| 摘要 |
PURPOSE:To make a current limiting action together with a rapid breaking of circuit possible by exciting an electro-magnetic coil through the voltage applied to both ends of a current limiting member following the transition to a normal conductive state in the current limiting member simultaneously with said transition so that a movable contact is rapidly dissociated from a fixed contact. CONSTITUTION:If an excess current, such as short-circuit current or the like, flows in a circuit, the small cross-sectional part of a current limiting member 12 induces a superconductive breakdown and undergoes a transition from a superconductive state to a normal conductive state. In addition, as a result of the transition to the normal conductive state, a resistance appears to produce an electric current, and consequently, a transition coil 3 is excited, and the transition to the normal conductive state spreads rapidly all over the current limiting member 12 so that the excess current is current-limited, and at the same time, the electric current is commutated into an electromagnetic repulsion coil 13 which is connected in parallel with the current limiting member 12. And further, the electric current rapidly flowing in the electromagnetic repulsion coil 13 causes an excess current to flow in a conductive disc 14, and the conductive disc 14 receives the resiliency downward so that a movable contact 15 is dissociated from a fixed contact 16. Thereby, the electric current which is current-limited can be cut off. |
