| 摘要 |
PURPOSE:To obtain a current limiting device which hardly generates heat at the time of normal operation by connecting a superconducting element in parallel with a permanent fuse. CONSTITUTION:When an abnormal large current flows due to a short-circuit accident or the like, a detector, not shown, detects it to output a switching signal to a terminal 6. Then, a control coil 5 is energized, a large resistance is generated in a superconducting element 4 in which its superconducting state is broken by its magnetic field, and an accident current is commutated to a permanent fuse 1. Alkaline metal in the fuse 1 is vaporized by the Joule heat of the large current in a short time, and its resistance value abruptly rises. As a result, since the fuse 1 becomes a high resistance, the accident current is branched to a resistor 2 to maintain the current limiting operation of the accident current. A circuit breaker, not shown, provided at a load or power source side is released in parallel with the current limiting operation to remove an accident point. Thus, the accident current is commutated to the fuse 1 out of a tank 3 thereby to generate no heat in both the fuse 1 and the element 4 during normal operation. |
