First, let’s analyze the function of low voltage circuit breaker and fuse in low voltage electrical circuit ：
1. Low Voltage Circuit Breakers
It is used for load current protection at the total power supply end, for load current protection at the trunk and branch ends of distribution lines, and for load current protection at the end of distribution lines.
When overload, short circuit, or voltage loss occurs in the line, the instantaneous trip of low-voltage circuit breaker cuts off the power supply to protect the safety of the line.
Residual Current Circuit Breaker Used for Personal Shock Protection
It is used for overload protection of load current in line and short circuit protection between phase and phase and relative ground.
A fuse is a protective device. When the current exceeds the fixed value and passes through enough time, the melt melts, and the circuit connected to it is disconnected, which provides overload protection or short circuit protection for the circuit and equipment.
Through a simple analysis, it can be known that circuit breakers and fuses should be installed in low voltage electrical devices, whether for industrial use or household use.
Do electrician profession all know: Electrical work must seriously comply with the “Low Voltage Electrical Device Regulations”. There are two chapters in the “Low Voltage Electrical Device Regulations” which specially formulate the installation specifications of main switch (circuit breaker) and fuse.
The matching of circuit breaker and fuse and the matching of wire should also be paid attention to in the actual circuit device.
The rated fuse current of the device fuse in the circuit must be greater than or equal to 1.2 to 1.3 times of the rated current of the circuit breaker.
The melt current of the fuse is less than 0.8 times of the safe current of the wire conductor.
Generally speaking, the melt current of fuse should be larger than the rated current of circuit breaker and less than the safe carrying capacity of conductor.
The rated current of circuit breaker must be greater than or equal to the line current, and the line load current should be 1.2 times as much as the line load current. It can also adjust the line load properly according to the nature of the line load, such as electric heating. But the rated current of the circuit breaker must be less than the fuse melt current.
In addition, there are many circuit devices without fuses, which are unsafe and incorrect. When there is a fault in the line, it is very easy to cause fire. In the past fire accidents, fuses were not installed or misfitted. There are many lessons to be learned. Therefore, fuses and circuit breakers should be installed in the home decoration. Never be careless and safe first.
Post time: Apr-11-2021