The first fuse was invented by Thomas Edison more than a hundred years ago, and was originally used to protect expensive incandescent lamps, which were very expensive due to the lack of industrial technology at that time.

The purpose of a fuse is: when a circuit malfunction or abnormality occurs, it is accompanied by a rising current, and the rising current may damage some important or valuable components in the circuit, and may also burn the circuit or even cause a fire. If the circuit is correctly installed fuse, then, the fuse will be in the current anomalies rise to a certain height and a certain time, the fuse itself fuses to cut off the current, so as to play a role in protecting the safe operation of the circuit.

General fuse consists of three parts:

One is the melt part, it is the core of the fuse, when it fuses to cut off the role of the current, the same class, the same specification fuse melt, material to be the same, geometric size to be the same, as small as possible and to be consistent with the value of the resistance, and most importantly, the fusible characteristics of the same;

The second is the electrode part, usually there are two, it is an important part of the fuse and circuit connection, it must have good electrical conductivity, should not produce obvious installation contact resistance;

Third is the support part, the fuse of the fuse are generally thin and soft, the role of the support is to fix the melt and make the three parts into a rigid whole for installation, use, it must have good mechanical strength, insulation, heat resistance and flame retardant, should not produce fracture, deformation, combustion and short-circuit phenomena in use;

Fuses used in electric circuits and high-power equipment not only have the three parts of a normal fuse, but also have an arc extinguishing device. Because the circuit protected by this type of fuse is not only a large operating current, and when the fuse fuses the voltage at both ends is also very high, there will often be a melt (fuse) or even vaporized, but the current has not cut off the phenomenon. The reason for this is that in the instant of fusing, under the action of voltage and current, an arc is drawn between the two poles of the fuse.

The arc extinguishing device must have strong insulation and good thermal conductivity, and negative electrical properties. Quartz sand is commonly used as an arc extinguishing material. In addition, there are some fuses have a blowing indicator device, its role is when the fuse action (blowing) after a certain appearance of its own changes, easy to be found by the maintenance staff, such as: luminous, color changing, pop-up solid indicator, and so on.