When the current flows through the conductor, the conductor will generate heat due to the certain resistance of the conductor. And its calorific value will follow the formula Q=0.24I2RT; where Q is the calorific value, 0.24 is a constant, I is the current flowing through the conductor, R is the resistance of the conductor, and T is the moment when the current flows through the conductor; according to the formula It is not difficult to understand the working principle of current fuse.

After the material and shape of the current fuse are determined, its resistance R is relatively determined (provided that its temperature coefficient of resistance is not considered). When current flows through it, it will heat up, and its heat will continue to increase over time. The size of current and resistance determines the speed of heat dissipation. The structure of the current fuse and its device determine the speed of heat dissipation. If the rate of heat generation is lower than the rate of heat dissipation, then the fuse will not be blown. . If the rate of heat generation and the rate of heat dissipation are equal, it will not melt for a long period of time. If the rate of heat generation is greater than the rate of heat dissipation, then more and more heat will be dissipated. Because it has a certain specific heat and quality, the increase in its heat is reflected in the increase in temperature. When the temperature rises above the melting point of the current fuse, the current fuse will blow. This is the working principle of current fuse.