Electrical fire is the "first killer" that threatens people's life and property safety. According to statistics, nearly half of the fires in my country are caused by improper use of electricity. With the improvement of the economic level, more and more attention has been paid to electrical safety, and people have begun to choose to install circuit breakers to protect the safety of electricity. However, the traditional circuit breaker only protects against overload and short circuit in the electrical circuit, but cannot detect the fault arc, the culprit of electrical fires.
Due to poor line contact or insulation damage, a "bad arc" with high energy and high temperature - fault arc is generated in the electrical line, which is not easy to be found but easily causes equipment damage and even fire.
1. The current waveform is rich in high-frequency noise
2. There is a voltage drop on the fault arc
3. The current rising speed is usually larger than the normal state
4. There is an area where the current is close to zero in every half cycle, which is called "current zero area"
5. The voltage waveform is close to a rectangle, and the rate of change in the current zero zone is larger than that at other times, and the maximum value is when the current crosses zero.
6. Arc faults are often sporadic and intermittent
7. The current waveform has strong randomness
The prevention and cure of electrical fires, which are the first in terms of fire hazards, are more important, and more attention is paid to preventing fires that have not been "burned". Arc-fault circuit breakers (AFDDs) were created to realize arc-protective switchgear that prevented electrical fires in the first place. AFDD - arc fault circuit breaker, also known as arc fault detection device, is a new type of protection appliance. It can detect arc faults in electrical lines, and can cut off the circuit before causing electrical fires, effectively preventing electrical fires caused by arc faults.
The difference between AFDD and traditional circuit breakers
traditional circuit breakers only protect against overcurrent and short circuit, while AFDD adds the function of protecting arc faults on this basis to prevent fires caused by arcs. It is a circuit protection device whose main function is to prevent fires caused by fault arcs. It has the ability to detect and distinguish between the normal arc and the fault arc generated when the electrical start-stop or switch is on, and cut off the power supply in time when the fault arc is found.
AFDD includes general structures such as operating mechanism, contact system, tripping mechanism, test button, wiring terminal, housing frame, etc. Its characteristic structure also includes arc detection circuit, arc fault electronic identification circuit (including microprocessor), which is based on PCB hardware And preset protection algorithm to realize intelligent arc detection and fault arc identification.