1, arrester dimensions Surge arresters are made according to indoor and outdoor dual-use conditions to determine the strength of its porcelain sets, its dimensions and the valve material. When used for overhead lines or outdoor power distribution equipment, because of their large spacing, arrester dimensions will not have a negative impact. Indoor handcart type switchgear because of its small size, large size arrester will bring adverse effects. Silicon carbide arrester SiC valve unit flow capacity of only one-fourth of the ZnO valve, under the same flow capacity (5kA) conditions, SiC valve larger diameter, arrester diameter is also large; at the same rated voltage And residual voltage conditions, silicon carbide surge arrester height greater than the zinc oxide. Especially in the 35kV grade more significant. Such as JYN1-35 type handcart 112 program, the original FYZ1-35 type gapless zinc oxide surge arrester, high only 650mm, installed in the cabinet at the rear of the room simple handcart, the upper isolation plug, because the product has been discontinued , Engineering design adhere to the use of FZ3-35 silicon carbide surge arresters, high 1500mm, compartment height is not enough, only the bus compartment and the compartment partition removed, the arrester directly connected with the main bus, so arrester test or replacement must be in the whole Section of the main bus power off, operation and maintenance difficulties, and surge arresters larger diameter, air space between the phase is not enough, the installation of insulation between the phase separator, insulation aging moisture damage potential problems. Zinc oxide arrester diameter and height is relatively small, 35kV-class can also be made as hanging, such as Y5CZz-42 / 110L series gap zinc oxide surge arrester, the height of only 640mm. Miniaturization arrester is more conducive to handcart installation and use. 2, arrester performance and cost-effective Zinc oxide arrester without gaps in the long-term operation of the grid voltage to withstand the harsh working conditions, the manufacture of the valve to the valve when the test rigorous screening, high cost low, so the price is high; because of its transient over-voltage withstand capacity Poor fatal weakness, not suitable for the promotion of the use of 3 ~ 35kV power grid in our country. Zinc oxide surge arresters in series with gaps greatly improve the long-term working conditions of the valve plate, the product testing requirements of the valve plate testing relatively low, the high pass rate low cost, the price is cheaper, zinc oxide arrester series gap clearance than the gap Zinc oxide arresters are generally cheaper and sometimes cheaper than silicon carbide arresters (such as 3 ~ 10kV FZ type) cheaper, while it has other anti-lightning devices have advantages and disadvantages to avoid weaknesses, in fact, the most advanced lightning protection appliances, with high performance and low cost , Is the popularization and popularization product of lightning arrester replacement. 3, arrester life problems The service life of arrester is related to many factors. Except manufacturing quality, damp sealing and other external factors, the aging rate of arrester valve is the key factor affecting life expectancy. Silicon carbide arrester due to its action and heavy load, large freewheeling, poor stability of the operating characteristics may suffer from transient over-voltage hazards and other reasons, accelerate the aging valve, the life is not long, usually 7 to 10 years, even with only 3 ~ 5 years. Zinc oxide arrester gapless grid voltage long-term grid, the harsh working conditions, inflection point voltage is low, the frequency of action, but also may suffer from transient over-voltage hazards, thermal damage and other reasons, quickly accelerate the aging valve, short life expectancy , Some shorter than silicon carbide arrester. The gap between series gap zinc oxide surge arresters ensures that the valve plate withstands high voltages for very short periods of time (within 100μs) during overvoltage protection and in other cases for grid voltage or isolated (pure gap) Or in a low potential state (composite gap resistance partial pressure), greatly improve the long-term working conditions of the valve, but also from transient over-voltage hazards and thermal damage to ensure that the valve temperature does not exceed 55 ℃, thus ensuring the arrester life of 20 Years or more.