午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

Through the investigation and research about the electromechanical equipments in the Xinghe highway tunnel frequently struck by lightning in the Taihang Mountain Area, considering the geographical and meteorological environment of Xinghe and the insitu test, the measures to protect against direct lightning flashes and lightning electromagnetic impulses are discussed from the following five aspects: (1) protection of structures and power facilities against direct lightning flashes, (2) protection of highvoltage lines against overvoltage caused by lightning, (3) protection of lowvoltage electrical installations and electronic installations against overvoltage, (4) shielding, (5) equipotential bonding. The practice of several years proved that these measures are applicable.