high voltage fuse-fundamental



CurrentlimitingHVfuse types: back-up (or partial range) fuse links, which will interrupt any current from their rated breaking capacity down to a minimum breaking current specified by the manufacturer; and general purpose fuse links, which will interrupt all cur rents f rom rated breaking capaci ty down to a current that will melt the elements within one hour. A third type is the full range fuse. This term applies to fuse links that can interrupt any current below t h er a t e db re a k i n gc a p a c i t yt h a tm e l t st h ef u s e elements satisfactorily. Current limiting back-up fuse links are the closest in construction to LV cartridge types. However, a longer strip element with many more restrictions is necessary to produce the large number of series arcs needed to interrupt a high voltage. Fuse manufacturers achieve this by coiling the element around a ceramic core with a star shaped cross section. In this way, a 1m long element can be fitted into a 250mm long fuse body. If the adjacent coils are too close, there will be a flashover between them and this sets a practical limit on how long an element can be crammed into a particular cartridge, and how many elements can be used in parallel.

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