When a fuse is energized, its own resistance converts electrical energy into heat, causing the melt to heat up. At the same time, the heat generated by the current also radiates to the surrounding environment through the melt and shell, and dissipates heat through convection and conduction. When a fuse passes through the allowable working current, the heat emitted and generated reaches a balance, and the heat does not accumulate in the melt, causing the temperature of the melt to rise. Therefore, 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 electrical energy increases, and the heat dissipation rate cannot keep up with the heating rate. This heat gradually accumulates on the melt, causing the temperature of the melt to rise. When the temperature reaches the melting point of the fuse, the fuse begins to melt and continues to absorb heat, further melting into a liquid state. Subsequently, the temperature of the fuse further increases to the vaporization point, forming an arc, which is a phenomenon of gas free discharge, The strength of the arc is related to the voltage of the circuit. The higher the voltage, the stronger the arc. The main difference in the rated voltage of the fuse is the circuit voltage it can withstand when it blows. The fuse cannot be used in circuits above its rated voltage because the arc is not easily extinguished 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, and the greater the current, the stronger the arc. If the arc cannot be extinguished in a timely manner, it may not only fail to cut off the circuit, but may also burn other components in the circuit, leading to a fire and accidents. High explosion-proof fuses use the addition of explosion-proof sand to extinguish the arc. After the arc is extinguished, the fuse truly cuts off the current, achieving the purpose of protecting other equipment.
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