Method for detecting trouble electric arc and its protecting equipment

Abstract

The invention relates to detection of fault arc, wherein, fault arc cycle is recognized through at least two wave characters by gathering current waveform of each cycle; the fault arc is verified through judging whether a plurality of continuous fault arc cycles exist; if the waveform not only meets the condition that the amplitude is smaller than that of normal current or phenomenon of flat shoulder exists on a zero crossing point but also meets the condition that the waveform of positive and negative half cycles is asymmetric or di/dt is overlarge at a certain moment, then the cycle is estimated as a fault arc cycle; if a plurality of cycles continuously are estimated as fault arc cycle, then the fault arc is verified. Compared with the prior art, the technical proposal of the invention has the advantages that the fault arc can be detected during the process of normal power supply; the power can be automatically cut off within very short period, and simultaneously the fault arc current and the starting impulse current can be distinguished; the spurious trip rate is reduced.

Description

technical field [0001] The invention belongs to the field of circuit protection equipment, in particular to a method and a protection device for detecting fault arcs in a power distribution terminal system. Background technique [0002] Electrical lines and equipment in the house, such as: electrical wiring, sockets, wires inside household appliances or power lines of electrical appliances, etc., due to long-term overload operation, or poor electrical connections, etc., the insulation layer of the wires is aging , the insulation effect is reduced, or the insulation layer is damaged, a fault arc may occur. Arc sparks ignite the wiring and cause a fire. Currently commonly used circuit protection devices such as fuses and ground fault circuit interrupters cannot effectively detect fault arcs and form open circuit protection. AFCI (ArcFault Circuit Interrupter) technology is the latest circuit protection technology, which can provide arc fault protection. Its main function is ...

AI Technical Summary

Problems solved by technology

Most of the AFCI detection methods and protection circuits now identify the fault arc current by judging whether the derivative of the current waveform (di / dt, that is, the steepness of the waveform) exceeds the threshold value and whether the accumulated arc cycle exceeds the threshold value. However, the starting current and The fault arc current has the characteristics of steep waveform, so it is difficult for this AFCI detection method and protection circuit to distinguish the starting current and the fault arc current, and it is easy to cause identification errors and malfunctions

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