CAVITY-TYPE DISCHARGE ARRESTER FOR LIGHTNING OVERVOLTAGE PROTECTION OF ELECTRICAL EQUIPMENT, AND INSULATOR AND ELECTRICAL POWER TRANSMISSION LINE EQUIPPED WITH SUCH DISCHARGE ARRESTER

摘要

The invention relates to discharge arresters for lightning overvoltage protection of electrical equipment. The arrester (100) according to the invention comprises an insulating body (1) made of a dielectric, two main electrodes (2, 3) mechanically connected to the insulating body (1), and at least two intermediate electrodes (4) mechanically connected to the insulating body (1) and disposed between the main electrodes (2, 3) in such a way that an electric discharge can develop between adjacent main and intermediate electrodes as well as between adjacent intermediate electrodes; the intermediate electrodes (4) are disposed inside the insulating body and separated from its surface by a dielectric layer; discharge chambers (6) opened to the surface of the insulating body (1) are made between the intermediate electrodes (2, 3, 4). The discharge arrester (100) is characterized by that it has inside air cavities (7) communicating with discharge chambers (6), the total volume of cavities communicating with one discharge chamber is lying within in the range V=(0.1-10)g³, where g is length of the spark gap (5) between adjacent electrodes of the chamber. The discharge arrester ensures extinguishing of impulse lightning overvoltage arc without a mains follow current, which makes it possible to use it in mains with high short-circuit currents. Further, the invention relates to an insulator and to an electric transmission line equipped with said discharge arrester.