Electric arc fault detector

Abstract

A device for detecting arc fault consists of current detector for detecting current variation and for generating its proportional signal, signal converter for limiting signal level, the first level limit amplifier, signal level detector for generating detection signal, pulse generator for forming normalization pulse, the first arc determining unit for counting pulse signal to judge whether arc is occurred or not and for generating arc detection signal, as well as breaker for cutting off wire when arc detection signal is generated.

Description

technical field [0001] The present invention relates to apparatus for detecting arc faults in power distribution systems, and in particular to an arc fault detection apparatus that separates harmful arcs that cause fires from voltages generated when starting electrical equipment and operating dimmers Effectively distinguish where these voltages are often mistaken for arcs. Background technique [0002] The causes of arc faults are various, for example, aging, breakage of insulation and conductors, mechanical and electrical stress caused by excessive use or excessive voltage, connection failures, and excessive mechanical failure of conductors. Generally, arc faults occurring in residential buildings or commercial buildings can be classified into three cases. [0003] First, a series arc (contact arc) occurs between wires connected in series with the load. Figure 1 shows the situation where series arcing occurs. Referring to FIG. 1 , the conductors 14 and 16 constituting th...

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Problems solved by technology

[0004] The second type, as shown in Figure 2, will cause a parallel arc between the wires (line arc)

Carbonization caused by excessive direct sunlight or lightning strikes affecting the wiring system, or cutting mechanical operations on the cable extension joint when the cable is crushed under furniture such as chairs, can cause aging or damage to the inner insulation

[0005] The third type, as shown in Figure 3, will cause a ground arc between the wire and the earth

Therefore, there is a problem with conventional arc fault detection equipment that it misinterprets the signal generated when operating the dimmer as an arc signal and cuts off the fixed circuit

Also, since the signal that occurs when operating a dimmer is very similar in magnitude to the arc signal, equipment that uses the magnitude of the conventional signal to detect arcs cannot distinguish a harmful arc from the signal that occurs when operating a dimmer

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