Construction of HRC fuse:
HRC fuse mainly consists of heat resisting ceramic body. The current carrying element is compactly surrounded by the filling powder. Filling material acts as an arc quenching and cooling medium when the fuse element blows off due to excessive heat generated under abnormal conditions. 
Working:
Under normal conditions, the fuse element is at a temperature below its melting point. Therefore, it carries the normal current without overheating. When a fault occurs, the current increases and the heat produced is sufficient to melt these elements. Fuse element melts before the fault current reaches its first peak value.
Vaporized metal /fuse element chemically reacts with filling powder and results in the formation of high resistance substance that helps in quenching the arc.
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