The technology of arc fault circuit breaker AFCI is a newest circuit protection technology, and its main function is to prevent fire caused by fault arcs. When the arc fault occurs, because the current intensity is small, it is lower than the set value of overcurrent protection which is widely installed in the power system especially in the field of low voltage distribution. The installation of the arc fault circuit breaker AFCI at the terminal of the distribution line is a measure to detect the arc and cut off the circuit in time and effectively reduce the loss of the arc.

Arc Fault Circuit Interrupter AFCI is an intelligent circuit protector, it can detect and identify the arcs and normal working arcs in the line. Prevention of hidden troubles caused by arc fault caused by poor contact and bad insulation in electrical circuit. Ensemble arc protection, overload protection, short circuit protection, over voltage protection and surge suppression.

Arc is a natural phenomenon that the insulator is broken through by voltage, and is transformed from non conductive to conductive and luminous. It is commonly called "arcing". Arcing fault is sudden, hidden and random. Fault arc is a common safety hazard in electrical circuits. Fault arcs occur in bad line insulation or bad contact. It may also occur at loose wire connections, as well as the connection between aging or damaged lines and electrical circuits. Fault arcs are generally divided into three kinds: series arc, parallel arc and ground arc. In electric short-circuit fire, the arc short circuit of grounding fault causes the greatest danger of fire, because the arc has a great impedance and voltage drop, it restricts the fault current, so that the overcurrent protection electric appliance can not move or can not act in time to cut off the power supply. The local high temperature of several ampere arcs can be as high as 3000~4000 degrees centigrade, enough to ignite the vicinity. The flammable material fires. Common circuit protection devices, such as leakage protector, overload protection device, circuit breaker and so on, can not effectively protect the fault arc.