Views: 5 Author: Site Editor Publish Time: 2022-12-22 Origin: Site
Today we will introduce the working principle of the fuse links in detail. When the fuse link is connected to the circuit, the melt is connected in series in the circuit, and the current of the load flows through the fuse link. When the circuit is short-circuited, the short-circuit current in the circuit is very large.
According to Joule's law, the calorific value per unit time is proportional to the square of the current. Therefore, the large current passing through the melt causes the heat generation to increase dramatically. When it reaches the melting temperature of the molten metal, it will fuse itself, and then cut off the fault circuit to play a protective role. The action characteristic of the fuse is an ampere-second characteristic, that is, the larger the current, the shorter the fusing time, also called inverse time limit, which is very suitable for short-circuit protection.
Then some people may wonder, why can't fused link be used for overload protection in general? According to its working principle, the fuse is not very sensitive to slight overload, and it takes a long time for the melt to blow. Therefore, for occasions with high requirements for overload protection, it is best to use an adjustable thermal relay or a device with current monitoring for protection.
Below we introduce the difference between fuses and circuit breakers in detail.
1. The fuse is cheap and small in size. Circuit breakers are expensive and bulky.
2. To develop in the direction of remote control and intelligence, after the internal melt of the fuse is damaged, it needs to be replaced. After the circuit breaker is protected, it does not need to be replaced, and it can be manually reset, saving maintenance time.
3. The short-circuit fusing speed of the fuse can reach the level of microseconds (μs), and the speed of the circuit breaker is at the level of milliseconds (ms). The circuit breaker can easily fuse the maximum limit short-circuit current. Strong breaking ability. The breaking limit short-circuit current of the circuit breaker is small.
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