Arc monitoring device and control method thereof

Abstract

The present invention relates to an arc monitoring device. The arc monitoring device comprises: a high-frequency signal detection unit that detects a high-frequency signal from a power circuit; a blocking unit that blocks the power circuit to block a connection between a power supply and a load; a voltage detection unit that detects a voltage change in the power circuit; a current detection unit that detects a current change in the power circuit; and a control unit that detects a ZCP, which is a point in time at which a reference voltage appears according to a phase alternation of a voltage from the voltage change, detects a zero section according to a time during a half-cycle of a current between ZCPs at which a current value within a threshold range from a reference current is detected, detects arc noise according to a variation in the high-frequency signal, estimates whether arc occurs during the half-cycle on the basis of an average intensity of the high-frequency signal in a case in which the zero section and the arc noise are detected, determines whether arc occurs on the basis of whether the estimated number of times of arc occurrences is greater than or equal to an allowable number of times, and blocks the power circuit according to a result of the determination.

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 uses the magnitude of the high-frequency component of the detected noise to detect the occurrence of an arc. However, current arc detection devices only determine whether an arc has occurred based on the magnitude of a specific high-frequency component detected from the current noise, which limits their ability to distinguish between typical current noise and arcs. Consequently, there is a problem that the accuracy of arc detection is not high, such as misidentifying noise as arcs or misjudging arcs 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 comprises: 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; a zero crossing point, which is a point in time having a reference voltage according to a phase alternation of voltage from the voltage change, and a zero section according to a time at which a current value within a critical range from the reference current is detected during a half cycle of the current corresponding to between zero crossing points; and an arc noise according to a fluctuation amount of a high-frequency signal; and when the zero section and the arc noise are detected, whether an arc (ARC) occurs during the half cycle is estimated based on an intensity average of the high-frequency signal; and whether an arc has occurred in the electric circuit is determined based on whether the estimated number of arc occurrences is greater than or equal to a preset allowable number of occurrences, and the blocking unit is controlled to block the electric circuit according to the determination result. It is characterized by including a control unit.

[0009] 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.

[0010] 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.

[0011] In one embodiment, the control unit is characterized in that, if the zero section and arc noise are both not detected as a result of detection of the zero section and arc noise, the number of arc occurrences estimated up to now is initialized.

[0012] In one embodiment, the control unit calculates the root mean square values ​​of current values ​​detected during a half cycle of the current, and determines the allowable number of times based on the calculated root mean square values, and the allowable number of times is determined to be smaller as the calculated root mean square value increases.

[0013] In one embodiment, the control unit is characterized in that, when both the zero section and the arc noise are detected, the calculated effective value does not exceed a preset minimum value, and the number of arc occurrences estimated up to now is initialized.

[0014] In one embodiment, the control unit detects a change in current magnitude during a half-cycle of the current by comparing the calculated root mean square value with the root mean square value of the current during a half-cycle prior to the half-cycle of the current, estimates a zero section from current samples acquired during the half-cycle according to the detected change in current magnitude, and determines that the zero section is 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.

[0015] In one embodiment, the control unit is characterized in that, when both the zero section and the arc noise are detected, it determines whether the half-cycle of the current has entered an arc check period for detecting whether an arc has occurred within a threshold period 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, it deducts the estimated number of arc occurrences estimated up to now.

[0016] In one embodiment, the control unit is characterized in that, when the zero crossing point is detected, the control unit increases an event time count for counting the time elapsed during the critical period, and when the increased event time count reaches a preset number, it is determined that the arc check period has been entered.

[0017] In one embodiment, the control unit is characterized in that, when the event time count reaches a preset number of half-cycles corresponding to the critical period, the event time count is initialized, and the number of arc estimates counted before the critical period is deducted from the number of arc estimates accumulated up to now.

[0018] In one embodiment, the control unit calculates an average value and a maximum value of a high-frequency signal detected during a half cycle of the current, and compares 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 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, thereby calculating a high-frequency signal fluctuation value during a half cycle and a high-frequency signal fluctuation value during one cycle, and based on the results of comparing the calculated high-frequency signal fluctuation value during a half cycle and the high-frequency signal fluctuation value during one cycle with a preset high-frequency signal minimum value, increases an arc noise count for estimating whether or not arc noise has occurred by at least one, and when the increased arc noise count is equal to or greater than a preset arc noise reference value, it is estimated that the arc noise has occurred.

