Effect of Overhead Line Broken Strand Fault on Axial Temperature Decay Distance Under Natural Convection

Abstract

The broken strand fault of overhead transmission lines will cause a local temperature rise. The temperature extreme value point will decay to the normal area, affecting the operation of adjacent lines. In order to study the relationship between the temperature decay distance, the number of broken strands, and the load current of overhead lines under natural convection, a type LGJ-240/30 line is selected as the test object. Destructive thermal cycling tests are performed in the laboratory. The temperature distribution of the outer surface of the line at the fault area is obtained. Based on the theory of heat transfer, the definition of axial temperature decay distance is proposed, and the relationship between the defined distance and each factor is analyzed. The results indicate that axial temperature decay distance is only negatively related to the load current but not to the number of broken strands. This conclusion provides a theoretical reference for fault identification and maintenance of overhead lines.