We all know that when current flows through a conductor, the conductor will heat up due to the existence of a certain resistance in the conductor. And the calorific value follows this formula: Q=0.24I2RT; 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 time for the current to flow through the conductor; according to this formula It is not difficult for us to see the simple working principle of the fuse.
When the material and shape of the fuse are determined, its resistance R is determined relatively (if its temperature coefficient of resistance is not considered). When current flows through it, it heats up, and it heats up over time. The size of the current and resistance determines the rate of heat generation. The structure of the fuse and the condition of its equipment determine the rate of heat dissipation. If the rate of heat generation is less than the rate of heat dissipation, the fuse will not be blown. If the rate of heat generation is equal to the rate of heat dissipation, it will not fuse for a long time. If the rate of heat generation is greater than the rate of heat dissipation, more and more heat will be generated. And 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 fuse, the fuse will blow. This is how fuses work. We should know from this principle that you need to carefully study the physical properties of the materials you choose when planning to make fuses, and make sure they have the same geometric standard. Because these factors play a crucial role in the normal operation of the fuse. Also, when you use it, be sure to install it correctly.
For the function of the fuse, the influence of the external temperature on it is also very direct. In addition to the external temperature, there are many factors that will affect the temperature change on the fuse melt, which will also affect the function of the fuse.
An example is as follows:
1. Internal resistance of the fuse: The initial internal resistance of the fuse or the increase of the internal resistance after aging will affect the change of the heat dissipation conditions of the fuse, after all, the fuse time will be faster.
2. The connection of the fuse: The connection inside the fuse is also a very important factor. If the resistance of the contact at the location of the connection increases, it will also affect the function of the fuse.
3. The surrounding heat dissipation conditions: the distance between the fuse and the internally connected components, the density of the arrangement of each component in the circuit, the length of the cross-sectional area between the connecting wire and the PC board, etc. are all related.
In addition to the reasons mentioned above, the improper selection of some parameters of the fuse will also affect the actual function of the fuse. Therefore, it is safe to choose a suitable fuse.
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