| 摘要 |
In the past, a power fuse need be replaced after the current limiting operation and cannot be repeatedly used. To solve this problem, there has been proposed a permanent fuse or the like which uses an alkaline metal having a low melting point such as Hg, K, Na, etc. These are harmful to human body, and since they are completely vaporized, an insulated layer of a vessel cannot be removed, thus giving rise to a difficulty toward higher voltage. The present invention makes best use of characteristic of carbon which sublimates. A plurality of boundary layers of carbon lumps are disposed in series or in series and parallel, and electrode potential drops at the time of large current and potential drops of arc column under high atmosphere presssure which produces for a short period of time are utilized to effect current limiting. Despite the fact that materials used comprise carbon, they are harmless to human body, and since the potential drop is utilized, a large insulated layer of the vessel can be used to facilitate the formation of higher voltage. Since the carbon lumps are not fused, repeatable use becomes possible.
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