Arc monitoring device and control method therefor

Abstract

The present invention relates to an arc monitoring device comprising: a high frequency signal detection unit for detecting high frequency signals from an electric line; a blocking unit for blocking an electrical connection between a power source and a load; a voltage detection unit for detecting a voltage change in the electric line; a current detection unit for detecting a current change in the electric line; and a control unit. The control unit: detects ignition, which is a precursor to the occurrence of an arc, according to the difference between the average of accumulated magnitudes of high-frequency signals prior to a half-period of a current and the average of detected magnitudes of high-frequency signals during the half-period of the current; detects a current change according to the difference between a current amount detected during one period of the current and a current amount detected during one previous period of the current; estimates whether the arc occurs during a half period on the basis of the average of magnitudes of high frequency signals collected during the half period of the current when the ignition and the current change are detected; determines whether the arc occurs on the basis of whether the estimated number is equal to or greater than an allowable number; and blocks the electric line according to the determined result.

Description

Arc monitoring device and control method thereof

[0001] The present invention relates to an arc monitoring device for monitoring an arc and a control method of the device.

[0002] Arcing typically refers to an electrical spark or spark. It refers to a discharge phenomenon that occurs when a high potential difference occurs between positive and negative terminals, characterized by high current density. These arcs can be caused by damage to wires or electrical appliances, insulation breakdown, connection defects, or aging. They can also cause fires if there is flammable material nearby, making them a major cause of electrical fires.

[0003] Meanwhile, conventional leakage circuit breakers or overcurrent circuit breakers are basically designed to prevent leakage or short circuits, and their circuit breaker function can be activated when a current exceeding a preset size is detected for a certain period of time. However, arcs can occur even at low currents of 3 to 5 A or less, and it is difficult to detect arcs occurring at such low currents or arcs occurring for less than a certain period of time with leakage circuit breakers or overcurrent circuit breakers. Accordingly, various countries are mandating the installation of arc circuit breakers that can block such arcs, and research into detecting and blocking arcs is actively underway.

[0004] As part of this research, an arc detection device has been developed that detects noise in a current signal and detects the occurrence of an arc using the magnitude (or intensity, hereinafter referred to as magnitude) of a high-frequency component of the detected noise. However, in the case of current arc detection devices, the occurrence of an arc is determined only based on the magnitude of a specific high-frequency component detected from the current noise, and thus there is a limitation in distinguishing between general current noise and an arc. Accordingly, there is a problem that the precision of arc detection is not high, such as misidentifying noise as an arc or misjudging an arc as noise.

[0005] In order to increase the accuracy of such arc detection, methods have emerged that set a specific frequency band of interest for the noise generated when an arc occurs, and determine whether or not an arc occurs by determining whether noise occurs in the set frequency band of interest. However, this method has the problem that it is difficult to detect arc noise that occurs in an area outside the frequency band of interest. In addition, due to the technological development of current power conversion devices, arc noise has the characteristic of occurring in the form of white noise that occurs across a wide frequency band rather than a specific band of frequencies, and as described above, there is the problem that it is difficult to accurately detect an arc by monitoring in a specific frequency band of interest.

[0006] Moreover, in the case of a series arc that can occur when insulation damage occurs in either one of the live and neutral wires, the characteristics of the arc are more ambiguous than in a parallel arc in which insulation damage occurs in both the live and neutral wires, as the insulation in either wire is not damaged. Therefore, there is a problem in that detection of the series arc is more difficult than in a parallel arc.

[0007] The present invention aims to solve the above-mentioned problem and other problems, and to provide an arc monitoring device capable of detecting not only the magnitude of high-frequency noise capable of detecting an arc but also the variation of the high-frequency noise and the shoulder phenomenon caused by insulation damage by determining whether an arc has occurred in order to detect a series arc in which the characteristics of the arc appear more vaguely than in a parallel arc, and a method for controlling the arc monitoring device capable of detecting even insulation damage caused in one of the live and neutral wires.

[0008] In order to achieve the above or other purposes, according to one aspect of the present invention, an arc monitoring device according to an embodiment of the present invention includes a high-frequency signal detection unit for detecting a high-frequency signal from a current flowing in an electric circuit, a blocking unit for blocking the electric circuit to block the electrical connection between a power source and a load, a voltage detection unit for detecting a voltage change in the electric circuit, a current detection unit for detecting a current change in the electric circuit, and detecting ignition, which is a precursor phenomenon of arc occurrence, according to a difference between the average magnitude of a high-frequency signal accumulated before a half cycle of the current and the average magnitude of a high-frequency signal detected during a half cycle of the current, and detecting a current fluctuation according to a difference between the amount of current detected during one cycle of the current and the amount of current detected during one cycle of the current before a preset time, and when the ignition and current fluctuation are detected, estimating whether an arc has occurred during the half cycle based on the average magnitude of a high-frequency signal collected during the half cycle of the current, and determining whether an arc has occurred in the electric circuit based on whether the estimated number of arc occurrences is greater than or equal to a preset allowable number, and determining whether an arc has occurred in the electric circuit based on the determination result. It is characterized by including a control unit that controls the blocking unit to block the electric circuit.

[0009] In one embodiment, the control unit calculates a first current rms value, which is an rms value of current for one cycle of the current, and a second current rms value, which is an rms value of current for one cycle of the current prior to a preset time, and calculates a current fluctuation value based on a difference between the first and second current rms values, and detects that the current fluctuation has occurred when the calculated current fluctuation value is equal to or greater than a current fluctuation reference value determined based on the first current rms value.

[0010] In one embodiment, the control unit is characterized in that it accumulates the current fluctuation value when the current fluctuation value is less than the current fluctuation reference value, and detects that the current fluctuation has occurred when the accumulated current fluctuation value is greater than or equal to the current fluctuation reference value.

[0011] In one embodiment, the control unit is characterized in that it counts the number of times the current fluctuation value is calculated, compares a current fluctuation value size standard determined differently based on the counted number of times with the current fluctuation value, and accumulates the current fluctuation value to the previously accumulated current fluctuation value based on the comparison result.

[0012] In one embodiment, the control unit calculates a first average value which is an average value of high-frequency noise signal intensities detected during a half cycle of the current, calculates a second average value which is an accumulated average value of high-frequency noise signal intensities detected before a half cycle of the current, determines a first reference value and a second reference value according to a first ratio and a second ratio set in advance for the second average value, and detects whether the ignition has occurred based on a result of comparing the first average value with at least one of the first reference value and the second reference value, and is characterized in that the first ratio is a ratio greater than the second ratio.

[0013] In one embodiment, the control unit is characterized in that it detects that the ignition has occurred when the first average value is greater than or equal to the first reference value, or when the first average value is less than the first reference value but greater than or equal to the second reference value in a state where the current fluctuation is detected.

[0014] In one embodiment, the control unit is characterized in that, when the ignition and the current fluctuation are detected, the control unit further detects a zero section according to a time at which a current value within a critical range from a reference current is detected during a half cycle of the current, and an arc noise according to a fluctuation amount of a high-frequency signal, and when the zero section and the arc noise are further detected, the control unit estimates whether the arc occurs during the half cycle based on an intensity average of the high-frequency signal.

[0015] In one embodiment, the control unit estimates whether the zero section has occurred based on whether a preset number or more of samples having a voltage value within the threshold range are detected among current samples extracted during the half-cycle, and determines that the zero section has been detected when a zero count value obtained by accumulating the number of zero sections estimated for each half-cycle reaches a preset zero count reference value.

[0016] In one embodiment, the control unit is characterized in that, when the zero section is estimated, the control unit further performs a discrete Fourier transform to analyze the frequency components of the current values ​​detected during the half cycle of the current, and re-estimates the zero section according to the ratio of the fundamental wave and the harmonic wave detected as a result of the frequency component analysis.

[0017] In one embodiment, the control unit is characterized in that, if any one of the current fluctuation, the ignition, the zero section and the arc noise is not detected, the number of arc occurrences estimated up to now is initialized.

[0018] In one embodiment, the control unit is characterized in that it calculates the root mean square value of the current values ​​detected during the half cycle of the current, and initializes the number of arc occurrences estimated up to the present when the calculated root mean square value does not exceed a preset minimum value.

[0019] In one embodiment, the control unit determines the allowable number of times based on the calculated effective value, and the allowable number of times is determined to be smaller as the calculated effective value increases.

[0020] In one embodiment, the control unit determines whether the half-cycle of the current has entered an arc check period for detecting whether an arc has occurred within a threshold time determined by a preset number of half-cycles, and if the half-cycle of the current is not a half-cycle included in the arc check period, the control unit deducts the estimated number of arc occurrences estimated up to now.

[0021] In order to achieve the above or other purposes, according to one aspect of the present invention, a control method of an arc monitoring device according to an embodiment of the present invention comprises a first step of sampling a current signal and a high-frequency signal during a half cycle of a current flowing in a circuit, a second step of increasing an event time count for checking an elapsed time, a third step of detecting a current fluctuation according to a difference between the amount of current detected during one cycle of the current and the amount of current detected during one cycle of the current before a preset time, a fourth step of detecting ignition, which is a precursor phenomenon of arc occurrence, according to a difference between the average magnitude of a high-frequency signal accumulated before the half cycle of the current and the average magnitude of a high-frequency signal detected during the half cycle of the current, a fifth step of estimating whether an arc has occurred during the half cycle of the current based on the average intensity of the high-frequency signal when the current fluctuation and the ignition are detected, a sixth step of increasing the estimated number of arc occurrences when an arc occurrence is estimated and checking whether the number of arc occurrences accumulated up to the present is greater than or equal to a preset allowable number, and a sixth step of checking whether the number of arc occurrences accumulated up to the present is greater than or equal to the preset allowable number, and determining whether the number of arc occurrences is greater than or equal to the number of times the accumulated ... It is characterized by including a seventh step of cutting off the electrical connection between the power source and the load by cutting off the circuit when the number of accumulated arc occurrences is greater than the allowable number, and an eighth step of initializing the event time count depending on whether the accumulated event time count has reached a preset number of half-cycles corresponding to a preset threshold time when the number of accumulated arc occurrences is less than the allowable number.

[0022] In one embodiment, the third step is characterized by including a step 3-1 of calculating a first current rms value, which is a current rms value for one cycle of the current, a step 3-2 of calculating a second current rms value, which is a current rms value for one cycle of the current prior to a preset time, a step 3-4 of calculating a current fluctuation value based on a difference between the first and second current rms values, and a step 3-4 of detecting that the current fluctuation has occurred when the calculated current fluctuation value is equal to or greater than a current fluctuation reference value determined based on the first current rms value.

[0023] In one embodiment, the step 3-4 further includes a step a of accumulating the current fluctuation value when the current fluctuation value is less than the current fluctuation reference value, and a step b of detecting that the current fluctuation has occurred when the accumulated current fluctuation value is greater than or equal to the current fluctuation reference value, wherein the step b includes a step b-1 of differently determining a current fluctuation value size standard based on the number of times the current fluctuation value is calculated, and a step b-2 of accumulating the current fluctuation value to the previously accumulated current fluctuation value based on a result of comparing the current fluctuation value size standard determined in the step b-1 with the current fluctuation value.

[0024] In one embodiment, the fourth step includes a step 4-1 of calculating a first average value which is an average value of the high-frequency noise signal intensities detected during a half cycle of the current, and a second average value which is an accumulated average value of the high-frequency noise signal intensities detected before the half cycle of the current, a step 4-2 of determining a first reference value and a second reference value according to a first ratio and a second ratio set in advance for the second average value, and a step 4-3 of detecting whether the ignition has occurred based on a result of comparing the first average value with at least one of the first reference value and the second reference value, wherein the first ratio is a ratio greater than the second ratio.

[0025] In one embodiment, the fifth step is characterized by including a step 5-1 of detecting a zero section according to a time at which a current value within a threshold range from a reference current is detected during a half cycle of the current when the current fluctuation and the ignition are detected, a step 5-2 of further detecting arc noise according to the amount of fluctuation of a high-frequency signal, and a step 5-3 of estimating whether an arc occurs during a half cycle of the current based on an intensity average of the high-frequency signal when the zero section and the arc noise are further detected.

[0026] In one embodiment, the step 5-1 is characterized by including a step c of estimating whether the zero section has occurred based on whether a preset number or more of samples having a voltage value within the threshold range among current samples extracted during the half-cycle have been detected, and a step d of determining that the zero section has been detected when a zero count value, which is an accumulated value of the number of zero sections estimated for each half-cycle, reaches a preset zero count reference value.

[0027] In one embodiment, the step d is characterized by including a step d-1 of analyzing frequency components of current values ​​detected during a half cycle of the current by performing a discrete Fourier transform when the zero section is estimated, and a step d-2 of re-estimating the zero section according to the ratio of the fundamental wave and harmonic wave detected as a result of the frequency component analysis.

[0028] In one embodiment, the step 5-2 is characterized by including: a step e for calculating an average value and a maximum value of a high-frequency signal detected during a half cycle of the current; a step f for calculating a high-frequency signal fluctuation value during a half cycle and a high-frequency signal fluctuation value during one cycle by comparing the calculated average value and maximum value with the average value and the maximum value of a high-frequency signal detected during a half cycle prior to the half cycle of the current, and with the average value and the maximum value of a high-frequency signal detected during a half cycle prior to one cycle from the half cycle of the current; a step g for increasing an arc noise count by at least one to estimate whether arc noise has occurred based on a result of comparing the calculated high-frequency signal fluctuation value during a half cycle and the high-frequency signal fluctuation value during a one cycle with a preset high-frequency signal minimum value; and a step h for estimating that the arc noise has occurred when the increased arc noise count is equal to or greater than a preset arc noise reference value.

[0029] In one embodiment, the fifth step is characterized by further including a fifth-fourth step of initializing the number of arc occurrences estimated up to now if any one of the current fluctuation, the ignition, the zero section and the arc noise is not detected.

