short time (ns). For highly sensitive electronic circuits, suppression diodes can be used as three-level protection. Limit the surge voltage within the insulation level of the terminal electronic equipment in a shorter time. As shown in the figure, when lightning and other surges arrive, the suppression diode will be turned on first to accurately control the instantaneous overvoltage at a certain level. If the surge current is large, the varistor will start and discharge a certain amount of surge current. At this time, the voltage at both ends of the varistor will rise until the front gas discharge tube is pushed to discharge, releasing the large current to the ground. When the three devices are far away from each other in the circuit, the conduction sequence will start from the gas discharge tube and turn on in turn. The work of the arrester starts from the end of the equipment with fast reaction time, and then starts from the front end step by step. Simply using gas discharge tube to protect the equipment at the rear end will cause the following problems: too long conduction time, too large residual voltage, which may exceed the withstand voltage level of the equipment at the rear end. After discharge, power frequency freewheeling will be generated. To avoid the above problems, another circuit is used (Figure 3). In order to solve the problem of generating power frequency freewheeling, and also to prevent the thermistor from heating, self explosion or aging due to excessive leakage current, we connect a varistor in series on the gas discharge tube, so as to avoid generating power frequency freewheeling and prevent the varistor from self explosion and aging due to leakage current. But a new problem arises again, so the action time of the arrester is the sum of the conduction time of the gas discharge tube and the conduction time of the varistor. Assuming that the conduction time of the gas discharge tube is 100ns and the conduction time of the varistor is 25ns, their total reaction time is 125ns. In order to reduce the reaction time, a varistor is incorporated into the circuit, so that the total reaction time is 25ns. When overvoltage occurs, the suppression diode acts first as a fast acting element. The circuit design is that before the suppression diode may be destroyed, the discharge current will be converted to the front discharge path with the increase of amplitude, that is, the gas filled discharge circuit. Us △ u ≥ UgUs: voltage on the suppression diode △ u: voltage on the decoupling induction coil Ug: action voltage of the gas discharge tube If the discharge current is less than this value, the gas discharge tube will not act. This circuit can not only take advantage of the quick action of the arrester under the condition of low protection level, but also achieve high discharge capacitance. In this way, the disadvantage that the primary fuse for restraining diode overload frequently cuts off the circuit in case of power supply freewheeling can be eliminated. High frequency lines can also use ohmic resistors as decoupling elements, which can be used together with low capacitance bridge lines. 2. Three pole discharge tube: two two pole discharge tubes are installed on two wires, which will lead to potential difference. Therefore, there is a three pole discharge tube. One pole is added for public grounding, which can reduce the time difference (0.15~0.2 μ s) and the resulting transverse lightning voltage amplitude. On the market, the common power arrester devices generally use varistors for primary, secondary and tertiary power supplies. When the distance of this combination mode is more than 5 meters, the conduction time starts from the front stage to the rear stage. If the front stage uses gas discharge tubes and the second and third stages use varistors, the distance between the front stage and the second stage must be more than 10 meters, and the distance between the second stage and the third stage must be more than 5 meters, so that the first stage can act first. Otherwise, the front stage may not act, and the secondary and tertiary lightning arresters do not have such large flow capacity, resulting in the failure of the arrester to effectively protect the equipment. This must be noticed in engineering design. More pictures of zinc oxide arrester (2 pieces)
