Insulation–Vibration Dynamics Model and Experimental Investigation of Cable Gas‐Insulated Switchgear Terminations

Numerous breakdowns in cable gas‐insulated switchgear (GIS) terminations stem from inadequate insulation and interfacial stresses. However, existing diagnostic techniques, such as partial discharge detection and microwave detection, are highly susceptible to electromagnetic interference, or their diagnostic signals are often attenuated by the shielding effect of the metallic enclosure. To address these limitations, this study proposes a nonintrusive online vibration‐based approach to assess the interfacial stress state of internal insulation. An insulation–vibration dynamic model that combines lumped‐parameter and distributed‐parameter formulations is established. Furthermore, a 110 kV cable GIS termination vibration test platform is built to emulate interfacial stress degradation by adjusting the spring preload. The effects of insulation defects on the spatial distribution of vibration signals are experimentally measured. Both simulation and experimental results reveal that insufficient interfacial insulation stress reduces the equivalent stiffness and alters the vibration modal characteristics, thereby attenuating the cable vibration near the tail tube. By implementing nonintrusive vibration detection, this study enables the identification of internal insulation risks induced by insufficient interfacial stress, facilitating proactive prevention of insulation failure and enhancing early‐warning capabilities prior to discharge.