When the fuse is energized, due to its own resistance, the electric energy is converted into heat to make the melt heat. At the same time, the heat generated by the current radiates to the surrounding environment through the melt and the shell, and dissipates heat through convection and conduction. When the fuse passes the allowable operating current, the heat dissipated and the heat generated reach a balance. The heat will not accumulate in the melt and increase the temperature of the melt, so the fuse will not reach its melting point and blow. When the current passing through the fuse reaches a certain value, the heat converted from electric energy increases, and the heat dissipation speed cannot keep up with the heating speed. This heat will gradually accumulate in the melt and increase the temperature of the melt. When the temperature reaches the melting point of the fuse When the fuse begins to melt and continues to absorb heat to further melt and become liquid, then the temperature of the fuse further rises to the vaporization point to form an arc. The arc is a gas-free discharge phenomenon. The strength of the arc is related to the voltage of the circuit. The higher the arc, the stronger the rated voltage of the fuse. The main difference is that the circuit voltage that the fuse can withstand when the fuse is blown is different. The fuse cannot be used in a circuit higher than its rated voltage, because the arc is not easy to extinguish when the circuit voltage is higher than the rated voltage of the fuse. In addition, the strength of the arc is also related to the current in the circuit. The greater the current, the stronger the arc. If the arc cannot be extinguished in time, not only the circuit cannot be cut off, but other components in the circuit may also be burned, which may lead to fires and accidents. High explosion-proof fuse is used to install explosion-proof sand to extinguish the arc. After the arc is extinguished, the fuse will actually cut off the current to protect other equipment.