Fuse element, which is the core of the fuse. The fuse element is equivalent to a special wire connected in series in the circuit. When the circuit is short-circuited or overloaded, the current is too high and the fuse melts due to overheating, thus cutting off the circuit. Therefore, for high-voltage fuse materials, the requirements are low melting point, stable characteristics, easy to melt, easy to extinguish the arc.

The materials used to make high voltage fuse cores are copper, silver, zinc, lead, lead-tin alloy, etc. The melting points of these materials are also different, so different currents require different materials, and their melting temperatures correspond to 1080°C, 960°C, 420°C, 327°C, and 200°C, respectively. The use of these different materials is described below:

① Metals such as zinc, lead and lead-tin alloys have lower melting points but higher resistivity. Therefore, the cross-sectional area of the fuse element used is larger, and more metal vapor is produced when melting, which is not conducive to arc extinguishing. Mainly used in circuits below 1kV.
② copper, silver melting point is higher, but the resistivity is smaller, conductive, good thermal conductivity. Therefore, the cross-sectional area of the fuse element used is smaller, less metal vapor produced when melting, easy to extinguish the arc, can be used for high-voltage, high-current circuit. However, if the passing current is too large and the temperature is too high for a long time, it is easy to cause damage to other components within the fuse.

To make the fuse element to melt quickly, there must be a larger current flow, otherwise it will prolong the melting time, not conducive to the protection of equipment. In order to eliminate this shortcoming, often in the copper or silver melt soldered on the tin or lead ball to reduce the melting temperature of the melt to improve the protective properties of the melt.

For the same type, specifications of the fuse, the material should be the same, the geometry should be the same, the resistance value as small as possible and consistent, and most importantly, the fusing characteristics should be consistent.