Strength Assessment of Deteriorated OHL Conductors and Earth Wires Based on Non-Destructive Testing

Abstract

Safety operation of overhead lines depends on many factors including strength of conductors and earth wires. Therefore worn-out or defective conductors or earth wires must be detected. Estimation of conductor technical conditions is based on comparison of revealed flaws with requirements of overhead line project and build documentation. It is well known that conductors are affected by corrosion, friction and fatigue wear. All this factors may cause loss of strength and even breakage of conductor. Steel core is the most important part of conductor when it comes to mechanical loads. That is why it is very important to know actual technical conditions of steel core of conductor. Worn or defective wires must be repaired or replaced. Principles of strength assessment of deteriorated of steel-aluminum conductors and steel earth wires based on magnetic non-destructive testing technique are presented. The retention of overhead line conductor and earth wire is one of the most reasonable ways to eliminate the unacceptable clearances. The allowable magnifying tension, regarding the reliable operation, is set relying upon the non-destructive testing of conductors or earth wires in actual state. The measured loss of metallic cross-section area due to abrasion, corrosion etc. and local wire breaks are treated as input data for mechanical model of objects under test. The residual strength estimates give the specialists network company further information that helps to make a valid decision on testing time-limit and policy. Some results of assessing the strength of overhead line conductors and earth wires according to the NDT data are demonstrated.