The Influence of Tower Foundation Settlement on the Sag and Stress of Overhead Lines

The foundation settlement of transmission tower in mining area influences the sag and stress greatly and threatens the safety of transmission lines. This paper gives a new method for the calculation of stress and sag of overhead line based on catenaries state equations and the balance forces on suspension insulator under the condition of tower foundation settlement. Furthermore an example is analyzed by this new and precise method. The results show that the uniform settlement of tower has slightly influences on sag and stress of overhead transmission line, but the incline of tower foundations lead to dramatic change of sag and stress and will result in unbalance force on suspension insulators. So it is necessary to strengthen the online monitor of tower incline to ensure the safety of transmission lines in mining areas.