In situ defect recognition analysis on long cables through nondestructive reflectometry and dielectric spectroscopy methods: a comparison

In this paper the aging through high temperature of 10-meter long coaxial cables and its change in electrical properties have been investigated through non-destructive electrical techniques i.e. dielectric spectroscopy and time domain reflectometry. Both techniques allow changes of electrical properties to be revealed with aging, however, the coupling of these two techniques permits an effective cable aging assessment allowing also the recognition of local defects. Indeed, it has been demonstrated that dielectric spectroscopy is more sensitive when the cable is globally aged, while time domain reflectometry, in addition to a global investigation, can also single out aging occurring in limited portion of cable insulation (local aging).