[0030] In one embodiment, the fifth step further includes a step 5-5 of calculating an rms value of current values ​​detected during a half cycle of the current, and a step 5-6 of initializing the number of arc occurrences estimated up to the present when the calculated rms value does not exceed a preset minimum value. The step 5-5 further includes a step i of determining the allowable number of occurrences based on the calculated rms value, and the allowable number of occurrences is determined to be smaller as the calculated rms value increases.

[0031] The effects of the arc monitoring device and the arc monitoring device control method according to the present invention are described as follows.

[0032] According to at least one of the embodiments of the present invention, the present invention has the effect of detecting an arc occurrence precursor phenomenon (ignition phenomenon) according to not only the magnitude of high-frequency noise but also the change in the magnitude of high-frequency noise caused by the amount of current fluctuation over a preset period of time and the insulation damage, thereby determining whether an arc has occurred, thereby detecting an arc caused by insulation damage of either a live line or a neutral line, i.e., a series arc. Accordingly, the present invention has the effect of preventing damage to a load and an internal power device due to the occurrence of the series arc.

[0033] Furthermore, the present invention can estimate whether an arc has occurred during each half-cycle of an alternating current whenever a current corresponding to that half-cycle flows, and determine that an arc has occurred when the estimated number of occurrences reaches a preset number. Accordingly, it has the effect of reducing the possibility of a malfunction in which noise with characteristics similar to those of an arc is temporarily mistaken for an arc and the circuit is mistakenly shut down.

[0034] Furthermore, the present invention determines at least one of the reference values ​​for estimating whether an arc has occurred based on the characteristics of the current flowing through the wire, thereby dynamically estimating whether an arc has occurred based on the characteristics of the current. This has the effect of enabling more accurate detection of whether an arc has occurred.

[0035] Figure 1 is a conceptual diagram to explain the types of arcs according to their cause of occurrence.

[0036] Figure 2 is an example diagram showing an example of arc noise appearing in a wide frequency band in the form of white noise.

[0037] FIG. 3 is a block diagram illustrating the configuration of an arc monitoring device according to an embodiment of the present invention.

[0038] Figure 4 is a diagram showing typical high-frequency arc noise and high-frequency noise and current and voltage changes when an arc occurs.

[0039] FIG. 5 is a flowchart illustrating an operation process for determining whether an arc has occurred in an arc monitoring device according to an embodiment of the present invention.

[0040] FIG. 6 is a flowchart illustrating another operation process for determining whether an arc has occurred in an arc monitoring device according to an embodiment of the present invention.

[0041] FIG. 7 is a flowchart illustrating an operation process for detecting a current fluctuation amount over a preset period of time in an arc monitoring device according to an embodiment of the present invention.

[0042] Figure 8 is a flowchart illustrating an operation process of accumulating a current fluctuation value calculated according to the size of the current fluctuation amount during the operation process of Figure 7.

[0043] FIG. 9 is a flowchart illustrating an operation process for detecting ignition, which is a precursor phenomenon of arc occurrence, in an arc monitoring device according to an embodiment of the present invention.

[0044] FIG. 10 is a flowchart illustrating an operation process for detecting whether a zero section has occurred during a half cycle of an alternating current in an arc monitoring device according to an embodiment of the present invention.

[0045] FIG. 11 is a flowchart illustrating an operation process for determining whether high-frequency noise fluctuates in an arc monitoring device according to an embodiment of the present invention.

[0046] FIG. 12 is a flowchart illustrating an operation process for determining whether high-frequency noise corresponding to arc occurrence is included in an arc monitoring device according to an embodiment of the present invention.

[0047] FIG. 13 is a flowchart illustrating an operation process of delaying the expiration of an event time for determining whether an arc has occurred when a preset condition is met in an arc monitoring device according to an embodiment of the present invention.

[0048] It should be noted that the technical terms used herein are used merely to describe specific embodiments and are not intended to limit the present invention. Furthermore, singular expressions used herein include plural expressions unless the context clearly dictates otherwise. The suffixes "module" and "part" used in the following description for components are assigned or used interchangeably solely for the convenience of writing the specification, and do not in themselves have distinct meanings or roles.

[0049] In this specification, the terms “comprises” or “includes” should not be construed to necessarily include all of the components or steps described in the specification, and some of the components or steps may not be included, or additional components or steps may be included.

[0050] In addition, when describing the technology disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the technology disclosed in this specification, the detailed description is omitted.

[0051] In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. In addition, not only each embodiment described below, but also a combination of embodiments may correspond to the spirit and technical scope of the present invention as modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0052] Figure 1 is a conceptual diagram to explain the types of arcs according to their cause of occurrence.

[0053] Referring to Fig. 1, Fig. 1 shows an example of an arc occurring in a single-phase circuit consisting of a live wire and a neutral wire. As described above, an arc is caused by insulation breakdown due to aging, deterioration, or physical damage, and can refer to a phenomenon in which an electrical discharge occurs between the two ends of a disconnected wire due to a gas acting as a conducting medium when at least a portion of the wire is disconnected. In other words, a state in which at least a portion of the wire is disconnected but current can flow due to an electrical discharge can be referred to as an 'arc'.

[0054] Even if only part of the circuit is disconnected, or even the entire circuit is disconnected, if current can be conducted through a gas, the electrical energy of the power source can be supplied to the load through the remaining portion or the gas that serves as the conducting medium. However, if current flows through the gas as the conducting medium, there is a risk of electrical fire because air discharge of electrical energy occurs in the surrounding area.

[0055] Meanwhile, such arcs may occur for individual reasons in each circuit. For example, in the case of a single-phase circuit consisting of a live line (L line) and a neutral line (N line) as shown in Fig. 1, arcs may occur in only one of the live lines and the neutral line as shown in Fig. 1 (a), or arcs may occur in all circuits, i.e., both the live line and the neutral line as shown in Fig. 1 (b).

[0056] For example, in cases such as aging or deterioration of a circuit, an arc may occur only in either the live wire or the neutral wire, as shown in (a) of Fig. 1. An arc occurring only in one circuit is referred to as a series arc hereinafter.

[0057] On the other hand, unlike the serial arc described above, as shown in (b) of Fig. 1, arcs can occur in both the live and neutral lines. For example, if strong physical pressure, such as from heavy equipment, is applied to both circuits, physical damage may occur to both circuits, and this physical damage may cause arcs to occur in both circuits. Hereinafter, an arc resulting from physical damage to both circuits will be referred to as a parallel arc.

[0058] Meanwhile, when such an arc occurs, electricity can be supplied to the load due to the discharge phenomenon that occurs between both ends of each disconnected circuit. Accordingly, when an arc occurs, the size of the arc changes around the ZCP (Zero Cross Point), which is a point with a reference voltage (e.g., 0 V) ​​as the polarity of the current switches. More specifically, the arc size increases as it moves away from the ZCP, and the arc size decreases as it moves closer to the ZCP, showing a cyclical characteristic.

[0059] Meanwhile, a noise signal including a typical noise, for example, switching noise (211), has the characteristic that its size decreases as the frequency increases, as shown in the noise signal (210) in FIG. 2. However, noise generated when an arc occurs has the characteristic of occurring in the form of white noise that occurs evenly throughout a wide frequency band ranging from tens of MHz to hundreds of MHz, as shown in the arc noise signal (200) in FIG. 2.

[0060] FIG. 3 is a block diagram illustrating the configuration of an arc monitoring device according to an embodiment of the present invention for monitoring an arc in the form of white noise that occurs in a wide frequency band ranging from several tens of MHz to several hundred MHz and has a periodic characteristic in which the arc changes around the ZCP (Zero Cross Point) as such. FIG. 4 is an exemplary diagram for explaining the periodic characteristics of a high-frequency noise signal that occurs when an arc occurs and the current change when an arc occurs.

[0061] First, referring to FIG. 3, the arc monitoring device according to an embodiment of the present invention may be configured to include a blocking unit (350), a current detection unit (310), a voltage detection unit (320), a high frequency current transformer (HFCT) (330), a filter unit (331), an amplifier unit (332), a control unit (300), a communication unit (360), a memory (370), and an output unit (380). In addition, the device may further include a zero-phase current transformer (ZCT) (340). The components illustrated in FIG. 3 are not essential for implementing the arc monitoring device, and thus, the arc monitoring device described in this specification may have more or fewer components than the components listed above. In addition, each component of the arc monitoring device illustrated in FIG. 3 may be connected to the control unit (300) and may be controlled by the control unit (300).

[0062] First, the blocking unit (350) can block the electrical connection between the power source and the load when it is determined that an arc has occurred or a leakage current is generated. The blocking unit (350) can include a trip coil and a driving circuit for driving the trip coil, and the driving circuit can be driven according to a trip control signal provided from the control unit (300). That is, the blocking unit (350) can be driven according to the trip control signal provided from the control unit (300) to perform a blocking operation for blocking the connection between the load and the power source.

[0063] The current detection unit (310) can detect the amount of current flowing in the electric circuit connecting the power source and the load. The current detection unit (310) may include a preset shunt resistor or a low frequency current transformer (LFCT) to detect the amount of current. In this case, the current detection unit (310) can detect the amount of current based on the voltage difference measured at both ends of the shunt resistor or the low frequency current signal detected by the LFCT. In addition, the current detection unit (310) may be equipped with an LPF (Low Pass Filter) to remove noise from the measurement result, and may further include an amplifier to amplify the measured value to a level that the control unit (300) can recognize.

[0064] Here, a bimetallic component used in an arc monitoring device according to an embodiment of the present invention may be used as the shunt resistor. In this case, the current detection unit (310) may detect the amount of current flowing in the circuit based on the specific resistance value of the bimetallic component. In this case, a separate shunt resistor may not be provided.

[0065] And the voltage detection unit (320) can detect the voltage change of the electric circuit. In this case, if the current flowing in the electric circuit is a single-phase current, the current flowing between the power line and the internal line may be an alternating current whose voltage phase periodically alternates according to the cycle of the single-phase current. Accordingly, in the electric circuit, positive (+) voltage and negative (-) voltage may periodically alternate around the ZCP. Therefore, the control unit (300) can detect the ZCP based on the voltage change of the electric circuit.

[0066] Meanwhile, the HFCT (330) can detect a high-frequency noise signal having a frequency higher than a certain frequency, i.e., a high-frequency noise signal, from the current flowing in the circuit. To this end, the HFCT (330) can be formed so that any one of the circuits passes through it. In addition, the HFCT (330) can include at least one sensor that detects a wide high-frequency noise signal ranging from several tens of MHz to several hundred MHz that is generated when a partial discharge or an arc occurs. Preferably, the HFCT (330) can detect a high-frequency noise signal ranging from 10 MHz to 150 MHz or from 10 MHz to 200 MHz.

[0067] In addition, the filter unit (331) is a HPF (High Pass Filter) formed to pass only high-frequency signals, and may be a filter that passes only signals in a high-frequency band ranging from tens of MHz to hundreds of MHz. In addition, the filter unit (331) may further include a filter that filters a specific frequency in a frequency mask manner. Here, the specific frequency may be a frequency corresponding to living noise, noise generated when driving a load, or electromagnetic noise (EMC (ElectroMagnetic Compatibility) Noise). That is, the filter unit (331) may be a filter that passes signals in a high-frequency band, and may be a filter that filters signals in at least one specific frequency band that is designated in advance so as not to pass. Through this, not only signals in a low-frequency band, but also noise whose frequency band is known in advance, such as living noise, driving noise of a load, electromagnetic noise, etc., can be removed.

[0068] And the amplifier (332) can receive the filtered high-frequency noise signal and amplify the received signal into a signal of a level identifiable by the control unit (300). The amplifier (332) can include an analog-to-digital converter (ADC) for converting the high-frequency noise signal in an analog form into a digital signal. In addition, the amplifier (332) can be a logarithmic amplifier whose input / output voltage ratio exhibits a logarithmic characteristic, which can indicate a wide input voltage range.

[0069] And the control unit (300) controls each component of the arc monitoring device and can control the overall operation of the arc monitoring device.

[0070] The control unit (300) can receive a high-frequency noise signal amplified through the amplifier unit (332). And, it can detect changes in the intensity of the high-frequency noise signal and changes in the current size over a certain period of time (e.g., half a cycle of a single-phase current).

[0071] Here, arcing can refer to a voltage discharge that occurs due to a voltage change caused by a short circuit in at least a portion of a wire, as described above. In this case, when the voltage discharge occurs, current flows through a gas, increasing the current. However, since this current flow through a gas is significantly affected by the surrounding environment, a significant deviation in the current amount can occur when an arc occurs.

[0072] Therefore, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can compare the amount of current detected during a certain period of time with the amount of current detected before the certain period of time to calculate a change value of the amount of current, and determine whether a phenomenon related to arc generation occurred during the certain period of time based on the calculated change value.

[0073] In addition, as described above, an arc is generated by a short circuit in at least a portion of a wire caused by insulation breakdown, and even if an arc has not yet occurred, the size of a high-frequency noise signal may increase by a certain level or more compared to a size that normally occurs due to the insulation breakdown. In other words, an increase in the size of a high-frequency noise signal by a certain level or more may be a phenomenon in which an arc is expected to occur. Accordingly, when an increase in the size of the high-frequency signal is detected, the control unit (300) can determine that this is a phenomenon related to the occurrence of an arc. Hereinafter, the phenomenon in which the size of the high-frequency noise signal increases by a certain level or more will be referred to as ignition.

[0074] The above current fluctuation and ignition may be a phenomenon detected before an arc has occurred. In other words, it may be a precursor phenomenon to an arc occurrence.

[0075] Accordingly, the control unit (300) can estimate whether high-frequency noise corresponding to arc occurrence has occurred based on a reference value determined according to the current level when the precursor phenomenon of the arc occurrence, i.e., the change in the current amount and the ignition are detected. In addition, if it is estimated that high-frequency noise corresponding to the arc occurrence has occurred more than a preset number of times during a preset time (estimation of arc occurrence), it can be determined that an arc has occurred.

