The role of fuse in the circuit includes two aspects: it should be able to operate within the specified time range in case of over-current caused by circuit fault to protect the circuit and personal safety; At the same time, when there is a non-fault instantaneous overcurrent in the circuit, it is not allowed to act at will to ensure the continuous and normal operation of the circuit. These functions are realized by selecting the appropriate fuse fusing characteristics and the appropriate rated current specifications. The basis for selection is the technical data provided by the fuse manufacturer, including "time-current characteristic curve" and "time-energy characteristic curve".
The fusing characteristics and rated current of the fuse are only a name, which can not truly reflect its actual fusing current, fusing time and fusing heat. There are certain differences among different brands of products. For example, the same slow fusing product, brand A may be a little faster than brand B, but certainly slower than brand A's own fast fusing product; Although there are some basic consensus and recognized standards in the industry, the data range of these standards is quite wide. For example, the above brand A products are relatively lower than the lower limit in the standard requirements, while the brand B products are relatively higher than the upper limit, both of which can meet the standard requirements. After all, there are still some differences between the two, so when we replace fuses, in addition to confirming that the rated current is the same, It is better to identify the difference between the two through the characteristic curve to avoid errors or losses caused by performance differences.
Simple and direct replacement may result in insufficient protection performance or abnormal fusing of the fuse and the failure of the whole machine to work. The latter is more likely to occur.