Cables and conductors protection, part II: overhead conductors

One of the applications of fuses is the overhead lines protection. Usually the fuse is selected taking into account selective coordination, thus the overhead line is not protected against overheating, which causes two application limits, the mechanical strength weakening, and the minimum distance to earth. The conductor over-temperature for steady-state conditions can be assessed by using a simple exponential equation. A simplified solution is proposed, which gives for each current value the time needed to reach the limit temperature, being a time-current characteristic. The over-temperature as time function was assessed, in order to calculate the useful life lost and the conductor creep. This simple methodology allows a more rational fuse selection for the bare overhead conductor protection.