[0076] Alternatively, in order to make a more accurate judgment, in addition to the aforementioned precursor phenomenon of the arc, if other phenomena that can be detected when an actual arc occurs are detected, the control unit (300) can estimate whether high-frequency noise corresponding to the arc occurrence occurs based on a reference value according to the currently detected current amount.

[0077] As described above, since an arc is energized by a voltage discharge that occurs according to a change in voltage when at least a portion of a wire is disconnected, a section in which the amount of current is within a critical range from a reference current (e.g., 0 A), i.e., a zero section, may occur until the voltage difference between the disconnected ends reaches a certain level. Accordingly, when the zero section is detected, the control unit (300) may determine that a phenomenon related to arc generation has occurred.

[0078] In addition, since an arc is accompanied by a high-frequency noise signal as described above, when an arc occurs, the average and maximum values ​​of the high-frequency noise signal may increase above a certain level. Accordingly, when a fluctuation in the high-frequency noise signal above a certain level occurs, the control unit (300) may determine that a phenomenon related to arc occurrence has occurred.

[0079] And in the state where the precursor phenomenon of the arc occurrence, that is, the fluctuation of the current amount and the ignition are detected, if both the zero section and the fluctuation of the high-frequency noise signal above a certain level are detected, it is possible to estimate whether high-frequency noise corresponding to the arc occurrence has occurred based on a reference value according to the currently detected current amount. And if it is estimated that the high-frequency noise corresponding to the arc occurrence has occurred more than a preset number of times during a preset time, it can be determined that the arc has occurred.

[0080] Meanwhile, the control unit (300) can acquire samples of a current signal (hereinafter, current samples) and samples of a high-frequency noise signal (hereinafter, high-frequency noise samples) in units of time corresponding to a half-cycle of the single-phase current. To acquire current samples and high-frequency noise samples during this half-cycle, the control unit (300) can detect a zero crossing point (ZCP) based on a voltage change of the circuit detected through the voltage detection unit (320). And, the time between zero crossing points can be detected as a half-cycle of the single-phase current.

[0081] Fig. 4 (a) is an exemplary diagram showing the characteristics of high-frequency arc noise, and Fig. 4 (b) is a diagram showing the current change of the arc according to the periodic pattern of the single-phase current. And Fig. 4 (c) is a diagram showing the voltage change of the arc according to the periodic pattern of the single-phase current. Here, Fig. 4 (c) shows the point where the voltage polarity switches according to the voltage change of the single-phase current that periodically crosses positive (+) and negative (-), i.e., the zero crossing point.

[0082] Referring to (a) of Fig. 4, when approaching the zero crossing point, the voltage difference between adjacent arc contacts may decrease. And when reaching ZCP, arcing may not occur. In this way, in the stage where arcing does not occur between arc contacts, i.e., the no-arc stage (411), high-frequency noise signals may be hardly detected because arcing does not occur.

[0083] However, depending on the characteristics of the single-phase current, i.e., the alternating current, the supplied voltage may gradually increase as it passes the zero-crossing point. Then, the voltage difference between the arc contacts may gradually increase. And when the voltage difference between the arc contacts exceeds a certain level, a discharge due to the accumulated voltage difference, i.e., an arc may occur. Therefore, as it passes the no-arc stage (411) corresponding to the zero-crossing point, the intensity and size of the high-frequency noise signal may increase as the arc is generated due to the increase in the voltage difference. In this way, as the voltage difference between the arc contacts increases, a stage in which the intensity of the high-frequency noise signal increases, i.e., the arc strike stage (412), may proceed.

[0084] Meanwhile, if the voltage difference between the arc contacts further increases and reaches a voltage that allows current to flow through the gas, i.e., a discharge, a discharge phenomenon may occur. Then, current may flow between the arc contacts on both sides of the shorted circuit due to the discharge phenomenon. In this case, as the current flows, the intensity of the high-frequency noise signal may decrease, and the current may increase. In this way, when the voltage difference between the contacts reaches a certain level, the arc conduction stage (413) may proceed, in which current flows through the gas, thereby reducing the high-frequency noise signal.

[0085] In the arc conduction phase (413), if the voltage decreases again according to the voltage change pattern of the AC current, a voltage sufficient to establish current flow between the two arc contacts may not be formed. Then, as current flow is interrupted, the current flowing between the arc contacts may discharge into the air. Accordingly, the arc quenching phase (414) may proceed, in which the intensity of the high-frequency noise signal increases again.

[0086] Meanwhile, in the arc quenching stage (414), the voltage may be further reduced according to the voltage change pattern of the alternating current. Then, the reduced voltage may again approach the zero crossing point, and in this case, the voltage difference between the contacts may again approach zero. Then, the no-arc stage (421) in which no arc occurs may proceed again.

[0087] Meanwhile, the control unit (300) may initiate sampling of current and high-frequency noise signals based on the detection result of the voltage detection unit (320). When the zero-crossing point is detected, sampling of current and high-frequency noise signals may begin until the next zero-crossing point is detected. The current and high-frequency noise signals sampled in this manner may be the current amount and high-frequency noise signals for the half-cycle.

[0088] Then, when the precursor phenomenon of the arc occurrence, i.e., the fluctuation of the current amount and the ignition are detected, the control unit (300) can estimate whether high-frequency noise corresponding to the arc occurrence occurs during the half cycle (hereinafter, the current half cycle) in which the current current sample and the high-frequency noise sample are acquired based on the reference value according to the currently detected current amount.

[0089] Alternatively, if the control unit (300) further detects the occurrence of a variation in the zero section and a variation in the high-frequency noise signal above a certain level while both the variation in the current amount and the ignition are detected, the control unit can estimate whether or not the high-frequency noise corresponding to the arc occurrence has occurred during the current half cycle based on a reference value according to the currently detected current amount.

[0090] And, if the control unit (300) estimates that high-frequency noise corresponding to the arc occurrence has occurred during the current half-cycle based on the reference value according to the currently detected current amount, it can determine whether the half-cycle in which the high-frequency noise corresponding to the arc occurrence has occurred has been detected a preset number of times or more during a preset time.

[0091] And, as a result of the judgment, if the half-cycle in which the high-frequency noise corresponding to the arc occurrence is estimated to have occurred is detected more than the preset number of times during the preset time, the control unit (300) can determine that an arc, for example, a serial arc, has occurred in the circuit.

[0092] Then, the control unit (300) can output a trip control signal to the blocking unit (350) to drive the blocking unit (350) and block the power supply to the load.

[0093] Here, the control unit (300) can perform a root mean square (RMS) calculation on the current samples acquired during the current half-cycle to calculate the current amount during the current half-cycle. And, based on the calculated current amount, at least one of the reference values ​​for arc detection can be determined.

[0094] For example, the control unit (300) may vary the preset reference number of times for determining whether an arc has occurred based on the estimated number of times the arc has occurred, depending on the magnitude of the current flowing through the circuit. In this case, the amount of current flowing through the circuit may be the amount of current during the half cycle.

[0095] Furthermore, in the case of serial arcs, the magnitude and characteristics of the high-frequency noise generated during arcing are ambiguous, making it difficult to distinguish from normal noise. Consequently, if a trip signal is output due to a presumed arc occurrence, the power supply to the load may be unnecessarily cut off.

[0096] In order to solve this problem, the present invention, when an arc occurrence is estimated as a result of detection by an arc monitoring device, it is primarily regarded as noise and allowed to occur a certain number of times, and only when the arc occurrence is estimated to occur more than the certain number of times can it be determined that an arc has occurred. In this case, since a serial arc occurs continuously and periodically, the serial arc can be distinguished from randomly occurring noise in that it occurs more than the certain number of times. Here, the certain number of times is an allowable number of times even if an arc is estimated to have occurred, and will be referred to as an allowable number of times hereinafter.

[0097] Meanwhile, the greater the current during the half cycle, the greater the impact on the arc may be. For example, the greater the calculated current, the greater the amount of electricity discharged by the arc. Accordingly, the risk of fire may increase. Accordingly, the control unit (300) may set the allowable number of times to be smaller as the current during the half cycle, i.e., the root mean square (RMS) value of the current during the half cycle, is larger, thereby ensuring that the electrical connection between the load and the power source is cut off even when the estimated number of arc occurrences is small.

[0098] On the other hand, if the root mean square value of the current during the half cycle is small, the effect on the arc may be small. For example, the smaller the calculated current, the less electricity may be discharged by the arc. Accordingly, the risk of fire, etc. may be lower. However, if the power between the load and the power source is cut off, the load cannot receive electrical energy, which may cause unexpected damage to the user. Accordingly, the smaller the root mean square value of the current during the half cycle, the more accurately it is possible to determine whether an arc has occurred, and the greater the allowable number of times can be set so that the electrical connection between the load and the power source is cut off only when the occurrence of an arc is confirmed. This allowable number of times may also be referred to as a time delay.

[0099] Meanwhile, the above allowable number of times can be set differently for each section depending on the effective current value during the half cycle.

[0100] For example, if the current effective value during the above half cycle is 20A or more, the above allowable number of times may be set to 2. In this case, an arc may be determined to have occurred only when it is estimated that an arc has occurred more than 2 times.

[0101] On the other hand, if the current effective value during the above half cycle is between 2.5A and 1A, the allowable number of times may be set to 18. Also, if the current effective value during the above half cycle is less than 1A, the allowable number of times may be set to 20. In this case, even if it is presumed that an arc has occurred when an arc-like phenomenon is detected, it may be determined that an arc has occurred only when it is presumed that an arc has occurred more than 18 and 20 times, respectively.

[0102] Meanwhile, the memory (370) can store a program for the operation of the control unit (300) and can store data input or output for performing the function of the arc monitoring device. For example, the memory (370) can store information on ZCP detected according to the voltage change detected by the voltage detection unit (320), and can store information on the current signal sampled by the current detection unit (310) and the high-frequency noise signal sampled by the HFCT (330). In addition, the memory can store information on various statistical values ​​calculated in relation to the current amount and the high-frequency noise signal during the half-cycle, such as the root-mean-square current (or half-cycle current RMS) calculated from the samples acquired between ZCPs, that is, during the half-cycle, and the average value or maximum value of the high-frequency noise signal during the half-cycle.

[0103] In addition, the communication unit (360) can perform a wired or wireless communication connection with a preset external server or a preset terminal. The communication unit (360) can provide measured information to the external server or the preset external terminal through the wired or wireless communication connection. Here, the external server may be a management server that manages the arc monitoring device according to an embodiment of the present invention, and the external terminal may be a preset user's terminal. In this case, the user's terminal may be a mobile terminal, a smart phone, a tablet PC, a laptop, or a other portable terminal. Alternatively, the external terminal may be a wearable device that the user can wear, such as a smart watch or smart glasses. Alternatively, the external terminal may be a fixed terminal, such as a PC.

[0104] Meanwhile, the arc monitoring device according to an embodiment of the present invention may further include a discrete Fourier transform (DFT) unit (not shown) for discrete Fourier transform (DFT) operation. The discrete Fourier transform unit may perform discrete Fourier transform on current samples acquired during the half cycle under the control of the control unit (300) to analyze frequency components of current detected during the half cycle. In addition, the control unit (300) may detect fundamental components and harmonic components from the current detected during the half cycle based on the discrete Fourier transform result, and calculate the ratio of the harmonic components to the fundamental component, i.e., the harmonic ratio.

[0105] In addition, the arc monitoring device may further include an output unit (380) for indicating the operating status of the arc monitoring device. The output unit (380) may include at least one of a light output unit and an audio signal output unit. The light output unit may include at least one LED capable of emitting light of different colors. In addition, the audio output unit may include at least one speaker or buzzer capable of outputting an audio signal. In the case of the light output unit, the operating status of the arc monitoring device may be indicated using light emitted from an LED or the like. In addition, in the case of the audio output unit, the operating status of the arc monitoring device may be indicated using an audio signal output from a speaker or the like.

[0106] In addition, the arc monitoring device may further include a ZCT (Zero-phase Current Transformer) (340) for detecting leakage current of the circuit. The ZCT can compare the magnitude of the current flowing from the power source to the load through the live line (L line) with the magnitude of the current flowing from the load to the power source through the neutral line (N line), and determine whether there is leakage current based on the difference. The ZCT (340) may be equipped with an LPF (Low Pass Filter) for filtering current noise. In this case, the arc monitoring device can detect whether a leakage current occurs based on the detection result of the ZCT (340). In addition, when a leakage current occurs, the circuit breaker (350) can be controlled to output a trip control signal and perform a circuit breaker operation.

[0107] Here, the above leakage current may be caused by an insulation breakdown at the ground. In this case, since the insulation breakdown means the occurrence of an arc, the above leakage current may correspond to an arc occurring at the ground, i.e., the occurrence of a ground arc. Therefore, the detection of the leakage current is to detect the occurrence of the ground arc, and accordingly, the arc monitoring device may determine whether a ground arc has occurred and, based on the determination result, may cut off the electrical connection between the power source and the load.

[0108] Meanwhile, the ZCT (340) may be an example of a leakage current detection unit for detecting leakage current. That is, it goes without saying that the present invention is not limited to having the ZCT (340) for leakage current detection. In the arc monitoring device according to an embodiment of the present invention, any other leakage current detection unit capable of detecting leakage current may replace the ZCT (340).

[0109] In the above description, each component constituting the arc monitoring device according to an embodiment of the present invention has been described in detail. In the following description, the operation process for detecting a serial arc in the arc monitoring device including the above-described components will be examined in detail with reference to multiple flowcharts.

[0110] First, FIG. 5 is a flowchart illustrating an operation process for determining whether an arc has occurred in an arc monitoring device according to an embodiment of the present invention.

[0111] First, FIG. 5 is a flowchart illustrating an operation process for determining whether an arc has occurred in an arc monitoring device according to an embodiment of the present invention.

[0112] Referring to FIG. 5, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can first detect a half-cycle of a single-phase current (S500). In this case, the start and end of the half-cycle can be detected according to ZCP. Here, ZCP is the point in time when the voltage polarity switches, i.e., the point in time when the voltage reaches 0 V, and can be detected according to the detection result of the voltage detection unit (320).

