What's the difference between a fuse and a circuit breaker?
Both fuses and circuit breakers can realize short-circuit and overload protection of lines, and their functions are roughly the same, but there are still some differences in many aspects:
1, the working principle is different.
The working principle of fuse is mainly based on the thermal effect of current. When the current exceeds the fixed value, the fuse inside it will cause and blow, thus breaking the circuit and protecting the equipment from being burned out by heavy current. There are many kinds of circuit breakers, and there are also differences in structure and principle. Under normal circumstances, due to excessive current, the trip coil will be excited, prompting the circuit breaker to trip. Of course, the circuit breaker can not only realize automatic operation, but also manually control the opening and closing action of the circuit breaker.
2, the action speed is different
The action speed of fuse can reach microsecond (μs) level, that is to say, its speed is much faster than that of circuit breaker. This ability is usually suitable for installation and use occasions with similar requirements for quick cut-off. The tripping speed of the circuit breaker is millisecond (ms), so it can be seen that the circuit breaker is much slower than the fuse, so it can only be used in occasions where the requirement for tripping speed is not very high.
3. Different use time
After fault protection and melt blowing, the fuse must be replaced. On the contrary, circuit breakers can be reused in most cases.
4. Different places of use
As far as the effect of circuit breaking is concerned, the fuse will be stronger and more thorough than the circuit breaker, so in general, the circuit breaker is installed on the branch line, while the fuse is installed on the main line in most cases to play the role of secondary protection.
5. Different protection methods
Fuse fuse protection, after the fault phenomenon is eliminated, it is necessary to replace the melt again to restore power supply, which is inconvenient for maintenance. The protection mode of circuit breaker is tripping. After troubleshooting, normal power supply can be restored by simply closing it, so it will be much more convenient for maintenance and recovery than fusing.
Function of circuit breaker
The function of circuit breaker is to cut off and connect the load circuit, cut off the fault circuit, prevent the accident from expanding and ensure the safe operation.
Function of fuse
The function of the fuse is to act as the melt itself. When the current is too high or exceeds the load current, it can fuse the electrical components that prevent the circuit from being damaged. This is different from the breaking current of the circuit breaker, and its function can be understood through the fuse commonly used in our family. And the circuit breaker is basically used as the main switch. The fuse is installed in the circuit.
Circuit breakers and fuses have similar functions. Some friends will use circuit breakers instead of fuses. Generally speaking, circuit breakers are more convenient and economical than fuses, and can be replaced. But in some cases, circuit breakers cannot be used instead of fuses.
In many line equipment, it is unsafe and incorrect not to install fuses, such as the control and protection of elevators, which require the compulsory use of fuses; And in some cases, because the tripping speed of the circuit breaker can not meet the requirements, it may lead to fire.
Therefore, circuit breakers can't replace fuses, and fuses are still used in some places that require high safety performance.