[0019] In one embodiment, the control unit is characterized in that it determines whether the root mean square values ​​of the current values ​​have changed based on the root mean square values ​​of the current values ​​detected during a half cycle of the current and the root mean square values ​​of the current values ​​detected during a half cycle prior to one cycle, and additionally increases the arc noise count when the root mean square values ​​of the current values ​​have changed.

[0020] In one embodiment, the control unit is characterized in that it receives the zero crossing point detected according to the voltage change of the voltage detection unit as an interrupt signal, and starts sampling the current signal and the high-frequency signal when the interrupt signal is received.

[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 detecting a zero crossing point, which is a point in time having a reference voltage according to a voltage change of a current flowing in a circuit; a second step of sampling a current signal and a high-frequency signal during a half cycle of the current corresponding to the detected zero crossing point and the zero crossing point when the zero crossing point is detected; a third step of increasing an event time count for checking an elapsed time; a fourth step of detecting whether a zero section exists according to a time at which a current value within a critical range from a reference current is detected based on current samples acquired during the half cycle of the current; a fifth step of detecting arc noise according to a variation of a high-frequency signal based on high-frequency signal samples acquired during the half cycle of the current; a sixth step of estimating whether an arc (ARC) occurs during the half cycle based on an intensity average of the high-frequency signal when the zero section and arc noise are detected; and a sixth step of increasing the estimated number of arc occurrences when the arc occurrence is estimated, and calculating the number of arc occurrences accumulated to date. It is characterized by including a seventh step of checking whether the number of arc occurrences is greater than or equal to a preset allowable number, an eighth step of cutting off the electrical connection between the power source and the load by blocking the electric circuit if the accumulated number of arc occurrences is greater than or equal to the allowable number, a ninth step of checking whether the accumulated event time count has reached a preset number of half-cycles corresponding to a preset critical period if the accumulated number of arc occurrences is less than the allowable number, and a tenth step of initializing the event time count if the accumulated event time count has reached a preset number of half-cycles corresponding to the critical period.

[0022] In one embodiment, the method further includes a step 10-1 of deducting a count of the number of occurrences of an arc counted before a preset time from the accumulated number of occurrences of the arc, wherein the preset time is a time corresponding to a preset number of half-cycles corresponding to the critical period.

[0023] In one embodiment, the fourth step is characterized by including a step 4-1 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 are detected, and a step 4-2 of determining 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.

[0024] In one embodiment, the fourth step is characterized by further including a step 4-3 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 4-4 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.

[0025] In one embodiment, the fourth step is characterized by including a fourth-fifth step of detecting a change in current magnitude during a half-cycle of the current by comparing the calculated root mean square value with the root mean square value of the current during a half-cycle prior to the half-cycle of the current, a fourth-sixth step of estimating a zero section during the half-cycle based on the detected change in current magnitude, and a fourth-seventh step of determining that the zero section is detected when a zero count value, which is an accumulated number of zero sections estimated for each half-cycle, reaches a preset zero count reference value.

[0026] In one embodiment, the fifth step is characterized by including a step 5-1 of calculating an average value and a maximum value of a high-frequency signal detected during a half cycle of the current, a step 5-2 of 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 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, to calculate a high-frequency signal fluctuation value during a half cycle and a high-frequency signal fluctuation value during one cycle, a step 5-3 of 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 the half cycle and the high-frequency signal fluctuation value during the one cycle with a preset high-frequency signal minimum value, and a step 5-4 of 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.

[0027] In one embodiment, the fifth step is characterized by further including a fifth step of determining whether the root mean square values ​​of the current values ​​have changed based on the root mean square values ​​of the current values ​​detected during the half cycle of the current and the root mean square values ​​of the current values ​​detected during the half cycle prior to one cycle, and a fifth step of further increasing the arc noise count if the root mean square values ​​of the current values ​​have changed.

[0028] In one embodiment, the sixth step is characterized by including a sixth-first step of initializing the number of arc occurrences estimated up to now if, as a result of detection of the zero section and arc noise, neither the zero section nor the arc noise is detected.

[0029] In one embodiment, the second step is characterized in that it calculates the root mean square value of the current values ​​detected during the half cycle of the current, and determines the allowable number of times based on the calculated root mean square value, and the allowable number of times is determined to be smaller as the calculated root mean square value increases.

