Operation and maintenance of lightning arrester manufacturers
(1) Lightning arrester application:
The power transmission, transformation and distribution equipment of the power system will be affected by the following voltages during operation:
① Long-term working voltage;
②Transient overvoltage due to ground fault, resonance and other reasons;
③Lightning overvoltage;
④ Operation overvoltage.
Lightning overvoltage and operating overvoltage may have higher values. Simply relying on improving the insulation level of equipment to withstand these two overvoltages is not only economically unreasonable, but also often technically impossible. A positive approach is to use electrical appliances that specifically limit overvoltage to limit the overvoltage to a reasonable level, and then select equipment with corresponding insulation levels accordingly. Lightning arrester is one of the most important electrical appliances that limits overvoltage. The protective characteristics of the arrester are the basis for the insulation coordination of the protected equipment. Improving the protective characteristics of the arrester can improve the safety and reliability of the operation of the protected equipment, and can also reduce the insulation level of the equipment, thereby reducing the cost. The higher the voltage level of the equipment, the more significant the economic benefits brought by reducing the insulation level.
The arrester is installed on the protected equipment, and the overvoltage is transmitted from the line to the arrester manufacturer. When its value reaches the arrester operating voltage, the arrester operates to limit the overvoltage to a certain level (called the protection level). After the overvoltage, the arrester immediately returns to the cut-off state and the power system returns to normal state.
Lightning arresters should meet the following basic requirements:
① It can withstand the continuous operating voltage of the system for a long time, and can withstand the transient overvoltage that may occur in the short term;
② Under the action of overvoltage, its protection level meets the requirements of insulation level;
③Can withstand the energy generated by discharge current under the action of overvoltage;
④Can quickly return to normal working condition after overvoltage.
(2) Normal operating conditions of arrester:
The normal operating conditions of the arrester are:
① Suitable for indoor and outdoor operation;
②Ambient temperature is +40℃～-40℃;
③Can withstand sunlight radiation;
④The altitude does not exceed its design height;
⑤The frequency of the power supply is not less than 48Hz and not more than 62Hz;
⑥The power frequency voltage applied to the arrester for a long time does not exceed the allowable value of the continuous operating voltage of the arrester;
⑦ Areas with earthquake intensity of 7 degrees and below;
(3) Lightning arrester classification:
Our country's general-purpose surge arrester series and its application range are as follows:
Universal surge arrester series and its application range
Serial number Name Series code Application scope
1 Low-voltage valve-type surge arrester FS is used in low-voltage networks to protect AC appliances, energy meters and low-voltage windings of distribution transformers
2 Ordinary valve-type arresters for power distribution are used in 3-10kV AC power distribution systems to protect transformers and other electrical equipment
3 Ordinary valve arrester for power stations FZ is used in 3~110kV AC system to protect electrical equipment such as transformers
4 电站用磁吹阀式避雷器 FCZ 用于35kV及以上交流系统，保护变压器等电气设备，尤其适合于绝缘水平较低或需要限制操作过电压的场合
5 Magnetic blow valve arrester for protecting rotating electrical machines FCD is used to protect alternators and electric motors
6 无间隙金属氧化物避雷器 YW 包括序号1到序号5中的全部应用范围
7 Metal oxide arrester with series gap YC is used in 3~10kV AC system to protect distribution transformers, cable heads and other electrical equipment. Compared with YW, each has its own characteristics
8 有并联间隙氧化物避雷器 YB 用于保护旋转电机和要求保护性能特别好的场合
9 DC metal oxide arrester YL is used to protect DC electrical equipment
2. Arrester installation, operation and maintenance
(1) Lightning arrester installation:
①Inspection before installation:
1) Whether the rated voltage of the arrester is the same as the line voltage;
2) Check whether there are cracks on the porcelain plate of the chassis, and whether there are cracks, damage, flashover marks and glaze loss on the surface of the porcelain parts. If there is any damage, the damaged area should be less than 0.5cm2, and it can continue to be used if it is damaged in no more than three places;
3) Gently shake the arrester in different directions. There should be no loose sound inside;
4) Check whether the gluing and sealing of the connection between the porcelain sleeve and the flange are in good condition.
②Electrical test:
1) Insulation resistance, use a 2500V megohmmeter to measure the insulation resistance, and compare it with the test value of similar lightning arresters. There should be no significant change in the insulation resistance value;
2) Power frequency breakdown voltage test, FS type arrester power frequency discharge voltage standards: rated voltage is 3kV, 6kV, 10kV; newly installed and overhauled arresters are 9~11kV, 16~19kV, 27~30kV; operating arresters are 8~12kV, 15~21kV, 23~33kV;
3) FZ type arresters generally do not need to undergo power frequency discharge tests, but arrester leakage current measurements are required.
