EHV transmission system consisting of long span transmission lines and towers is an integrity as a structure,in the process of design,the strength calculation of the conductor and the tower is independent,it is difficult to compute the longitudinal unbalanced tension of the tower.

These differences will be favorable to reduce the longitudinal unbalanced tension and weight of the suspension towers and poles,while the too small longitudinal unbalanced tension will weaken the longitudinal stiffness of the towers and poles,which is unfavorable to the cascade of towers.

Take an example for 220 kV Tiandang line,The paper makes researches on icing overburden ability and sag and unbalanced tension caused by icing of conductor and ground wire,analyzes the reasons of tower collapses and line breakage,and give suggestions of rebuilding measures to improve icing-resistance ability of 220 kV transmission Line in Guangxi according to the analysis results.

Analysis and calculation of transmission line unbalanced tensile force;

This paper introduces multirope friction winder appear steel wire rope strain imbalance phenomena in using,and harm to strain imbalance of steel wire rope,and analysis produce reason of strain imbalance,accordingly pertinence put forward eliminate strain imbalance of multirope friction winder steel wire rope method.

Presentated the domestic and oversea primary tensility balance methods of multirope friction hoisting machinery at present,analyzed and compared the advantage and disadvantage of each balance methods,suggesting that should choose appropriate balance method according to different conditions so as to insure the safe of hoisting.