[0113] When a ZCP is detected, the control unit (300) can start sampling the current signal and the high-frequency noise signal until the next ZCP is detected. Since the ZCP occurs periodically every half cycle according to the voltage change pattern of the AC current, the current signal and the high-frequency noise signal sampled from the ZCP until the next ZCP is reached may be the current signal and the high-frequency noise signal sampled during the half cycle of the AC current. That is, by sampling the current signal and the high-frequency noise signal according to a preset sampling interval for every half cycle of the AC current signal based on the ZCP, the control unit (300) can obtain the current signal and the high-frequency noise signal during the half cycle. Hereinafter, the process of obtaining the current signal and the high-frequency noise signal during the half cycle will be referred to as a process of detecting the half-cycle current.

[0114] In order to detect the above-described semi-period current, the control unit (300) can receive the ZCP detected according to the voltage change of the voltage detection unit (320) as an interrupt signal. Then, sampling of the current signal and the high-frequency noise signal can be started depending on whether the interrupt signal is received. The sampling can continue until the next interrupt signal is received, i.e., until the next ZCP is received, and sampling can be restarted when the next interrupt signal is received.

[0115] Therefore, each time a half-cycle of a current signal elapses, current signals and high-frequency noise signals sampled during each half-cycle can be collected. Fig. 5 may be an operation process that is performed when current signal samples (hereinafter, current samples) and high-frequency noise signal samples (hereinafter, high-frequency noise samples) are collected during a half-cycle in this manner.

[0116] In addition, the S500 step may be a step in which an event time count is cumulatively increased at the same time as the semi-cycle current is detected. The event time count is for detecting the number of semi-cycles in which a current signal and a high-frequency noise signal are detected, and is for checking the passage of time. In addition, the event time count is for initializing at least one parameter for arc detection at a preset time cycle, and can prevent the current occurrence of an arc from being determined based on a result estimated a certain amount of time ago.

[0117] When the detection of the half-cycle current and the value of the event time count are increased in the above step S500, the control unit (300) can calculate the root mean square (RMS) value for each current value during the half-cycle in which the current current samples and high-frequency noise samples were acquired. In addition, when a phenomenon that can be mistaken for an arc occurring in the circuit (arc-like phenomenon) occurs, the allowable number of times (or delay time (Time delay)) for allowing this to be regarded as noise can be determined (S501).

[0118] As described above, the greater the current during the half cycle, the greater the impact on the arc may be. On the other hand, if the current during the half cycle is small, the impact on the arc may be small. Accordingly, the greater the current during the half cycle, the smaller the allowable number of times the control unit (300) can set to determine whether an arc has occurred more quickly. On the other hand, the smaller the current during the half cycle, the larger the allowable number of times the control unit (300) can set to determine whether an arc has occurred more accurately.

[0119] When the current amount according to the current samples during the above half cycle, i.e., the effective value, is calculated and the allowable number of times is determined, the control unit (300) can determine whether an arc precursor phenomenon, i.e., a current amount fluctuation which is the difference between the current amount detected during the half cycle and the current amount detected a certain time ago, has been detected and whether an ignition in which the size of a high-frequency noise signal increases above a certain level has been detected (S502).

[0120] Referring to FIGS. 7 to 9 below, the operation process for determining whether the current amount fluctuation and ignition are detected in the half cycle in which the current current sample is acquired will be examined in more detail.

[0121] In the above step S502, if the current amount fluctuation and ignition are not detected in the current half-cycle, the control unit (300) can initialize the arc check count calculated up to the present (S503). Then, the process proceeds to step S500 again to acquire current samples and high-frequency noise samples for a new half-cycle. In this case, the event time count can be increased.

[0122] On the other hand, in step S502, if the current amount fluctuation and ignition are detected in the current half cycle, the control unit (300) can compare the current root mean square value during the current half cycle with the preset current minimum value (S504). In addition, if the current root mean square value during the current half cycle is lower than or equal to the current minimum value, the control unit can proceed to step S503 to initialize the arc check count. This is because, if the current root mean square value during the current half cycle is lower than or equal to the current minimum value, the resulting arc can also be so small that it can be ignored.

[0123] However, if the comparison result of the step S504 shows that the current effective value during the current half cycle exceeds the preset minimum current value, the control unit (300) can determine whether the arc check cycle has been entered by comparing the event time count accumulated up to now with the preset threshold time (S506). In this case, the threshold time can be set to the number of half cycles of the AC current. Therefore, the control unit (300) can determine whether the arc check cycle has been entered by comparing the accumulated event time count with the number of half cycles corresponding to the threshold time.

[0124] Here, the above arc check cycle refers to a cycle in which whether an arc occurs is checked, and may refer to a time in which, within a preset time, whether an arc occurs is determined (arc check) through the current effective value during the half cycle.

[0125] For example, the control unit (300) can detect a current signal and a high-frequency noise signal for each half-cycle based on a half-cycle (sample the current signal and the high-frequency noise signal based on a half-cycle), and check whether an arc occurs at a preset time interval. Here, the preset time is a time corresponding to when a preset number of half-cycles of the AC current have elapsed, and it can be determined whether the preset time has elapsed based on the number of half-cycles in which current samples and high-frequency noise samples have been detected.

[0126] For example, the preset time may be a time corresponding to 30 cycles of an alternating current. In this case, the control unit (300) may determine that the preset time has elapsed when the number of half cycles in which current samples and high-frequency noise samples are detected reaches 60.

[0127] In this case, the control unit (300) can enter the arc check period after a certain period of time has elapsed since the event time count has been initialized. To this end, the control unit (300) can compare the accumulated event time count with a preset threshold time (the number of half-cycles corresponding to the threshold time), and can determine that the arc check period has been entered if the event time count is greater than or equal to the threshold time. That is, when the threshold time is 0, the control unit (300) can enter the arc check period immediately after the event time count has been initialized. On the other hand, when the threshold time is 10, the control unit (300) can enter the arc check period after current samples and high-frequency noise samples for 9 half-cycles have been detected.

[0128] If the judgment result of the step S506 above is that the arc check period has not been entered, that is, if the threshold time has not elapsed since the event time count was initialized, the control unit (300) can deduct the arc check count accumulated up to now (S507). In this case, if the arc check count accumulated up to now is the minimum value (e.g., the initial value, 0), the control unit (300) can maintain the minimum value of the arc check count. Then, the process proceeds to step S500 again to acquire current samples and high-frequency noise samples for a new half-cycle. In this case, the event time count can be increased.

[0129] On the other hand, if the judgment result of the above step S506 is that the arc check cycle has been entered, the control unit (300) can determine whether high-frequency noise corresponding to arc occurrence is included within the current half cycle based on the preset arc check level (S508).

[0130] Here, the arc check level may be determined based on the root mean square (RMS) current during the current half cycle. For example, if the root mean square (RMS) current during the current half cycle is 20 A or more, the arc check level may be set to 5. On the other hand, if the root mean square (RMS) current during the current half cycle is less than 2.5 A, the arc check level may be set to 20.

[0131] That is, the larger the current amount (rms value) during the current half cycle, the faster arc detection is required, and thus the arc check level can be set lower. On the other hand, the smaller the current amount (rms value) during the current half cycle, the more accurate detection is required rather than rapid detection, and thus the arc check level can be set higher.

[0132] Meanwhile, within the current half-cycle, whether high-frequency noise corresponding to arc occurrence is included based on a preset arc check level can be determined based on whether the average value of high-frequency noise during the current half-cycle exceeds the high-frequency noise value according to the arc check level, and whether the average value of high-frequency noise during each half-cycle accumulated up to now exceeds the high-frequency noise value according to the accumulated arc check level determined according to the arc check level.

[0133] In this way, the operation process of determining whether high-frequency noise corresponding to arc occurrence is included based on the arc check level according to the high-frequency noise average value and the accumulated high-frequency noise average value during the current half cycle will be examined in more detail with reference to FIG. 12.

[0134] Meanwhile, if it is determined that high-frequency noise corresponding to arc occurrence is included as a result of the determination in step S508, the control unit (300) may increase the arc check count (S510). Accordingly, if there is an arc check count accumulated up to now, the accumulated value of the arc check count may be increased.

[0135] Then, the control unit (300) can compare the accumulated value of the arc check count with the allowable number of times determined in step S501 (S512).

[0136] And if the arc check count is greater than the allowable number of times as a result of the comparison in step S512, the control unit (300) can determine that an arc has occurred. Accordingly, a trip control signal can be transmitted to the cutoff unit (350) to cut off the load from the power source (S513). Then, according to the operation of the cutoff unit (350), the circuit between the power source and the load is opened, so that the power supply to the load can be cut off.

[0137] On the other hand, if the arc check count as a result of the comparison in step S512 is less than the allowable number, the control unit (300) can check whether the event time count has reached the preset reference time count (S514).

[0138] And if, as a result of the check in step S514, the arc check time count accumulated up to now has not reached the reference time count, the control unit (300) can proceed to step S500 again to acquire current samples and high-frequency noise samples for a new half-cycle. Then, the event time count is increased and the processes below step S500 can be performed again.

[0139] On the other hand, if the result of the check in step S514 indicates that the event time count increased to date has reached the preset reference time count, the control unit (300) can initialize the event time count counted to date (S516). For example, if the reference time count is set to 60, the event time count can be initialized to 0 through steps S512 and S514 when the event time count accumulated to date reaches 60.

[0140] And the control unit (300) can reset the arc check counts checked before the reference time count among the arc check counts checked up to now (S518). Accordingly, the arc check counts counted before the reference time count (e.g., 60) among the arc check counts counted up to now can be initialized. Accordingly, the number of arc check counts counted up to now can be reduced.

[0141] For example, if the arc check count is counted when the event time count is 50, the event time count may be reset to 0 again when the event time count reaches 60. However, the arc check count may remain counted as 1.

[0142] And when the arc check count is counted when the event time count becomes 20 again, the arc check count can be increased to 2. Also, when the arc check count is counted when the event time count is 59, the arc check count can be increased to 3. In this state, when the event time count becomes 60 again, the event time count can be reset to 0 again.

[0143] However, in this case, among the arc check counts counted so far, the first counted arc check count may be the arc check count counted before 60 event time counts (reference time count) from the time when the event time count was initialized to 0.

[0144] In the above example, the first arc check count may be an arc count counted before the time corresponding to the event time count of 70. Therefore, in step S518, the control unit (300) may initialize an arc check count that occurred before the reference time count among the arc check counts counted up to now. That is, as the first arc check count is initialized, the arc check count may be reduced from 3 to 2.

[0145] Then, the control unit (300) can proceed to step S500 again in a state where the arc check count counted before the reference time count is initialized, and acquire current samples and high-frequency noise samples for a new half-cycle. In this case, the event time count can be increased. And the processes below step S500 can be performed again.

[0146] To this end, the control unit (300) may store information on the event time count corresponding to the counted arc check count in the memory (370) each time the arc check count is counted. Then, based on the information on the event time count corresponding to each arc check count stored in the memory (370), the arc check count count counted before the reference time count may be deducted from the accumulated arc check count. Then, the process may proceed to step S500 again to acquire current samples and high-frequency noise samples for a new half-cycle. In this case, the event time count may be increased. Then, the processes below step S500 may be performed again.

[0147] Meanwhile, according to the above-described description, the arc monitoring device according to the embodiment of the present invention can not only detect precursor phenomena of arc occurrence, i.e., current fluctuation and ignition, but also determine whether high-frequency noise corresponding to arc occurrence occurs only when phenomena accompanying arc occurrence, i.e., zero section and increase in the size of high-frequency noise signal above a certain level, are detected.

[0148] FIG. 6 is a flowchart illustrating an operation process for determining whether an arc has occurred only when both the precursor phenomenon of an arc occurrence and the accompanying phenomenon when an arc has occurred are detected in an arc monitoring device according to an embodiment of the present invention.

[0149] Referring to Fig. 6, steps S500 to S502 may be performed in the same manner as in Fig. 5. In addition, in step S502, if a precursor phenomenon of arc occurrence, i.e., a change in current amount and ignition, is detected as a result of detecting the change in current amount and ignition, the control unit (300) may further detect whether a zero section has occurred during the half cycle (hereinafter, referred to as the current half cycle) in which the current sample and the high-frequency noise sample were collected, in which a current having a value corresponding to the reference current, for example, a value within a preset threshold range from the reference current, has lasted for a preset time or longer. In addition, based on the amount of change in the average value and the maximum value of the high-frequency noise signal, it may further detect whether high-frequency noise accompanying arc occurrence, i.e., arc noise, has occurred during the current half cycle (S600).

[0150] With reference to FIGS. 7 to 9 below, the operation process for determining whether an arc occurrence precursor phenomenon, i.e., a change in current amount and ignition, has been detected will be examined in more detail.

[0151] If the detection result of the above step S600 indicates that the occurrence of the zero section and arc noise fluctuation is not detected, the control unit (300) may proceed to step S503 in the same manner as when the current fluctuation and ignition of step S502 are not detected, and initialize the arc check count accumulated up to the present. Then, the control unit may proceed to step S500 again and perform the subsequent operation processes.

[0152] On the other hand, if the detection result of the step S600 detects the occurrence of the zero section and arc noise fluctuation, the control unit (300) may proceed to step S504 to compare the current effective value during the current half cycle with the preset minimum current value (S504). If the comparison result of the step S504 shows that the current effective value during the current half cycle is less than or equal to the minimum current value, the control unit (300) may proceed to step S503 to initialize the arc check count. Then, the control unit may proceed to step S500 again to perform the subsequent operation processes.

[0153] On the other hand, if the comparison result of step S504 indicates that the current effective value during the current half-cycle exceeds the current minimum value, the control unit (300) can proceed to compare the event time count accumulated up to the present with the preset threshold time. Then, the operation of step S506 for determining whether the arc check cycle has been entered can be performed. Then, the operation processes after step S506 described in FIG. 5 can be performed.

