Factors affecting the quality of zinc oxide arrester manufacturers and selection of parameters
The stability of gap discharge voltage is the standard for the protection performance of zinc oxide arresters. There are differences in the gap discharge characteristics between rod-rod pure air gap and ring-ring high-voltage insulator support. The former is an extremely uneven electric field, while the latter is a slightly uneven electric field; the former has a slightly lower discharge voltage and less dispersion, while the latter is not only highly dispersive, but also significantly affected by the pollution performance of high-voltage insulators. When pollution causes leakage current and reaches a certain value, it forms a "voltage divider" with the leakage current of the zinc oxide arrester body, which significantly changes the potential distribution of the entire zinc oxide arrester and increases the discharge voltage value of the zinc oxide arrester. This is something that designers must give full consideration to.
Tests by line zinc oxide arrester manufacturers
Different from the porcelain jacketed zinc oxide arrester, the jacket of the composite jacketed zinc oxide arrester is made of organic polymer materials. It must undergo many tests to verify its characteristics, such as weather resistance test, electric corrosion resistance test, salt spray resistance test, etc. Most of the requirements and test methods for these tests have been reflected in the latest version of IEC standards.
Composite Jacket Tracking and Electrical Corrosion Test
Zinc oxide arrester proportional components were made to scale. The temperature of the spray chamber is 20~25℃, the NaCl content in the salt spray is 9.8kg/m3, and it is sprayed to the proportional element at a speed of 3.9L/m3·h. At the same time, the equal-proportional continuous operating voltage Uc is applied to the proportional element for a duration of 1000h. During the test, there was no overcurrent interruption, the composite jacket of the proportional element had no marks, cracks or dendritic cracks, and the shed skirt did not break down.
Thermal engine test and boiling water boiling test
This test is used to verify the performance of the adhesive between the flange and the epoxy fiberglass cloth tube of the zinc oxide arrester under the combined action of hot, cold and mechanical forces. The test is conducted in two steps:
The proportional element is tested under the following conditions simultaneously: ① 2 hot and cold cycles of (-35±5) ℃ ~ (50±5) ℃, the high and low temperatures are maintained for at least 8 hours, and each cycle lasts for 24 hours; ② A load force of 50% of the rated tensile load is applied to the proportional element.
After the proportional element is boiled in a 0.1% NaCl solution for 42 hours, it is immediately soaked in an aqueous solution at ambient temperature for 24 hours. After taking it out, it is left in the air at ambient temperature for 24 hours until the surface is dry.
Selection of specific creepage distance, cold shrink cable terminal
The contamination resistance of the silicone rubber composite jacket is 66% higher than that of the porcelain jacket. This is determined by the hydrophobicity of silicone rubber, which comes from the methyl groups in the silicone rubber molecules that naturally repel water molecules. The test results show that the pollution resistance of the composite jacket is much higher than that of the porcelain jacket, but no quantitative conclusion has been reached yet.
The improved stain resistance of the composite jacket can be left to the user and power department as a margin consideration. Therefore, the design of specific creepage distance is still considered according to the standards of porcelain jacket. This design is also affected by two external factors: ① The composite jacket is easier to increase the specific creepage distance than the porcelain jacket, but the minimum distance of the arc must be guaranteed (such as ≥1m at 110kV); ② It is believed that the creepage distance of the two types of zinc oxide arresters with series gaps should be different: the creepage distance of the zinc oxide arrester body with gaps is ≥1.7cm/kV, which is considered safe, because the zinc oxide arrester body hardly withstands any voltage value under normal operating voltage; the insulation support For zinc oxide arresters with gaps, the creepage distance should be the sum of the creepage distance of the zinc oxide arrester body and the creepage distance of the supporting high-voltage insulator. The author recommends that the specific creepage distance should be specified separately, the zinc oxide arrester body ≥ 1.7cm/kV, the support High-voltage insulators ≥1.7cm/kV, because under different conditions of normal operation and lightning strike, both need to withstand almost 100% overvoltage respectively, and the overall creepage distance of zinc oxide arresters is ≥3.4cm/kV.
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
