Investigating Dynamic Characteristics of Cavitation in Insulating Oil Microgaps Under Vibration: Theoretical Analysis and Experimental Observation

ABSTRACT The internal pressure fluctuations caused by vibration in oil‐immersed electrical equipment can initiate bubbles within narrow oil gaps, reducing the electrical strength of equipment and giving rise to the problem of abnormal gas production in oil‐immersed equipment. This study mainly investigates the dynamic characteristics of cavitation in insulating oil microgaps under varying vibration conditions. A microgap model with vibration is constructed based on fluid mechanics, the fluid pressure within the microgap is derived, and the maximum negative pressures caused by vibration under varying vibration conditions and geometric structures of the insulating oil microgap are analysed. Subsequently, combined with the theories of bubble dynamics, the dynamic processes of the bubble within the microgap during a single vibration cycle under varying vibration conditions are analysed, and the influence of vibration intensity and frequency on the dynamic characteristics of the bubble is also discussed. Finally, the bubbling phenomenon and cavitation processes within the microgap under varying vibration conditions are observed and analysed using an experimental platform of microgap vibration. A better understanding of the development process of cavitation within the microgap structure under vibration is achieved. Furthermore, this study also provides theoretical support for the insulation risk assessment of the microgap structure under vibration and the design optimisation of the internal structure of oil‐immersed electrical equipment.