Longitudinal Thermomechanical Behavior.

Studies have been carried out to try and understand the thermomechanical behavior of the MV network cable (HN 33-S-23) when it is subjected to operational conditions leading to conductor temperatures above 90 degree C. In these studies, tests have been made on samples of short and long lengths, on mass produced cables and on prototypes. These tests have enabled us to grasp the essential phenomena, such as shrinking of the insulation and buckling of the metal screen. It may be affirmed that the shrinkage is very small and that it is limited to the terminations and that above 120 degree C at the conductor the stresses connected with the differential expansion between core and screen can cause the aluminum screen to buckle: this is characterized by the appearance of annular folds.