Zinc oxide arresters have a long service life and have diverse advantages. Therefore, it has been used in power systems and distribution networks. Metal oxide arresters are mainly used to protect electrical appliances from lightning strikes and maintain working conditions without overvoltage. It is one of the most practical and reliable lightning arresters.
The principle of ZnO arrester is that the internal varistor can recover itself when it is impacted, and return to the high resistance state after the external voltage disappears. The protective function of the current is to flow into the earth through the varistor after a lightning strike. This process ensures that the zinc oxide arrester can control unsafe voltage to a certain value.
Metal oxide arresters each have their own characteristics. In order to test whether it can maintain the same performance and system stability in continuous applications, it can be tested at a certain quality and technology. The purpose of the test is to further understand the internal conditions of the zinc oxide arrester and check whether it can withstand the operating current.
The purpose of our test is to test whether the interior is waterproof and whether it will get wet. The object of the test is the internal valve of the zinc oxide arrester, which requires professionals to work on the valve plate. For example, check whether the saturation point of the V-V characteristic curve of the valve strip is normal through the values of DC voltage and current. In this way, the protective functions and electrical characteristics of the valve strip remain consistent with the factory performance and characteristics. Then you can check whether the zinc oxide arrester will appear after long-term operation, check whether its operating current is normal and whether it meets national standards.
The preparation work is to check whether the zinc oxide arrester is in normal working condition, whether the shell is cracked or damaged, and whether the zinc oxide arrester is not firm, shaking or making noise. If anomalies are discovered, maintenance and testing cannot be performed. If there is no abnormality in the zinc oxide arrester detection, you can enter the zinc oxide arrester detection process!
The environment of the test site we set up should be such that the zinc oxide arrester is placed in a suitable location before the thunderstorm season arrives. High-voltage arrester preparation testers include vibration meters above 2500V, megohmmeters above 2500V and high-voltage DC generators.
First, use a megohmmeter to test whether the high-voltage arrester is short-circuited. At the same time, the zinc oxide arrester can be connected to a megohmmeter to check the insulation resistance of the zinc oxide arrester and record the data within one minute. Generally speaking, the insulation resistance of zinc oxide arresters above 35kV will be greater than 2500mΩ, and the insulation resistance of zinc oxide arresters below 35kV will be greater than 1000MΩ. After this test, remember to conduct two stages of discharge work on the arrester.
Finally, the high-voltage arrester can withstand the test of operating current. Of course, the TCM test is to use a zinc oxide arrester under normal conditions, and then use a high-voltage DC generator to boost the voltage connected to the wiring: increase the current to 1mA, then read the value record of the voltage U1mA and then reduce the voltage to zero. The testing process is dangerous and requires professionals. When the current changes too much, the boost speed must be reduced. After reading the voltage value, calculate the value of 0.75 times U1mA, then continue testing and record the leakage current value after increasing the voltage to 0.75 times U1mA, and then reducing the voltage to zero. After completing this step, the test tool can be turned off, the wiring removed, and the zinc oxide arrester discharged.
As we all know, the service life of ZnO arresters at the same temperature is inversely proportional to the leakage current value. Therefore, if the leakage current value in the experiment is too large, it indicates that there are certain problems with the quality of the zinc oxide arrester. If the DC 1mA voltage value in the test deviates too much from the value in GB11032, the leakage current at 0.75u1ma will be greater than 50μA. The deviation between the actual measured value of U1mA and the initial value and the specified value indicates that there is a problem with the zinc oxide arrester's internal or factory settings. At this time, it is necessary to replace the zinc oxide arrester or perform arrester maintenance.
Yichang Hengyuan Technology Co., Ltd. is a professional manufacturer ofEuropean cable connector, plug-in head, cable branch box, American elbow type head, high-voltage vacuum circuit breaker, high-voltage load switch, lightning arrester, zinc oxide arrester, tank arrester, over-voltage protector,counter, monitors, heat shrink cable accessories, 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.
