METHOD FOR LOWERING EARTHING RESISTANCE OF POWER TRANSMISSION STEEL TOWER LEG

摘要

PURPOSE:To lower the rise of electric potential due to a steel tower earthing resistor at the time of lightning by altering the resistance of a buried conductor according to the measured earthing resistance of each tower leg of an power transmission steel tower. CONSTITUTION:Earthing resistance Ra, Rb, Rc, Rd of four tower legs 1a, 1b, 1c, 1d of a power transmission steel tower are either measured by measuring for each of the legs 1a-1b by an earthing resistance measuring apparatus or calculated by measuring practical divided current of lightning current for each of the legs 1a-1d. Then, according to each measured resistance, each length La, Lb, Lc, Ld for each of buried linear conductors 2a, 2b, 2c, 2d which are connected with the legs 1a-1d each and buried in ground horizontally is so determined as to make the earthing resistance Ra-Rd of each tower leg 1a-1d become almost equal and the compound resistance of the earthing resistance Ra-Rd of each tower leg 1a-1d be within a standard compound resistance of four legs. As a result, the earthing resistance of each of the tower legs is made almost equal each other and the rise of electric potential due to the leg earthing resistors at the time of lightning is lowered and accidents by lightning is prevented.