The Research And Design On The Shut-off Mechanism Of The Explosive DC Circuit Breaker

The high flat-Top long pulse magnetic field, which is 35.8T/2.5s, has already been achieved in Wuhan National High Magnetic Field Center. The energy of Flat-Top long pulse magnet was provided by battery bank power supply system. In order to get higher magnetic field, power supply system need more battery to provide higher current. Meanwhile, there is need to prepare DC circuit breaker for breaking abnormal high current in new battery bank power supply system, which is a backup protection breaker. The explosive DC circuit breaker was being studied, which come from French LNCMP. It may be used to break abnormal high current in new battery bank power supply system. But there was no shut-off mechanism in the explosive DC circuit breaker. Need to design a shut-off mechanism for DC circuit breaker.Firstly, the principle and process of the DC circuit breaker is studied in this paper. In the DC circuit breaker, aluminum cylinder is contacts of breaker. Depending on the conclusion of analyzing the force of aluminum cylinder when the breaker is running, the design scheme of aluminum cylinder is confirmed. A complete solution for aluminum cylinder and accessories is designed, taking into account machining difficulty high hardness. In this solution, this material of aluminum cylinder is 6061 aluminum alloy, and the size and heat treatment method of the aluminum cylinder is also described in detail.The solution was modeled in order to verify the feasibility and rationality by using COMSOL Multiphysics. Under the maximum current of 100kA/0.1s, thermal stability of aluminum cylinder can meet the design requirements. When the inner wall of the aluminum cylinder is subjected to 5MPa pressure, the aluminum cylinder will be pulled off in the weakest positions. The pressure is lower than the simulative 20 MPa inside the aluminum cylinder. So the design of the aluminum cylinder can be snapped. The fracture shape of aluminum cylinder is gotten by COMSOL Multiphysics emulating after aluminum cylinder being snapped. When the inner wall of the aluminum cylinder is subjected to 20 MPa pressure, the distance of fracture is more than 2.6mm.The experimental result shows that the five fractures in the wall of the aluminum cylinder are formed uniformly, when the circuit breaker is triggered. And the distance of each fracture is about 6mm. The resistance of the main contactor is, 0.008m? and more than 20M? in the conductive state and disconnected state. What's more, the circuit breaker can cut off about 4kA DC current within 1ms. The DC current is provided by battery bank power supply system. In a word, the design of shut-off mechanism is reasonable, and the circuit breaker can work properly. In the future, when the test current and voltage are promoted, the performance requirements of the backup protection breaker of battery bank power supply system can be achieved.