Working principle of fuse

The working principle of fuse is mainly based on the thermal effect of current and the physical properties of metal conductor expansion due to heat. When the circuit is working normally, the heat generated by the current passing through the fuse (generally a metal wire or metal sheet) is balanced with the heat dissipated by the fuse to the surrounding environment. At this time, the fuse remains solid and the circuit is unobstructed. However, once an abnormal situation such as a short circuit or overload occurs in the circuit, the current will increase sharply, far exceeding the rated current value of the fuse. At this time, the heat on the fuse accumulates rapidly and the temperature rises sharply. When the temperature reaches the melting point of the fuse, the fuse begins to melt and form a fracture, thereby cutting off the circuit and protecting the electrical equipment. ‌

The application scenarios of fuses are very wide. They are widely used in high and low voltage power distribution systems and control systems as well as electrical equipment as short circuit and overcurrent protectors. Fuses have the characteristics of high breaking capacity, short-circuit large current limiting capacity and fast breaking speed, and are suitable for various electrical energy systems.

‌Fuse types‌ mainly include the following categories:

‌Guide rail fuse‌: mainly composed of fuse and mounting base, fixed to the bottom plate or mesh plate of the distribution box through the guide rail.

‌Porcelain plug-in fuse‌: composed of porcelain base, porcelain cover, contact, asbestos and fuse, easy to replace.

‌Spiral fuse‌: composed of porcelain base, porcelain cap, porcelain sleeve and fuse tube, suitable for branch circuits with large short-circuit current.

‌Enclosed tube fuse‌: There is a filled enclosed tube fuse, suitable for branch circuits with large short-circuit current or places with flammable gas.