[0154] Meanwhile, as described above, the control unit (300) of the arc monitoring device according to the embodiment of the present invention compares the amount of current detected during a certain period of time with the amount of current detected before the certain period of time in step S502 of FIGS. 5 and 6 to determine whether the amount of current has changed.

[0155] FIG. 7 is a flowchart illustrating an operation process for detecting the current fluctuation amount in an arc monitoring device according to an embodiment of the present invention.

[0156] Referring to FIG. 7, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can first increase a current variation time count for counting the number of times the current amount is determined to fluctuate (S700). The current variation time count is for periodically determining whether the current amount fluctuates, and the control unit (300) can increase the current variation time count every time the operation process of FIG. 7 is performed. In addition, when the current variation time count reaches a preset number, the current variation time count can be initialized.

[0157] And the control unit (300) can calculate the actual amount of current supplied during a certain period of time. Here, the certain period of time may be a time corresponding to a preset number of cycles of the alternating current. Therefore, the certain period of time may be set as the number of cycles or half cycles of the alternating current. In this case, if the certain period of time is one cycle of the alternating current, i.e., two half cycles, the control unit (300) can calculate the root mean square (RMS) value for the current samples during the half cycle (current half cycle) in which the current current sample and the high-frequency noise signal were collected and the half cycle prior to the current half cycle as the amount of current during the certain period of time (hereinafter, the first current RMS value, e.g., the 1-cycle current RMS value).

[0158] Meanwhile, the current amount detected before the above-mentioned predetermined time may be the current amount detected before a preset time from the above-mentioned predetermined time. For example, the preset time may be a time corresponding to 5 cycles of the AC current. In this case, the control unit (300) may calculate the root mean square (RMS) value for current samples during one cycle (2 half cycles) prior to 5 cycles, i.e. 10 half cycles, as the current amount detected before the above-mentioned predetermined time (hereinafter referred to as the second current RMS value, e.g., the current RMS value prior to 5 cycles) (S702).

[0159] In the following description, for the sake of convenience, it will be assumed that the first rms current value is the rms current value for one cycle, as in the example described above. In addition, it will be assumed that the second rms current value is the rms current value for one cycle prior to the fifth cycle, as in the example described above, i.e., the rms current value prior to the fifth cycle. However, it should be understood that the present invention is not limited thereto.

[0160] Then, the control unit (300) can calculate the current fluctuation value based on the calculated rms current value of the 1st cycle and the rms current value of the 5th cycle before (S704). In this case, the current fluctuation value may be the difference between the rms current value of the 1st cycle and the rms current value of the 5th cycle before.

[0161] When the current fluctuation value is calculated in the step S704, the control unit (300) can determine the current fluctuation reference value based on the root mean square (RMS) value for current samples during the current half-cycle and the half-cycle prior to the current half-cycle, that is, for one cycle, i.e., the one-cycle current RMS value (S706). In this case, if the one-cycle current RMS value is the first current RMS value (i.e., if the predetermined time is set to one cycle), the control unit (300) can determine the current fluctuation reference value based on the first current RMS value.

[0162] Here, the current fluctuation reference value may be determined to be larger as the current effective value during the one cycle increases. For example, when the current effective value during the one cycle is 2.0 A or less, the current fluctuation reference value may have a minimum value. The minimum value of the current fluctuation reference value may be a value preset by the manufacturer of the arc monitoring device according to an embodiment of the present invention or set by the user. In addition, the minimum value of the current fluctuation reference value may be a value determined based on experimental results obtained through a plurality of experiments related to the present invention.

[0163] If the current effective value during the above one cycle exceeds 2.0 A and is less than or equal to 3.5 A, the current fluctuation reference value may be set to twice the minimum value. In addition, if the current effective value during the above one cycle exceeds 3.5 A, the current fluctuation reference value may be set to three times the minimum value. That is, depending on the size of the current effective value during the above one cycle, the current fluctuation reference value may be determined as an integer multiple of the preset minimum value.

[0164] Meanwhile, when the current fluctuation reference value is determined in step S706, the control unit (300) can check whether the current fluctuation value calculated in step S704 is greater than or equal to the current fluctuation reference value determined in step S706 (S708).

[0165] If the check result of step S708 indicates that the current fluctuation value is greater than or equal to the current fluctuation reference value, the control unit (300) may determine that a current fluctuation has occurred (S715). In this case, the current fluctuation flag indicating whether the current fluctuation has occurred may be switched from an off state to an on state.

[0166] Then, the control unit (300) can initialize the current fluctuation time count counted up to now. The calculation results for detecting the current amount fluctuation can be initialized (S716). In this case, the calculated current fluctuation value and the currently determined current fluctuation reference value can be initialized. Then, the control unit (300) can proceed to step S700 again to increase the current fluctuation time count and perform the operation processes after step S700.

[0167] If the check result of the above step S708 shows that the current fluctuation value is less than the current fluctuation reference value, the control unit (300) can accumulate the current fluctuation value (S710).

[0168] In the above step S710, the control unit (300) can determine whether to accumulate the current fluctuation value based on the magnitude of the current fluctuation value. In addition, the current fluctuation value magnitude reference value for determining whether to accumulate the current fluctuation value can vary depending on the current fluctuation time count counted up to now.

[0169] Hereinafter, the operation process of step S710, which determines whether to accumulate the current fluctuation value calculated in step S704 based on different current fluctuation value size criteria to the current fluctuation value calculated up to that point, based on the current fluctuation time count counted up to now, will be examined in more detail with reference to FIG. 8.

[0170] Meanwhile, in the above step S710, when the current fluctuation value is accumulated, the control unit (300) can check whether the current fluctuation time count counted up to now has reached a preset value (S712). In other words, it can check whether the cycle for detecting the current fluctuation has expired.

[0171] If, as a result of the check in step S712, the current variation time count count counted so far has not reached a preset value, the control unit (300) can proceed to step S700 again to increase the current variation time count and perform the operation processes after step S700 again.

[0172] On the other hand, if the check result of the step S712 above shows that the current fluctuation time count counted up to now has reached a preset value, that is, if the preset current amount fluctuation cycle has expired, the control unit (300) can check whether the current fluctuation value accumulated up to now is greater than or equal to the current fluctuation reference value (S713).

[0173] If the current fluctuation value accumulated up to now is greater than the current fluctuation reference value as a result of the check in step S713, the control unit (300) may determine that a current fluctuation has occurred. Accordingly, the control unit may proceed to step S715 and switch the current fluctuation flag indicating whether the current fluctuation has occurred from the off state to the on state. Then, the control unit may proceed to step S716 and initialize the current fluctuation time count counted up to now and initialize the calculation results for detecting the current fluctuation. In this case, the current fluctuation value accumulated up to now and the current fluctuation reference value currently determined may be initialized. Then, the control unit (300) may proceed again to step S700 to increase the current fluctuation time count and perform the operation processes after step S700.

[0174] As a result of the check in step S713, if the current fluctuation value accumulated up to now is less than the current fluctuation reference value, the control unit (300) can determine that no current fluctuation has occurred. Accordingly, the current fluctuation occurrence determination state can be initialized (S714). Accordingly, the current fluctuation flag indicating whether the current fluctuation amount has occurred can be initialized to the OFF state. That is, if the current fluctuation flag is in the OFF state, the OFF state can be maintained as is, and if the current fluctuation flag is in the ON state, the OFF state can be switched.

[0175] Then, the control unit (300) can proceed to step S716 and initialize the current fluctuation time count count and the calculation results for detecting the current amount fluctuation. In this case, the accumulated current fluctuation value and the currently determined current fluctuation reference value can be initialized. Then, the control unit (300) can proceed to step S700 again to increase the current fluctuation time count and perform the operation processes after step S700.

[0176] FIG. 8 is a flowchart illustrating an operation process of accumulating current fluctuation values ​​according to different current fluctuation value size criteria based on the current fluctuation time count counted up to now in step S710 of the operation process of FIG. 7, as described above.

[0177] Referring to FIG. 8, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can check whether the current fluctuation time count counted up to now is less than or equal to a preset first value if the current fluctuation value is less than or equal to the current fluctuation reference value as a result of the check in step S708 of FIG. 7 (S800). In addition, whether or not the current fluctuation time count is less than or equal to the first value can be used as a basis for determining whether or not the current fluctuation value is accumulated based on different values.

[0178] That is, if the check result of the step S800 shows that the current fluctuation time count is less than or equal to the first value, the control unit (300) can check whether the current fluctuation value calculated in the step S704 is less than or equal to the preset first fluctuation minimum value (S802). On the other hand, if the current fluctuation time count is not less than or equal to the first value, that is, exceeds the first value, the control unit (300) can check whether the currently calculated current fluctuation value, that is, the current fluctuation value calculated in the step S704, is less than or equal to the preset second fluctuation minimum value (S801). Here, the first fluctuation minimum value may be a value smaller than the second fluctuation minimum value.

[0179] If the currently calculated current fluctuation value is less than or equal to the second fluctuation minimum value in step S801 or if the currently calculated current fluctuation value is less than or equal to the first fluctuation minimum value in step S802, the control unit (300) may not accumulate the currently calculated current fluctuation value to the previously calculated current fluctuation value. Accordingly, the control unit (300) may proceed to step S712 of FIG. 7 without accumulating the current fluctuation value and check whether the cycle for detecting the fluctuation of the current amount has expired. Then, the following steps may be performed depending on the check result of step S712.

[0180] On the other hand, if the currently calculated current fluctuation value exceeds the second fluctuation minimum value in step S801 or if the currently calculated current fluctuation value exceeds the first fluctuation minimum value in step S802, the control unit (300) may proceed to step S803 to accumulate the currently calculated current fluctuation value to the previously calculated current fluctuation value. Here, the previously calculated current fluctuation value is the current fluctuation value accumulated up to now, and may be the accumulated value of at least some of the current fluctuation values ​​calculated before the currently calculated current fluctuation value.

[0181] For example, if the cycle for detecting the change in the current amount is set to the current change value time count 4, the first value may be set to 2, which corresponds to 1 / 2 of the current change detection cycle.

[0182] In this case, the control unit (300) can check whether the current fluctuation time count counted up to the present in step S800 has reached 2, i.e., exceeds 2. If the counted current fluctuation time count is less than or equal to 2, the control unit (300) can proceed to step S802 to compare the currently calculated current fluctuation value with the first fluctuation minimum value. And, depending on the comparison result, the control unit can proceed to step S803 to accumulate the current fluctuation value.

[0183] On the other hand, if the counted current fluctuation time count exceeds 2, the control unit (300) can proceed to step S801 and compare the currently calculated current fluctuation value with the second fluctuation minimum value. Then, based on the comparison result, the control unit (300) can proceed to step S803 and accumulate the current fluctuation value.

[0184] Here, the first minimum fluctuation value may be smaller than the second minimum fluctuation value. For example, when the first minimum fluctuation value is set to 25, the second minimum fluctuation value may be set to 50. That is, the control unit (300) may compare the currently calculated current fluctuation value with different minimum fluctuation values ​​according to the current fluctuation time count value counted up to now, and accumulate the current fluctuation value according to the comparison result.

[0185] Meanwhile, as described above, the control unit (300) of the arc monitoring device according to the embodiment of the present invention has been described as detecting ignition in which the magnitude of the high-frequency noise signal increases by a certain level or more compared to before, along with the change in the amount of current, as a precursor phenomenon in which arc generation is expected, in step S502 of FIGS. 5 and 6.

[0186] FIG. 9 is a flowchart illustrating an operation process for detecting ignition, which is a precursor phenomenon to arc occurrence, in an arc monitoring device according to an embodiment of the present invention.

[0187] Referring to FIG. 9, the control unit (300) of the arc monitoring device can first check whether ignition has already occurred (S900). If ignition has already occurred, the operation process of FIG. 9 can be terminated without determining whether ignition has occurred.

[0188] Here, whether the ignition has occurred can be determined based on the state of the ignition flag indicating whether ignition has been detected. If the ignition flag is on, the control unit (300) can determine that ignition has already occurred, and if the ignition flag is off, the control unit (300) can determine that ignition has not occurred.

[0189] In the above step 900, if it is determined that the current ignition has not occurred, the control unit (300) can calculate the average value of the high-frequency noise signal magnitudes (hereinafter referred to as the current high-frequency noise average) during the half-cycle (current half-cycle) in which the current current sample and the high-frequency noise sample were acquired (S902). In addition, the average value of the high-frequency noise signal magnitudes accumulated for each half-cycle up to the current half-cycle (accumulated high-frequency noise average) can be calculated (S904).

[0190] Then, the control unit (300) can determine a first reference value according to a preset first ratio and a second reference value according to a preset second ratio for the calculated cumulative high-frequency noise average (S908). For example, when the first ratio is 25%, the first reference value can be determined as a value corresponding to 1 / 4 of the cumulative high-frequency noise average. In addition, when the second ratio is 20%, the second reference value can be determined as a value corresponding to 1 / 5 of the cumulative high-frequency noise average. Here, the first reference value can be determined as a value greater than the second reference value.

[0191] Here, the first reference value and the second reference value may be reference values ​​for determining whether ignition has occurred. That is, ignition is for detecting the occurrence of high-frequency noise due to an arc in a state where no high-frequency noise has occurred. In order to determine the reference values ​​according to the environment in which the arc monitoring device is placed, the first reference value (1 / 4 of the average of the accumulated high-frequency noise) and the second reference value (1 / 5 of the average of the accumulated high-frequency noise) may be determined based on the average of the accumulated high-frequency noise. In addition, if the currently detected high-frequency noise is greater than the above-mentioned reference value, it may be determined that ignition has occurred.

[0192] In more detail, the control unit (300) can compare the current high-frequency noise average calculated in step S902 with the first reference value (S910). If the comparison result of step S910 shows that the current high-frequency noise average is greater than or equal to the first reference value, the control unit (300) can determine that ignition has occurred during the current half cycle (S916). In this case, the ignition flag indicating that ignition has occurred can be switched to the on state.

