In today's work and production, there is a phenomenon in both industrial and civil power distribution systems, that is, the frequency of use of low-voltage fuses is less and less, and it seems that everyone is more willing to use them in more and more cases. low voltage circuit breaker instead. And this is not a single phenomenon. In many distribution boxes, low-voltage circuit breakers are gradually replacing fuses.

1. Reason

Fuses are single use. Once the fuse is blown, the fuse must be replaced, which relatively increases the maintenance cost. The circuit breaker can be used repeatedly, and after the circuit breaker is activated, as long as the fault is eliminated, the air circuit breaker can be put into operation, and the application and maintenance are more convenient!

2.Difference

They both have roughly the same functions, but there are still many differences in many places, including differences in protection methods, action speeds, times of use, and working principles. The differences between fuses and circuit breakers are as follows:

(1). The difference between fuse and circuit breaker protection methods:

①The protection method of the fuse is in the form of fusing, and when the fault phenomenon is eliminated, it is necessary to replace the fuse to restore the power supply, so it is not convenient for maintenance.

②The protection method of the circuit breaker adopts the form of tripping. After the fault is eliminated, the normal power supply can be restored only by the closing action, so it is much more convenient than the fuse in terms of maintenance and recovery.

(2). The difference between the action speed of the fuse and the circuit breaker:

①The fusing action speed of the fuse can reach the microsecond (μs) level, that is to say, its speed is much faster than that of the circuit breaker. Install and use.

② The tripping action speed of the circuit breaker is in milliseconds (ms), which can be seen to be much slower than that of the fuse, so it can only be used in situations where the cut-off speed requirement is not very high.

(3). The difference between the number of times of use of fuses and circuit breakers:

①The fuse must be replaced after performing a fault protection and the fuse has been blown. On the contrary, the circuit breaker can be reused in most cases.

②The effect of the circuit breaker The fuse will be stronger and more thorough than the circuit breaker. Generally, the circuit breaker is installed on the branch line, and the fuse is installed on the main line for secondary protection in most cases effect.

(4). The difference between the working principle of fuse and circuit breaker:

①The working principle of the fuse is mainly based on the thermal effect of the current. When the current exceeds the fixed value (it needs to know that the fixed value of different fuses is also different), the internal fuse will cause the occurrence and fuse to achieve breaking. circuit, and play a role in protecting the equipment from being burned out by the high current.

②There are many types of circuit breakers and there are differences in their structural principles. Usually, the excitation of the trip coil will cause the circuit breaker to perform the trip action because the current is too large. Of course, the circuit breaker can be operated not only automatically but also manually. To control the opening and closing action of the circuit breaker.

3. Choice

1. Low voltage circuit breaker. 

It is used for the load current protection of the main power supply end; it is used for the load current protection of the main line and branch line of the distribution line; it is used for the load current protection of the end of the distribution line. When overload, short circuit, or voltage loss occurs in the line, the low-voltage circuit breaker trips instantaneously to cut off the power supply to protect the line safety. The leakage protection residual current circuit breaker installed in the line is used for personal electric shock protection.

2. Fuse.

(1) It is used for overload protection of load current in the line and short circuit between phases and phase to ground.

(2) A fuse is a protective electrical appliance. When the current exceeds the fixed value and passes a sufficient time, the melt melts and the circuit connected to it is disconnected, so as to protect the circuit and equipment from overload or short circuit.

(3) Through a relatively simple analysis, it can be known that circuit breakers and fuses should be installed in low-voltage electrical installations, whether it is industrial power in factories, mines or households. Anyone who is an electrician knows that electrical work must seriously abide by the "Regulations for Low-Voltage Electrical Installations".

(4) There are two chapters in "Lower Regulations" that specifically formulate the installation specifications for main switches (circuit breakers) and fuses. In the actual circuit installation, attention should also be paid to the matching of the circuit breaker and the fuse and the matching of the wire, namely:

① The rated fusing current of the fuse installed in the circuit must be greater than or equal to 1.2 to 1.3 times the rated current of the circuit breaker.

②The melt current of the fuse is less than or equal to 0.8 times the safe current carrying capacity of the wire conductor.

③In layman's terms, the melt current of the fuse should be greater than the rated current of the circuit breaker and less than the safe current carrying capacity of the wire.

④ The rated current of the circuit breaker must be greater than or equal to the line current, generally 1.2 times the line load current. And depending on the nature of the line load (such as electric heating) to make appropriate adjustments. However, the rated current of the selected circuit breaker must be less than the melt current of the fuse. There are also many circuit devices without fuses, which are unsafe and incorrect. When there is a fault in the line, it is very suitable to cause a fire. This has been related to the failure to install or wrongly install fuses in previous fire accidents. There are also many lessons. Therefore, fuses should be installed in home decoration and installed with circuit breakers. Safety first must not be sloppy.