What is the main function of a fuse?

A fuse is commonly known as an insurance wire or an insurance tube. The earliest fuse was invented by Edison over a hundred years ago. Due to the underdeveloped industrial technology at that time, incandescent lamps were very expensive. Therefore, initially, it was used as a fuse to protect the expensive incandescent lamps. 

Fuses protect electronic equipment from overcurrent damage and also prevent serious damage to the equipment caused by internal faults. 

Therefore, each fuse has a rated specification. When the current exceeds the rated specification, the fuse will melt. When a current between the normal non-melting current and the rated breaking capacity specified by the relevant standards acts on the fuse, the fuse should work satisfactorily and will not endanger the surrounding environment. 

The expected fault current of the circuit where the fuse is installed must be less than the rated interrupting capacity current specified by the standard. Otherwise, when a fault occurs and the fuse melts, there will be phenomena such as continuous arcing, ignition, melting of the fuse, fusion of the contact parts together, and inability to identify the fuse marking. Of course, the interrupting capacity of inferior fuses does not meet the requirements of the standard, and using them will also cause hazards. 

The protective components used in electronic devices, apart from fuse resistors, also include ordinary fuses, thermal fuses and self-recovery fuses, etc. These protective components are generally connected in series in the circuit. When abnormal phenomena such as overcurrent, overvoltage or overheating occur in the circuit, they will immediately melt and play a protective role, preventing the fault from further expanding.