[0193] Then, the control unit (300) can check whether the current event time count is initialized (S918). For example, if the value of the event time count accumulated to date is 1, the control unit (300) can determine that the event time count has been initialized. If the event time count has not been initialized, the control unit (300) can terminate the operation process of FIG. 9.

[0194] Then, when the current samples and high-frequency noise samples for a half cycle are collected again in steps S500 and S501 of FIG. 5 and step S502 of FIG. 5 is performed, the operation process of FIG. 9 for detecting whether the ignition occurred for the half cycle in which the current samples and high-frequency noise samples were collected can be performed again. That is, the operation process of FIG. 9 can be performed every time current samples and noise samples for a half cycle are acquired.

[0195] Meanwhile, if the event time count is initialized as a result of the check in step S918, the control unit (300) can initialize the ignition detection result (S920). Accordingly, the ignition flag that was in the on state can be switched to the off state. Alternatively, if the ignition flag is in the off state, the current state can be maintained. In addition, if step S502 is performed again after step S500 and step S501 in FIG. 5, the operation process of FIG. 9 can be performed again.

[0196] Meanwhile, if the comparison result of step S910 shows that the current high-frequency noise average is less than the first reference value, the control unit (300) can check whether the current high-frequency noise average is greater than or equal to the second reference value (S912). In addition, if the current high-frequency noise average is less than the second reference value, the control unit (300) can determine that ignition has not occurred during the current half cycle. Therefore, the process can proceed directly to step S918 without switching the ignition flag, and check whether the current event time count is initialized. In other words, the ignition flag can be maintained in an off state.

[0197] However, if the current high-frequency noise average is greater than or equal to the second reference value as a result of the check in step S912, the control unit (300) can check whether or not the current current fluctuation has occurred (S914). Here, whether or not the current fluctuation has occurred can be determined through the operation process of FIG. 7. That is, if the current fluctuation flag is in an off state through the operation process of FIG. 7, the control unit (300) can determine that the current current fluctuation has not occurred, and if the current fluctuation flag is in an on state, the control unit (300) can determine that the current current fluctuation has occurred.

[0198] If the check result of the above step S914 indicates that no current fluctuation has occurred, the control unit (300) can determine that ignition has not occurred during the current half cycle. Therefore, the control unit can proceed directly to step S918 without switching the ignition flag, and check whether the current event time count has been initialized. In other words, the ignition flag can be maintained in an off state.

[0199] On the other hand, if the check result of step S914 indicates that the current current fluctuation has occurred, the control unit (300) can determine that ignition has occurred during the current half cycle. Then, the control unit (300) can proceed to step S916 to turn on the ignition flag indicating that ignition has occurred, and proceed to step S918 to check whether the current event time count has been initialized. Then, depending on whether the event time count has been initialized, the control unit can proceed to step S920 to initialize the ignition detection result and end the operation process of FIG. 9.

[0200] That is, the control unit (300) can determine that ignition has occurred if the current high-frequency noise average is greater than or equal to a first reference value determined from the accumulated high-frequency noise average, and can determine that ignition has not occurred if the current high-frequency noise average is less than or equal to the second reference value. In addition, if the current high-frequency noise average is less than the first reference value and greater than or equal to the second reference value, it can determine whether ignition has occurred depending on whether a current amount fluctuation has occurred.

[0201] Meanwhile, in the above description, it has been explained that the operation process of FIG. 9 can be omitted depending on whether the ignition has already been detected in the S900 step.

[0202] However, unlike the above, it is of course possible to omit the operation process of FIG. 9 depending on whether the above-described accumulated high-frequency noise average is greater than a certain percentage of the current high-frequency noise average.

[0203] The above ignition may detect whether there is a certain level of increase in size proportional to the size of a typical high-frequency noise signal generated from the circuit. Accordingly, if the average size of the high-frequency noise signals detected during the current half cycle does not differ by a certain level from the size of a typical high-frequency noise signal, the occurrence of ignition may not be determined.

[0204] Accordingly, the control unit (300) can calculate the size of a typical high-frequency noise signal generated in the circuit through the accumulated high-frequency noise average, and check whether the calculated accumulated high-frequency noise average is equal to or greater than a certain percentage of the average size of high-frequency noise signals detected during the current half cycle, i.e., the current high-frequency noise average. For example, if the certain percentage is 25%, the control unit (300) can check whether the accumulated high-frequency noise average is equal to or greater than 25% of the current high-frequency noise average. If the accumulated high-frequency noise average is equal to or greater than 25% of the current high-frequency noise average, it can be determined whether ignition has occurred through the operation process of FIG. 9. On the other hand, if the accumulated high-frequency noise average is less than 25% of the current high-frequency noise average, the operation process of FIG. 9 can be terminated without determining whether ignition has occurred.

[0205] Therefore, the previously determined ignition occurrence status can be maintained. In other words, if the ignition occurrence was previously determined, the state in which the ignition occurrence was detected (ignition flag on) can be maintained. On the other hand, if the ignition occurrence was not previously determined, the state in which the ignition occurrence was not detected (ignition flag off) can be maintained.

[0206] And when the current samples and high-frequency noise samples for a half cycle are collected again in steps S500 and S501 of the above-described FIG. 5, the operation process of the above-described FIG. 9 for detecting whether the ignition occurred for the half cycle in which the current samples and high-frequency noise samples were collected can be performed again.

[0207] Meanwhile, the above current fluctuation and ignition may be precursor phenomena that are expected to cause an arc and may be phenomena that can be detected before the arc occurs. Accordingly, the arc monitoring device according to an embodiment of the present invention, as shown in FIG. 6, can detect not only the precursor phenomena but also phenomena that occur when an actual arc occurs, namely, zero sections and arc noise (whether a fluctuation in a high-frequency noise signal above a certain level occurs), thereby more accurately detecting whether an arc has occurred.

[0208] In this case, as shown in the above-described FIG. 6, the control unit (300) of the arc monitoring device according to the embodiment of the present invention may, when the precursor phenomenon (current fluctuation, ignition) is detected in the above-described S502 step, proceed to the above-described S600 step to further detect the zero section and arc noise (whether a fluctuation amount of a high-frequency noise signal above a certain level occurs), and may estimate whether an arc has occurred only when the zero section and arc noise are further detected.

[0209] FIG. 10 is a flowchart illustrating an operation process for detecting whether a zero section has occurred during a half cycle of an alternating current in an arc monitoring device according to an embodiment of the present invention in step S600 of FIG. 6. In addition, FIG. 11 is a flowchart illustrating an operation process for determining arc noise based on fluctuations in the maximum and average values ​​of high-frequency noise in step S600 of FIG. 6.

[0210] First, Fig. 10 is a flowchart illustrating an operation process for detecting the above zero section.

[0211] First, as described above, the zero section may refer to a section in which no current flows or current flows below a certain level due to a disconnected portion of a wire when the wire is partially disconnected due to insulation damage of the wire. For example, in the case of Fig. 4, which illustrates the current flow in the case of arc generation due to insulation damage, other stages (no-arc stage, arc strike stage, arc quench stage) other than the arc conduction state in which current flows due to an electric discharge (arc) generated by a high voltage may be sections corresponding to the zero section.

[0212] Therefore, the present invention enables the estimation of whether an arc has occurred by detecting a section corresponding to the zero section during a half cycle in which a current sample and a high-frequency noise sample are acquired.

[0213] Referring to FIG. 10, the control unit (300) can extract current samples whose current values ​​are within a threshold range according to a preset reference current value among the current samples during the currently acquired half-cycle (S1000). Here, the reference current value may be 0A, and thus, current samples whose current values ​​are within the threshold range may be regarded as current samples whose current values ​​are within the threshold range from 0A.

[0214] When current samples corresponding to a reference current value (e.g., 0A) are extracted in the above step S1000, the control unit (300) can detect consecutive samples that are greater than or equal to a preset number among the extracted current samples (S1002). Here, since the current samples are sampled according to a preset sampling interval, the current samples corresponding to the reference current value (e.g., 0A) that are greater than or equal to the preset number of consecutive samples can correspond to a section in which a current corresponding to the reference current value is detected for a certain period of time, i.e., a zero section.

[0215] Accordingly, if, as a result of the detection in step S1002, there are no consecutive samples greater than a preset number among the current samples corresponding to the reference current value (e.g., 0A), the control unit (300) can determine that the zero section is not included during the half-cycle in which the current current samples were acquired. Then, the control unit (300) can check whether it has entered the arc check cycle for checking whether an arc has occurred based on the event time count accumulated up to now (S1006).

[0216] However, if, as a result of the detection in step S1002, there are a preset number or more of consecutive samples among the current samples corresponding to the reference current value (e.g., 0A), the control unit (300) can determine that a zero section is included during the half cycle in which the current current samples were acquired. Accordingly, the control unit (300) can increase the zero count, which is a count indicating zero section detection (S1004). Then, when the zero count is increased, the control unit can proceed to step S1006 to check whether to enter the arc check cycle for checking whether an arc has occurred.

[0217] As a result of the check in step S1006, if the event time count accumulated up to now is less than the count value corresponding to the preset threshold time, the control unit (300) may determine that the arc check cycle has not been entered and may determine that the zero section has not been detected regardless of the zero count (S1012). In this case, the zero section flag indicating whether or not the zero section has been detected may be maintained in the off state.

[0218] Then, the control unit (300) can check whether the event time count is currently initialized (e.g., check whether the event time count is 1) (S1014). If the event time count is initialized, the zero count accumulated up to the present can be initialized (S1016). Accordingly, when the event time count is initialized and a new cycle for determining whether an arc has occurred begins, the zero count can be initialized.

[0219] On the other hand, if the event time count is not initialized as a result of the check in step S1014, the control unit (300) can terminate the operation process of FIG. 10 without initializing the zero count. Accordingly, the zero count increased in step S1004 can be maintained in an accumulated state. Then, when a current sample for another half cycle is acquired, the operation process of FIG. 10 is performed again, and the zero count can be increased and accumulated depending on the result of the determination of whether or not the zero section is included in step S1002.

[0220] Meanwhile, if the result of the check in step S1006 indicates that the event time count accumulated to date is greater than or equal to a count value corresponding to a preset threshold time, the control unit (300) may determine that the arc check cycle has been entered. Then, the control unit (300) may check whether the zero count accumulated to date has reached a preset zero count reference value (S1008).

[0221] Here, the zero count reference value may be determined based on the current amount (effective value) during the half cycle calculated in step S501 of FIG. 5. For example, the greater the current amount during the half cycle, the smaller the zero count reference value may be. Accordingly, the detection time of the zero section may become faster. On the other hand, the smaller the current amount during the half cycle, the larger the zero count reference value may be. Accordingly, the detection time of the zero section may become longer.

[0222] If the check result of the step S1008 above shows that the accumulated zero count up to now has not reached the preset zero count reference value, the control unit (300) may proceed to the step S1012 above and determine that the zero section has not been detected. In this case, the zero section flag indicating whether the zero section has been detected may remain in the off state. In addition, the control unit (300) may proceed to the step S1016 above and initialize the zero count or terminate the step as is, depending on the check result of the step S1014 above.

[0223] On the other hand, if the check result of the step S1008 above shows that the accumulated zero count up to now has reached the preset zero count reference value, the control unit (300) can determine that a zero section has been detected (S1010). In this case, the zero section flag indicating whether a zero section has been detected can be switched on. Then, the control unit (300) can proceed to the step S1016 above to initialize the zero count or terminate the step as is, depending on the check result of the step S1014 above.

[0224] Meanwhile, these zero sections can also be detected when the phase of the current supplied to a load is artificially controlled, depending on the type of load or the phenomenon related to arc. For example, when the load is a light, artificial phase control of the current supplied to the light can be utilized during dimming to limit the light output so that the light turns on at the brightness desired by the user.

[0225] In this dimming, since a current waveform having a controlled phase is formed using harmonics, a zero section according to the controlled phase can be detected. Therefore, to prevent misjudgment of whether a zero section is detected for arc detection due to this phase control, an arc monitoring device according to an embodiment of the present invention may further include a discrete Fourier transform unit (not shown) capable of detecting harmonics.

[0226] In this case, if it is determined in step S1002 of the above-described Figure 10 that the current half-cycle includes a zero section section, the frequency components of the current samples during the half-cycle can be detected based on the discrete Fourier transform operation result, including the fundamental component corresponding to the currently supplied AC current and the harmonic components for the fundamental component. Then, the ratio of the harmonic components to the fundamental component, i.e., the harmonic ratio, can be calculated.

[0227] Once the harmonic ratio is calculated, the control unit (300) can check whether the calculated harmonic ratio is greater than or equal to a preset ratio. In this case, if phase control is performed, such as the dimming, the harmonic component applied for the phase control can be detected, and thus, the harmonic component can be detected at a higher level than when phase control is not performed. Therefore, based on the harmonic ratio, it can be determined whether the current sample during the half cycle is in a phase control state or not.

[0228] Therefore, if the harmonic ratio is greater than or equal to the preset ratio, the zero section included in the current half-cycle current sample may be due to the phase control. Therefore, the control unit (300) can proceed to the next step, i.e., step S1006 of FIG. 10, without increasing the zero count. On the other hand, if the harmonic ratio is less than the preset ratio, the zero section included in the current half-cycle current sample may be due to insulation damage of the wire, i.e., arc generation. Therefore, the control unit (300) can increase the zero count (S1004) and proceed to the next step, i.e., step S1006 of FIG. 10.

[0229] Meanwhile, FIG. 11 is a flowchart illustrating an operation process for determining arc noise according to fluctuations in the maximum and average values ​​of high-frequency noise in an arc monitoring device according to an embodiment of the present invention.

[0230] Fig. 11 is a flowchart illustrating an operation process for determining whether arc noise is detected according to fluctuations in high-frequency noise in step S600 of Fig. 6. When step S600 of Fig. 6 is performed, the operation process of Fig. 11 described below may be performed to detect whether arc noise has occurred.

