Villamos Berendezes Es Keszuvek Muvek

Zoltan Szemerey

Janos Melis

Arpad Karpat

Tibor Csizy

A fuse-element for electric fuses is shaped as a metal strip with one or more zones of diminished cross-section. The temperature rise conditions of the fuse-element and of its zones of diminished cross-section can be established and evaluated in combination and--based on these data--a fuse-element can be designed the temperature distribution characteristics of which include different local peak values and the spots where such peak values develop can be set in a manner that the whole fuse-element consists of two parts as far as the temperature distribution is concerned, i.e. a first part where this distribution is in accordance with a steady state distribution (the highest current value still failing to cause any melting), and a second part where the temperature rise distribution determines the character of the melting process, this being the so-called transient distribution characteristic. Such a design facilitates an essentially more exact setting of the rated currents and the desired melting time/current characteristics. The solution of this task, according to the invention, consists in that at least one of the zones of diminished cross-section, extending longitudinally along a part of the metal strip at which the operating temperature reaches relatively small values, is of a smaller cross-section than the remaining zones and exceeds the latter ones in length. The smallest cross-section is preferably arranged as a marginal zone, i.e. the zone is disposed next to one end of the fuse-element.

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Budapest, Hungary

Zoltan Szemerey