Why Must The Fuse Current Be Limited To Not Exceed The Rated Current Of The Fuse?

In electrical design and installation, the drop out fuse fuse serves as a fundamental overcurrent protection element. Its rated current defines the maximum stable current that the fuse element can withstand under normal operating conditions. If the fuse current exceeds this rated value, the metal inside the fuse wire will melt due to excessive heat accumulation, causing circuit interruption.

The working principle of a fuse is based on the thermal effect: heat is generated when current flows. If the current remains above the rated value, the temperature of the metal wire will rise to its melting point, causing it to melt.

If the fuse current exceeds the rated current, under normal circumstances, the fuse may blow prematurely, leading to frequent circuit interruptions and affecting the stable operation of equipment. In severe cases, it may fail to interrupt fault current in time, causing equipment damage or fire risk.