[0231] Referring to FIG. 11, the control unit (300) can calculate the average and maximum values ​​of the high-frequency noise samples during a half-cycle (previous half-cycle) prior to the current half-cycle in which the current sample and the high-frequency noise sample were acquired in order to detect whether there is a fluctuation in the high-frequency noise. In addition, the control unit can calculate the average and maximum values ​​of the high-frequency noise samples acquired during a half-cycle (hereinafter, “half-cycle prior to one cycle”) detected prior to a time corresponding to two half-cycles including the current half-cycle, that is, one cycle prior to the current half-cycle (S1100). In addition, the control unit (300) can calculate the average and maximum values ​​of the high-frequency noise samples acquired during the current half-cycle (S1102).

[0232] And the control unit (300) can calculate the amount of variation in the average value of the high frequency noise during the half cycle by subtracting the average value of the high frequency noise samples during the previous half cycle from the average value of the high frequency noise samples during the current half cycle. In addition, the control unit (300) can calculate the amount of variation in the maximum value of the high frequency noise during the half cycle by subtracting the maximum value of the high frequency noise samples during the previous half cycle from the maximum value of the high frequency noise samples during the current half cycle. That is, the average variation value and the maximum variation value of the high frequency noise during the half cycle can be calculated based on the average value and the maximum value of the high frequency noise samples during the current half cycle and the average value and the maximum value of the high frequency noise samples during the previous half cycle.

[0233] In addition, the control unit (300) can calculate the average value fluctuation of high-frequency noise during one cycle by subtracting the average value of high-frequency noise samples during the half cycle preceding the one cycle from the average value of high-frequency noise samples during the current half cycle. In addition, the control unit (300) can calculate the maximum value fluctuation of high-frequency noise during one cycle by subtracting the maximum value of high-frequency noise samples during the half cycle preceding the one cycle from the maximum value of high-frequency noise samples during the current half cycle. That is, the average value fluctuation and the maximum value fluctuation of high-frequency noise during one cycle can be calculated based on the average value and the maximum value of high-frequency noise samples during the current half cycle and the average value and the maximum value of high-frequency noise samples during the half cycle preceding the one cycle (S1104).

[0234] In the above step S1104, when the average fluctuation value and maximum fluctuation value of high frequency noise during a half cycle and the average fluctuation value and maximum fluctuation value of high frequency noise during one cycle are calculated, the control unit (300) can check whether the average fluctuation value of high frequency noise during the half cycle exceeds a preset reference value. In addition, it can check whether the maximum fluctuation value of high frequency noise during the one cycle exceeds a preset reference value (S1106).

[0235] And if the average change value of high-frequency noise during the above half cycle or the maximum change value of high-frequency noise during the above one cycle exceeds a preset reference value, it is determined that the high-frequency noise includes arc noise, and the arc noise count for arc noise detection can be increased (S1107).

[0236] However, if either the average change value of high-frequency noise during the above half cycle or the maximum change value of high-frequency noise during the above one cycle does not exceed the reference value, the S1107 step may be omitted and the arc noise count may not be increased.

[0237] And the control unit (300) can check whether the average fluctuation value of high-frequency noise during the one cycle exceeds a preset reference value. And it can check whether the maximum fluctuation value of high-frequency noise during the half cycle exceeds a preset reference value (S1108).

[0238] And if the average fluctuation value of high-frequency noise during the above one cycle or the maximum fluctuation value of high-frequency noise during the above half cycle exceeds a preset reference value, it is determined that the fluctuation amount of high-frequency noise includes arc noise, and the arc noise count for arc noise detection can be increased (S1110).

[0239] However, if either the average change value of high-frequency noise during the above one cycle or the maximum change value of high-frequency noise during the above half cycle does not exceed the reference value, the S1108 step may be omitted and the arc noise count may not be increased.

[0240] Therefore, if the average change value of high-frequency noise during a half cycle or the maximum change value of high-frequency noise during one cycle is less than or equal to a preset reference value in step S1106, the arc noise may not increase. In a state where the arc noise has not increased, step S1108 may be entered, and it may be checked whether the average change value of high-frequency noise during a half cycle or the maximum change value of high-frequency noise during one cycle exceeds a preset reference value. In addition, if the check result of step S1108 shows that the average change value of high-frequency noise during a half cycle or the maximum change value of high-frequency noise during one cycle is less than or equal to a preset reference value, the arc noise may not increase.

[0241] On the other hand, if the average change in high-frequency noise during a half cycle or the maximum change in high-frequency noise during one cycle exceeds a preset reference value in step S1106, the control unit (300) may proceed to step S1107 to increase the arc noise. If the check result in step S1108 shows that the average change in high-frequency noise during a half cycle or the maximum change in high-frequency noise during one cycle again exceeds a preset reference value, the control unit (300) may proceed to step S1110 to increase the arc noise again. That is, the arc noise may increase up to two times in steps S1107 and S1110.

[0242] And the control unit (300) can determine an arc noise count reference value for arc noise detection based on a preset threshold time (S1112). The arc noise count reference value can be determined according to a threshold time for determining whether the arc monitoring device according to an embodiment of the present invention has entered an arc check cycle for checking whether an arc has occurred. Here, the arc noise count reference value can be determined according to a certain ratio (e.g., 0.75 times) of the threshold time. That is, as the threshold time becomes longer (as the number of half-cycles corresponding to the threshold time becomes larger), the arc noise count reference value can be determined to be larger.

[0243] Meanwhile, when the arc noise count reference value is determined in step S1112, the control unit (300) can check whether the arc noise count accumulated up to now has reached the determined arc noise count reference value (S1114).

[0244] And if the result of the check in step S1114 shows that the arc noise count accumulated up to now has not reached the arc noise count reference value, the control unit (300) may proceed to step S1115 and determine that arc noise has not been detected. In this case, the arc noise flag indicating whether arc noise has been detected may be maintained in an off state. Then, the control unit (300) may check whether the event time count has been initialized in step S516 of FIG. 5 (S1118). If the event time count has been initialized, the arc noise count accumulated up to now may be initialized (S1120). Therefore, when the event time count has been initialized and a new cycle for determining whether an arc has occurred begins, the arc noise count may be initialized.

[0245] On the other hand, if the event time count is not initialized as a result of the check in step S1118, the control unit (300) can terminate the operation process of FIG. 11 without initializing the arc noise count. Accordingly, the accumulated state of the arc noise count increased in steps S1107 and S1110 can be maintained. Then, when a current sample for the next half cycle is acquired, the operation process of FIG. 11 is performed again, and the arc noise count can be increased and accumulated up to two times according to the check results in steps S1106 and S1108.

[0246] On the other hand, if the check result of the step S1114 above shows that the arc noise count accumulated up to now has reached the arc noise count reference value, the control unit (300) can determine that arc noise has been detected (S1116). In this case, the arc noise flag indicating whether arc noise has been detected can be switched on. Then, the control unit (300) can proceed to the step S1120 above to initialize the arc noise count or end the step as is, depending on the check result of the step S1118 above.

[0247] Meanwhile, in the above Fig. 11, it is explained that the arc noise count increases based on the variation of the average value and maximum value of the high-frequency noise, but if the variation of the current amount during the currently calculated half cycle is greater than that of the current amount during the previous half cycle or the half cycle one cycle ago, the increase in the arc noise count may be further accelerated.

[0248] Meanwhile, Fig. 12 is a flowchart illustrating an operation process for determining whether high-frequency noise corresponding to arc occurrence is included in an arc monitoring device according to an embodiment of the present invention. When step S508 of Fig. 5 or Fig. 6 is performed, the operation process of Fig. 12 described below may be performed to detect high-frequency noise corresponding to the arc occurrence.

[0249] Referring to FIG. 12, the control unit (300) can first calculate the average of the high-frequency noise samples collected during the current half-cycle (S1200). Then, the control unit (300) can calculate the cumulative average of the high-frequency noise samples collected for each half-cycle prior to the current half-cycle (S1202). In this case, the cumulative high-frequency noise average may be the cumulative average of the high-frequency noise samples collected during each half-cycle detected after the event time count is initialized. Alternatively, the cumulative average of the high-frequency noise samples collected during each half-cycle detected during a preset period. In this case, the cumulative high-frequency noise average may be the average of the high-frequency noise typically detected in the wire on which the arc monitoring is performed in the arc monitoring device according to the embodiment of the present invention.

[0250] When the above cumulative high-frequency noise average is calculated, the control unit (300) can determine the arc check level corresponding to arc occurrence based on the current effective value for the currently calculated half cycle (S1204).

[0251] Here, the arc check level may be set lower as the root mean square (RMS) current value during the current half cycle increases. On the other hand, the arc check level may be set higher as the root mean square (RMS) current value during the current half cycle decreases. For example, if the root mean square (RMS) current value during the current half cycle is 20 A or more, the arc check level may be set to 5. On the other hand, if the root mean square (RMS) current value during the current half cycle is less than 2.5 A, the arc check level may be set to 20.

[0252] Meanwhile, different arc check levels may correspond to different high-frequency noise values ​​(e.g., signal strength). A higher arc check level may correspond to a larger high-frequency noise value.

[0253] When the arc check level is determined in step S1204, the control unit (300) can determine an accumulated arc check level to be compared with the accumulated high-frequency noise average based on the determined arc check level (S1206). In this case, the accumulated arc check level can be determined according to a certain ratio of the arc check level determined in step S1204. That is, the accumulated arc check level does not exceed the arc check level determined in step S1204, and can increase or decrease in proportion to the size of the arc check level. For example, the accumulated arc check level can be determined as half of the arc check level.

[0254] Once the above cumulative arc check level is determined, the control unit (300) can compare the high-frequency noise average for the current half-cycle calculated in step S1200 with the high-frequency noise value according to the arc check level calculated in step S1204 (S1208).

[0255] That is, the arc check level is a level for determining a reference value (reference high frequency noise value) for determining whether an arc has occurred based on the magnitude of the detected high frequency noise, and a corresponding high frequency noise value (e.g., signal intensity) can be designated for each level. Then, when the arc check level is determined, the control unit (300) can compare the high frequency noise value corresponding to the determined arc check level with the average of the high frequency noise measured during the current half cycle, thereby determining whether the high frequency noise corresponding to the arc occurrence is included during the current half cycle.

[0256] Accordingly, if the comparison result of step S1208 shows that the average high-frequency noise during the current half-cycle is lower than or equal to the high-frequency noise value according to the arc check level, the control unit (300) can determine that the current half-cycle in which the high-frequency noise sample is collected does not include high-frequency noise corresponding to arc occurrence (S1214). In this case, the arc check level flag indicating whether high-frequency noise corresponding to the arc occurrence is detected can be maintained in the off state. Accordingly, the control unit (300) can proceed to step S507 of FIG. 5, which deducts the arc check count accumulated up to the present in step S508 of FIG. 5.

[0257] Meanwhile, if the comparison result of the step S1208 indicates that the high-frequency noise average for the current half-cycle exceeds the high-frequency noise value according to the arc check level, the control unit (300) can check whether the cumulative high-frequency noise average calculated in the step S1202 exceeds the high-frequency noise value according to the cumulative arc check level determined in the step S1206 (S1210).

[0258] And if the result of the check in step S1210 is that the accumulated high-frequency noise average is lower than or equal to the high-frequency noise value according to the accumulated arc check level, the control unit (300) may proceed to step S1214 and determine that the half-cycle in which the current high-frequency noise sample is collected does not include high-frequency noise corresponding to arc occurrence. Accordingly, the arc check level flag indicating whether high-frequency noise corresponding to arc occurrence is detected may be maintained in the off state. Then, the control unit (300) may proceed to step S507 of FIG. 5 to deduct the arc check count accumulated up to the present in step S508 of FIG. 5.

[0259] On the other hand, if the result of the check in step S1210 is that the accumulated high-frequency noise average exceeds the high-frequency noise value according to the accumulated arc check level, the control unit (300) can determine that the current half-cycle in which the high-frequency noise sample is collected includes high-frequency noise corresponding to arc occurrence, i.e., arc noise (S1212). In this case, the arc check level flag indicating whether the arc noise is detected can be switched to an on state. Then, the control unit (300) can proceed to step S510 of FIG. 5, which increases the arc check count accumulated up to the present in step S508 of FIG. 5.

[0260] Meanwhile, according to the description of FIG. 5 described above, the control unit (300) of the arc monitoring device according to the embodiment of the present invention increases the event time count each time current samples and high-frequency noise samples acquired during a half cycle are acquired, and initializes the event time count when the event time count reaches a preset reference time count, thereby initializing the event time count at a certain time interval (hereinafter, “event time”). Accordingly, the present invention can prevent the current occurrence of an arc from being determined based on an arc estimation result prior to the event time.

[0261] Meanwhile, in this case, since whether an arc occurs is determined at each event time determined according to the reference time count, the load on the arc monitoring device may be increased. Therefore, even if the reference time count is not reached when a preset condition is met, the event time count may be initialized so that the time for the event time count to reach the reference time count is delayed. In this case, as a result, the time required for the event time count to reach the reference time count again after reaching the reference time count, i.e., the event time, is increased, so that the time required to determine whether an arc occurs may be delayed. In addition, the load on the arc monitoring device may be somewhat reduced according to this time delay.

[0262] FIG. 13 is a flowchart illustrating an operation process of delaying the expiration of an event time for determining whether an arc has occurred when a preset condition is met in an arc monitoring device according to an embodiment of the present invention.

[0263] Referring to FIG. 13, the control unit (300) of the arc monitoring device can calculate the cumulative average of the high-frequency noise averages calculated for each event time up to now, hereinafter referred to as the high-frequency noise history average (S1300).

[0264] Once the above high-frequency noise history average is calculated, the control unit (300) can check whether the high-frequency noise history average is less than or equal to a preset first delay reference value (S1302). If the check result of step S1302 determines that the high-frequency noise history average exceeds the first delay reference value, it can be determined that the condition for the delay of the event time is not met. Then, the control unit (300) can proceed to step S1300 again to calculate the high-frequency noise history average.

