Structure and characteristics of fast fuse

Fast fuse is a kind of fuse, which is mainly used for short circuit protection of semiconductor rectifier elements or rectifier devices. Because the overload capacity of semiconductor components is very low. It can only withstand large overload current in a very short time, so the short circuit protection is required to have the ability of fast fusing. The structure of the fast fuse is basically the same as that of the sealed fuse with filler, but the melt material and shape are different. It is a variable cross-section melt with a V-shaped deep groove punched from a silver sheet.

In addition to the metal wire with a certain shape, the fuse of the fast fuse will also be marked with a solder joint of a certain material on it, so as to quickly disconnect the fuse under overload.

Structure of fast fuse

The fuse is composed of six parts: magnetic case, conductive plate, melt, quartz sand, arc extinguishing agent and indicator. The melt is made of pure silver, rectangular sheet in shape, and has a round hole and narrow neck

Arc extinguishing principle of fast fuse

The melt of the fast fuse is made of pure silver. Because of the low resistivity, good ductility and good chemical stability of pure silver, the melt of the fast fuse can be made into a thin sheet with a round hole and narrow neck structure. When a short circuit fault occurs, the current density at the narrow neck is high, so the narrow neck is fused first and separated into many small sections by quartz sand. In this way, the arc formed due to melt fusing is divided into many small segments by quartz sand, the arc current is small, the distribution space is small, and it is easy to be absorbed by the arc extinguishing agent. As quartz sand is insulated, an insulator is formed immediately after the arc is extinguished