Self-loosening Process Simulation of Bolted Joints in 12kV Vacuum Circuit Breakers under Vibration

The circuit breaker is an important part of control and protection in the power system. Mechanical failure is the main fault of circuit breakers, and the loosening of fasteners is one of the typical mechanical faults. The self-loosening of bolted joints is closely related to the vibration, especially transverse vibration. There is strong vibration while the circuit breakers are opened and closed. In this paper, a finite element model is established to simulate the self-loosening process of bolted joints in 12kV vacuum circuit breakers under vibration. The relationship between the self-loosening process and different vibration conditions is discussed. The transverse vibration conditions are changed by applying different load amplitude, different initial preload and different surface friction coefficient. The result has guiding significance for the understanding of bolted joints' selfloosening and the loosening fault diagnosis of circuit breakers' fasteners.