[0265] However, if the high-frequency noise history average is less than or equal to the first delay reference value as a result of the check in step S1302, it is possible to check whether the arc check cycle has been entered in which the occurrence of an arc is checked within the current event time based on the event time count counted up to now (S1304).

[0266] And if the check result of the step S1304 above shows that the arc check cycle has not been entered, the average size of the high-frequency noise signals of each half-cycle detected up to the present after the event time count is initialized (hereinafter, short-term high-frequency noise average) can be calculated. And the control unit (300) can proceed to step S1300 again to calculate the high-frequency noise history average.

[0267] On the other hand, if the result of the check in step S1304 indicates that the arc check period has been entered, the control unit (300) can calculate the average size (hereinafter referred to as the cumulative high-frequency noise average) of the high-frequency noise signals of each half-cycle detected up to the present after the event time count is initialized (S1306). In this case, the cumulative high-frequency noise average may be a cumulative average in which the average size of the high-frequency noise signals of each half-cycle detected after entering the arc check period is further reflected in the short-term high-frequency noise average.

[0268] When the cumulative high-frequency noise average is calculated in step S1306, the control unit (300) can first check whether the short-term high-frequency noise average is less than or equal to a preset second delay reference value (S1308). Then, if the check result in step S1308 shows that the short-term high-frequency noise average is less than or equal to the preset second delay reference value, the control unit (300) can check whether the cumulative high-frequency noise average is less than or equal to a preset third delay reference value (S1310).

[0269] And if, as a result of the check in step S1310, the accumulated high-frequency noise average is less than or equal to the third delay reference value, the control unit (300) can determine that the condition for delaying the event time is satisfied. Accordingly, the control unit (300) can initialize the event time count even though the reference time count has not been reached (S1312).

[0270] However, if the short-term high-frequency noise average exceeds the second delay reference value in step S1308 or step S1310, or the accumulated high-frequency noise average exceeds the third delay reference value, the control unit (300) determines that the condition for the delay of the event time is not met and proceeds to step S1300 again to calculate the high-frequency noise history average.

[0271] Meanwhile, if the conditions that the high-frequency noise history average is less than or equal to the first delay reference value, the short-term high-frequency noise average is less than or equal to the second delay reference value, and the accumulated high-frequency noise average is less than or equal to the third delay reference value are satisfied, the event time count count counted up to now can be initialized. Here, the first delay reference value may be a value smaller than the second delay reference value. In addition, the second delay reference value may be a value smaller than the third delay reference value.

[0272] Therefore, the expiration time of the event time can be delayed by the time corresponding to the event time count counted so far. That is, when the event time count count counted so far is 50 (50 half-cycles), if the event time count is initialized according to the operation process of FIG. 13, assuming that the reference time count is set to 60 (60 half-cycles), the reference time count can be reached only after the time corresponding to 60 half-cycles elapse again. Therefore, the time until the reference time count is reached again, that is, the event time, can be increased to the time when 110 (50 + 60) half-cycles elapse.

[0273] The present invention described above can be implemented as computer-readable code on a medium having a program recorded thereon. Computer-readable media include all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid-state disks (SSDs), silicon disk drives (SDDs), ROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc., and also include media implemented in the form of carrier waves (e.g., transmission via the Internet). Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. A high-frequency signal detection unit that detects a high-frequency signal from the current flowing in the circuit; A circuit breaker that blocks the electrical connection between the power source and the load by blocking the above circuit; A voltage detection unit that detects a voltage change in the above circuit; A current detection unit that detects a change in current in the above circuit; and Ignition, which is a precursor phenomenon of arc occurrence, is detected based on the difference between the average magnitude of the high-frequency signal accumulated before the half-cycle of the current and the average magnitude of the high-frequency signal detected during the half-cycle of the current, and current fluctuation is detected based on the difference between the amount of current detected during one cycle of the current and the amount of current detected during one cycle of the current before a preset time. When the above ignition and current fluctuation are detected, whether an arc occurs during the half cycle is estimated based on the average size of the high-frequency signal collected during the half cycle of the current. An arc monitoring device characterized by including a control unit that determines whether an arc has occurred in the circuit based on whether the estimated number of arc occurrences is greater than a preset allowable number of occurrences, and controls the circuit blocking unit to block the circuit based on the determination result.

2. In the first paragraph, the control unit, The first current rms value, which is the current rms value for one cycle of the current, is calculated, and the second current rms value, which is the current rms value for one cycle of the current before a preset time, is calculated. Calculate the current fluctuation value based on the difference between the first and second current effective values, An arc monitoring device characterized in that it detects that the current fluctuation has occurred when the calculated current fluctuation value is greater than or equal to a current fluctuation reference value determined according to the first current effective value.

3. In the second paragraph, the control unit, If the current fluctuation value is less than the current fluctuation reference value, the current fluctuation value is accumulated, An arc monitoring device characterized in that it detects that a current fluctuation has occurred when the accumulated current fluctuation value is greater than the current fluctuation reference value.

4. In the third paragraph, the control unit, Count the number of times the above current fluctuation value is produced, An arc monitoring device characterized in that it compares a current fluctuation value size standard determined differently based on the number of counts with the current fluctuation value and accumulates the current fluctuation value to the previously accumulated current fluctuation value based on the comparison result.

5. In the first paragraph, the control unit, A first average value, which is an average value of the high-frequency noise signal sizes detected during the half-cycle of the current, is calculated, and a second average value, which is an accumulated average value of the high-frequency noise signal sizes detected before the half-cycle of the current, is calculated. Determine the first reference value and the second reference value according to the first ratio and the second ratio set in advance for the above second average value, Whether the ignition has occurred is detected based on the result of comparing at least one of the first reference value and the second reference value with the first average value, An arc monitoring device characterized in that the first ratio is greater than the second ratio.

6. In paragraph 5, the control unit, If the above first average value is greater than or equal to the above first reference value, or An arc monitoring device characterized in that it detects that ignition has occurred when the first average value is less than the first reference value and greater than the second reference value in a state where the current fluctuation is detected.

7. In the first paragraph, the control unit, When the above ignition and the above current fluctuation are detected, a zero section according to the time at which a current value within a critical range from the reference current is detected during a half cycle of the current, and arc noise according to the amount of fluctuation of the high-frequency signal are further detected. An arc monitoring device characterized in that it estimates whether the arc occurs during the half cycle based on the intensity average of the high-frequency signal when the zero section and the arc noise are further detected.

8. In paragraph 7, the control unit, Whether the zero section occurs is estimated based on whether a preset number or more of samples having a voltage value within the threshold range are detected among the current samples extracted during the above half-cycle. An arc monitoring device characterized in that it is determined that the zero section has been detected when the zero count value, which is the accumulated number of estimated zero sections for each half-cycle, reaches a preset zero count reference value.

9. In paragraph 8, the control unit, If the above zero section is estimated, a discrete Fourier transform is further performed to analyze the frequency components of the current values ​​detected during the half cycle of the current. An arc monitoring device characterized in that the zero section is re-estimated based on the ratio of the fundamental wave and harmonic wave detected as a result of frequency component analysis.

10. In paragraph 7, the control unit, An arc monitoring device characterized in that, if any one of the above current fluctuation, the ignition, the zero section and the arc noise is not detected, the number of arc occurrences estimated up to now is initialized.

11. In the first paragraph, the control unit, Calculate the effective value of the current values ​​detected during the half cycle of the above current, An arc monitoring device characterized in that the number of arc occurrences estimated up to now is reset if the calculated effective value does not exceed a preset minimum value.

12. In the 11th paragraph, the control unit, The above allowable number of times is determined based on the calculated effective value above, The above allowable number of times is, An arc monitoring device characterized in that the larger the calculated effective value, the smaller the value is determined.

13. In the first paragraph, the control unit, It determines whether the half-cycle of the above current has entered the arc check cycle for detecting whether an arc has occurred within a critical time determined by the number of preset half-cycles. An arc monitoring device characterized in that, if the half-cycle of the current is not a half-cycle included in the arc check period, the estimated number of arc occurrences estimated up to now is deducted.

14. A first step of sampling the current signal and high-frequency signal during a half cycle of the current flowing in the circuit; A second step is to increment the event time count to check the elapsed time; A third step of detecting current fluctuations according to the difference between the amount of current detected during one cycle of the current and the amount of current detected during one cycle of the current prior to a preset time; A fourth step of detecting ignition, which is a precursor phenomenon of arc occurrence, based on the difference between the average magnitude of the high-frequency signal accumulated before the half-cycle of the current and the average magnitude of the high-frequency signal detected during the half-cycle of the current; A fifth step of estimating whether an arc (ARC) occurs during a half cycle of the current based on the average intensity of the high-frequency signal when the current fluctuation and the ignition are detected; A sixth step of increasing the estimated number of arc occurrences when arc occurrence is estimated and checking whether the number of arc occurrences accumulated to date is greater than the preset allowable number; A seventh step of cutting off the electrical connection between the power source and the load by cutting off the circuit when the number of accumulated arc occurrences is greater than the allowable number; A control method for an arc monitoring device, characterized in that it includes an eighth step of initializing the event time count depending on whether the accumulated event time count has reached a preset number of half-cycles corresponding to a preset threshold time when the accumulated number of arc occurrences is less than the allowable number.

15. In paragraph 14, the third step is, Step 3-1 of calculating the first current effective value, which is the current effective value for one cycle of the above current; Step 3-2 of calculating the second current root mean square value, which is the current root mean square value for one cycle of the current prior to a preset time; Step 3-4 of calculating a current fluctuation value based on the difference between the first and second current effective values; A control method for an arc monitoring device, characterized in that it includes a 3rd to 4th step of detecting that the current fluctuation has occurred when the calculated current fluctuation value is greater than or equal to a current fluctuation reference value determined according to the first current effective value.

16. In the 15th paragraph, the steps 3-4 are: Step a of accumulating the current fluctuation value when the current fluctuation value is less than the current fluctuation reference value; and, It further includes a step b for detecting that the current fluctuation has occurred when the accumulated current fluctuation value is greater than the current fluctuation reference value. Step b above, Step b-1, which determines the current fluctuation value size standard differently based on the number of times the current fluctuation value is calculated; and, A control method for an arc monitoring device, characterized in that it includes a step b-2 of accumulating the current fluctuation value to the previously accumulated current fluctuation value based on the result of comparing the current fluctuation value size standard determined in the step b-1 with the current fluctuation value.

17. In paragraph 15, the fourth step is, Step 4-1 of calculating a first average value, which is an average value of the high-frequency noise signal sizes detected during the half-cycle of the current, and calculating a second average value, which is an accumulated average value of the high-frequency noise signal sizes detected before the half-cycle of the current; Step 4-2 of determining a first reference value and a second reference value according to a first ratio and a second ratio set in advance for the second average value; and, A step 4-3 for detecting whether the ignition has occurred based on a result of comparing at least one of the first reference value and the second reference value with the first average value, A control method for an arc monitoring device, characterized in that the first ratio is greater than the second ratio.

18. In paragraph 15, the fifth step is: Step 5-1 of detecting a zero section according to a time during which a current value within a critical range from a reference current is detected during a half cycle of the current when the above current fluctuation and the ignition are detected; Step 5-2 further detecting arc noise according to the fluctuation amount of high-frequency signal; and, A control method of an arc monitoring device, characterized in that it includes a step 5-3 of estimating whether an arc occurs during a half cycle of the current based on an intensity average of the high-frequency signal when the zero section and the arc noise are further detected.

19. In paragraph 18, step 5-1, Step c of estimating whether the zero section has occurred based on whether a preset number or more of samples having a voltage value within the threshold range among the current samples extracted during the above half-cycle are detected; and, A control method for an arc monitoring device, characterized in that it includes a step d for determining that the zero section is detected when the zero count value, which is the accumulated number of estimated zero sections for each half-cycle, reaches a preset zero count reference value.

20. In paragraph 19, step d is, Step d-1 of analyzing the frequency components of the current values ​​detected during the half cycle of the current by performing a discrete Fourier transform when the above zero section is estimated; and, A control method for an arc monitoring device, characterized in that it includes a step d-2 of re-estimating the zero section according to the ratio of the fundamental wave and harmonic wave detected as a result of the frequency component analysis.

21. In paragraph 18, step 5-2, Step e of calculating the average and maximum values ​​of the high-frequency signals detected during the half cycle of the above current; Step f of comparing the calculated average value and maximum value with the average value and maximum value of the high-frequency signal detected during a half cycle prior to the half cycle of the current, and the average value and maximum value of the high-frequency signal detected during a half cycle prior to one cycle from the half cycle of the current, to calculate the high-frequency signal fluctuation value during a half cycle and the high-frequency signal fluctuation value during one cycle; Step g of increasing at least one arc noise count for estimating whether arc noise has occurred based on the results of comparing the high-frequency signal fluctuation value during the generated half-cycle and the high-frequency signal fluctuation value during the one-cycle with the preset high-frequency signal minimum value; and A control method of an arc monitoring device, characterized in that it includes a step h for estimating that the arc noise has occurred when the increased arc noise count is greater than a preset arc noise count reference value.

22. In paragraph 18, the fifth step is: An arc monitoring device characterized by further comprising a step 5-4 of initializing the number of arc occurrences estimated up to now, if any one of the current fluctuation, the ignition, the zero section and the arc noise is not detected.

23. In paragraph 14, the fifth step is: Step 5-5 of calculating the effective value of the current values ​​detected during the half cycle of the above current; It further includes steps 5-6 of initializing the number of arc occurrences estimated up to now if the calculated effective value does not exceed the preset minimum value. Step 5-5 above, It further includes a step i that determines the allowable number of times based on the calculated effective value, The above allowable number of times is, A control method for an arc monitoring device, characterized in that the larger the calculated effective value, the smaller the value is determined.

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