| 摘要 |
PURPOSE:To enable the interruption and supply of a large amount of electric current and the application of a compact magnet by providing a superconductor connected in series to a contact point and cooling a switchgear and the superconductor with a refrigerant. CONSTITUTION:A low temperature refrigerant 15 like, for example, liquid nitrogen is filled in a cooling vessel 14, thereby cooling a switchgear 20 and a superconductor 13. When a large amount of electric current flows and the critical current of the superconductor 13 is exceeded, the conductor 13 loses superconducting state and comes to have high resistance, thereby limiting the large amount of electric current. When the large amount of electric current flows, an overcurrent relay operates and a tripping spring causes a movable core 3 to be away from a fixed core 2. And a fixed contact point 8A comes to be off a movable contact point 6A, thereby generating an arc 12 between the fixed contact point 8A and the movable contact point 6A. This arc 12 becomes extinct at a zero current level and the current is interrupted. In this case, the arc 12 comes in contact with the refrigerant 15 and is cooled efficiently, thereby enabling the interruption of the current via a short contact point gap. Consequently, a magnet can be made compact. Also, heat generated by the supply of electric current can be removed via the refrigerant 15 and, therefore, a large amount of current can be supplied. |
