Vibration-Based Detection of Cable Bending in Cable GIS Terminations via Experimental Measurements and Interface Stress Simulation

Cable GIS terminations are prone to insulation defects induced by abnormal internal stress and strain, due to their complex internal structure, latent defects, and sensitivity to installation quality. One typical manifestation of such abnormal mechanical states is internal cable bending, whose influence on the vibration response of cable GIS terminations remains insufficiently understood. To address this issue, this study proposes a vibration based method for detecting abnormal stress-strain conditions at insulation interfaces, enabling early identification of hidden insulation defects. First, vibration theory and simulation models are combined to examine how internal cable bending influences interfacial insulation pressure and the corresponding vibration response. Subsequently, a vibration testing platform for 110-kV cable GIS terminations is established to measure and analyze the vibration characteristics under normal and simulated abnormal stress-strain conditions, with the latter induced by cable bending. Finally, the vibration characteristics are evaluated using time domain and frequency-domain indicators. The results demonstrate that internal cable bending leads to non-uniform stress distributions at the insulation interfaces between the bushing, stress cone, and cable. The cable-end vibration, which is typically the most pronounced under normal conditions, is significantly suppressed, accompanied by a noticeable shift of the vibration signal toward the lower-frequency domain and an increase in damping. These findings establish a vibration response characterization framework for cable bending defects and provide a basis for non-intrusive condition assessment of cable GIS terminations.