Ensuring the Structural Safety of Overhead Transmission Lines by Design

AbstractDuring service, transmission lines (TLs) will be subjected to unbalanced longitudinal loads due to events such as conductor breakage, insulator failure, and sudden ice shedding, which may damage TLs and subsequently hinder reliable power supply. Although unbalanced longitudinal loads are considered in current design codes, damage to TLs still occasionally occurs. This paper reviews the literature from the last 20 years pertaining to the response of TLs induced by the abovementioned events and associated tower failures. It comprises four main sections in relation to the sources of large unbalanced accidental loads: conductor breakage, sudden ice shedding, insulator breakage, and tower failure. Structural analysis methods to investigate these accidents are reviewed, and the latest research progress on modeling tower failure is discussed. Chinese code, American code and International Electrotechnical Commission code are compared to analyze the differences in accounting for longitudinal loads in these codes. In the end, several recommendations are provided for future design and research to ensure the structural safety of TLs.