| 摘要 |
PURPOSE:To protect a thyristor by a method wherein a reactor is formed by a superconductive material, the superconductive material is brought to a superconductive state on a stationary state and loss is prevented completely, and the superconductive material is brought to a normal conductive state when a surge intrudes and operated as the reactor. CONSTITUTION:An AC-DC converter has thyristors 1, a module 2, a potential coupling line 5, a current input line 3 and an output line 4, and superconductors 8 are bonded in parallel with reactors 7 at both ends of the thyristors, thus shaping a protective device. Consequently, currents do not flow through the reactors 7 under the state in which the conductors 8 juxtaposed to the reactors 7 are in a superconductive state, thus extremely reducing impedance. When surge currents intrude at one time and exceed the critical currents of the conductors 8 and turn normally conductive, the resistance of the conductors 8 is increased suddenly and currents flow through the reactors 7, and the resistance functions as induced reactance. When surge currents are removed, the conductors 8 are made superconductive again. |