③Installation requirements:
1) The arrester should be installed vertically, and the inclination should not be greater than 15°. The installation location should be as close as possible to the protection equipment. The electrical distance between the arrester and the 3-10kV equipment is generally no more than 15m. If the live part that is easy to inspect and patrol is less than 3m from the ground, a barrier should be installed;
2) The cross-sectional area of the joints between the arrester's leads, busbars, and conductors shall not be less than the specified value: the cross-sectional area of 3-10kV copper leads shall not be less than 16mm2, and the cross-section of aluminum leads shall not be less than 25mm2. For 35kV and above, the design requirements shall apply. It is also required that the upper and lower leads are firmly connected and must not be loose, and the oxide film and paint on each metal contact surface should be removed;
3) There should be enough space around the arrester. The distance between the live part and adjacent wires or metal structures should not be less than 0.35m, and the distance between the bottom plate and the ground should not be less than 2.5m, so as to prevent surrounding objects from interfering with the potential distribution of the arrester and reducing the gap discharge voltage;
4) The pull-wire insulator string of the high-voltage arrester must be firm, and its spring should be adjusted appropriately to ensure free expansion and contraction. The nut in the spring box must not be loose, and there should be a protective device; the tension of each tensioned insulator string in the same phase should be uniform;
5) The voltage equalizing ring should be installed horizontally and not skewed, and the three-phase center holes should be consistent; all loops (from busbars, lines to grounding leads) should not be circuitous and should be as short and straight as possible;
6) For arresters of 35kV and above, a discharge recorder should be installed on the ground loop, and the discharge recorder should be well sealed and installed in the same position as the arrester to facilitate observation;
7) Arresters composed of non-interchangeable multi-section basic components should be stacked in strict accordance with the factory serial numbers and order to avoid confusion of components of different arresters and reversal of the positions of components of the same arrester;
8) The arrester base should be well insulated from the ground, and the ground down conductor should be reliably connected to the metal shell of the protected equipment and connected to the main grounding device.
(2) Arrester operation:
The lightning arrester should be inspected and inspected at the same time as the power distribution device during operation. After lightning activity, special inspections should be added. The inspection items are as follows:
① Whether the porcelain sleeve is complete;
② Check whether the wires and grounding leads have burn marks or broken strands;
③ Whether the cement joints and paint are intact;
④ Check whether the upper cap lead of the 10kV arrester is tightly sealed and whether there is water intrusion;
⑤ Whether the surface of the porcelain sleeve is seriously contaminated;
⑥ Check whether the indication number of the action recorder changes, determine whether the arrester operates and make a record.
(3) Operation management of arrester:
① The time when the arrester is put into operation should be determined according to the local lightning activity. It is generally put into operation from early March to October every year;
② Before the arrester is put into operation every year, inspection and testing should be carried out. The test items are:
1) Use a 1000 to 2500V megohmmeter to measure the insulation resistance. Compared with the previous test value or the test value of the same model of arrester, the insulation resistance value should not change significantly;
2) Measure the power frequency discharge voltage. For the FS type arrester, when the rated voltage is 3kV, 6kV, and 10kV, the power frequency discharge voltage is 8~12kV, 15~21kV, and 23~33kV respectively;
3) FZ type arresters generally do not undergo power frequency discharge tests, but the leakage current of the arrester should be measured.
(4) Common faults during arrester operation:
①The arrester is damp inside. The phenomenon of moisture inside the arrester is that the insulation resistance is lower than 2500MΩ and the power frequency discharge voltage drops. Internal moisture may be caused by:
1) The fastening nut at the top is loose, causing water leakage or the washer of the bolt used to seal the top of the porcelain sleeve is not welded tightly. After the sealing washer ages and cracks, moisture and moisture seep into the inner cavity along the screw seams;
2) The small hole in the bottom sealing test is not welded firmly or blocked;
3) The porcelain sleeve is cracked, has blisters, and has cracks in the skirt gluing, etc. It is easy for moisture and moisture to enter;
4) After being used for a long time, the rubber gasket ages, becomes brittle and cracks, and loses its sealing effect;
5) The fan-shaped iron sheet used for pressing the bottom is not tightly plugged, causing the bottom plate to become loose, and the bottom sealing rubber gasket is not in the correct position, causing gaps to allow moisture to seep in;
6) The joint between the porcelain sleeve and the flange is uneven or the porcelain sleeve has cracks.
②The arrester explodes during operation:
It is common for explosions to occur during the operation of lightning arresters. The cause of the explosion may be caused by the system or the arrester itself:
1) Due to the occurrence of single-phase grounding in an ungrounded neutral point system, the non-faulty phase-to-ground voltage rises to the line voltage. Even if the voltage endured by the arrester is less than its power frequency discharge voltage, an explosion may occur under the action of a long-lasting overvoltage;
2) Due to ferromagnetic resonance overvoltage in the power system, the arrester is discharged, thereby burning out its internal components and causing an explosion;
3) When the line is struck by lightning, the arrester operates normally. Due to the poor arc-extinguishing performance of the spark gap itself, when the gap cannot withstand the recovery voltage and breaks down, the arc will re-ignite, and the power-frequency freewheeling will reappear, and the re-ignition valve will burn out the resistance, causing the arrester to explode; or due to the unqualified resistance of the arrester valve, although the residual voltage is reduced, the aftercurrent is increased, and the gap cannot extinguish the arc, causing an explosion;
4) An explosion may occur due to looseness or cracks at the joint between the lightning arrester sealing gasket and the cement, resulting in poor sealing.
Yichang Hengyuan Technology Co., Ltd. specializes in the production of European-style cable joints, plug-and-pull heads, cable branch boxes, American-style elbow joints, high-voltage vacuum circuit breakers, high-voltage load switches, arresters, zinc oxide arresters, tank arresters, over-voltage protectors, counters, monitors, heat-shrinkable cable accessories, Manufacturer of cold shrink cable accessories, T-heads, wall bushings, European cable accessories, American cable joints, transformer neutral point protection devices, fuses, isolating switches, PT cable heads, elbow cable joints, 10kV outdoor terminals, switch cabinets, cable intermediate joints, cable accessories and other products