[0030] In one embodiment, the sixth step is characterized by including a sixth-second step of initializing the number of arc occurrences estimated up to now if both the zero section and the arc noise are detected and the calculated effective value does not exceed a preset minimum value.

[0031] In one embodiment, the sixth step is characterized by including a 6-3 step of determining whether the event time count has entered an arc check period for detecting whether an arc has occurred within the threshold period, based on whether the number of half-cycles corresponding to a preset threshold period has been reached when both the zero section and the arc noise are detected, and a 6-4 step characterized by deducting the estimated number of arc occurrences estimated up to now when the event time count has not entered the arc check period.

[0032] The effects of the arc monitoring device and the arc monitoring device control method according to the present invention are described as follows.

[0033] According to at least one embodiment of the present invention, the present invention determines whether an arc has occurred by considering not only the magnitude of high-frequency noise but also the fluctuation of the high-frequency noise and the shoulder phenomenon caused by insulation damage, 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 internal power devices due to the occurrence of the series arc.

[0034] 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.

[0035] 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.

[0036] Figure 1 is a conceptual diagram to explain the types of arcs according to their cause of occurrence.

[0037] Figure 2 is an example diagram showing an example of arc noise appearing in a wide frequency band in the form of white noise.

[0038] FIG. 3 is a block diagram illustrating the configuration of an arc monitoring device according to an embodiment of the present invention.

[0039] Figure 4 is a diagram showing typical high-frequency arc noise and high-frequency noise and current and voltage changes when an arc occurs.

[0040] 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.

[0041] FIG. 6 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.

[0042] Fig. 7 is a flowchart illustrating an operation process of increasing a zero count based on a harmonic ratio during the operation process of Fig. 6.

[0043] FIG. 8 is a flowchart illustrating another operation process for detecting whether a zero section has occurred during the half cycle based on the current effective value in an arc monitoring device according to an embodiment of the present invention.

[0044] FIG. 9 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.

[0045] Figure 10 is a flowchart illustrating an operation process in which arc noise count accumulation is accelerated based on the amount of current fluctuation.

[0046] FIG. 11 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] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Figure 1 is a conceptual diagram to explain the types of arcs according to their cause of occurrence.

[0052] 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'.

[0053] 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.

[0054] 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).

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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).

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] Meanwhile, the HFCT (High Frequency Current Transformer) (330) is a sensor for detecting a high-frequency noise signal of a current flowing in a circuit, and may be formed so that any one of the circuits passes through it. In addition, the HFCT (330) may include at least one sensor for detecting 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.

[0066] 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.

[0067] 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 an analog-type high-frequency current signal 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.

[0068] And the control unit (300) controls each component of the arc monitoring device and can control the overall operation of the arc monitoring device.

[0069] The control unit (300) can receive the amplified high-frequency noise signal through the amplification unit (332). Then, the control unit (300) 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., a half-cycle of a single-phase current), and determine whether the current value is within a critical range from the reference current (e.g., 0 A), i.e., a zero section, based on the detection result. In addition, it can determine whether a fluctuation in the high-frequency noise has occurred based on the detection result, and can estimate whether the high-frequency noise corresponding to the arc occurrence has occurred (estimation of the arc occurrence) based on a reference value determined according to the current current level. Then, when a half-cycle (hereinafter, “half-cycle”) of the single-phase current estimated to include the high-frequency noise corresponding to the arc occurrence is detected more than a preset number of times during a preset period of time, it can be determined that an arc has occurred.

[0070] First, the control unit (300) can detect the zero crossing point (ZCP) based on the voltage change of the circuit detected by the voltage detection unit (320). Then, the interval between zero crossing points can be detected as a half-cycle of the single-phase current flowing in the circuit. Then, based on the current amount detected during the half-cycle, the peak current amount and the average value of the high-frequency noise signal can be calculated.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] Meanwhile, if the zero crossing point is detected as a result of the detection by the voltage detection unit (320), the control unit (300) can start sampling the current and high-frequency noise signals until the next zero crossing point is detected. The current signals and high-frequency noise signals sampled in this manner may be the current amount and high-frequency noise signals for the half cycle.

[0078] Then, the control unit (300) can detect changes in the intensity of the high-frequency noise signal and changes in the current size, and determine whether the current change is within a critical range from the reference current (e.g., 0A) in the zero section based on the detection result. In addition, it can determine whether a fluctuation in high-frequency noise has occurred based on the detection result, and estimate whether high-frequency noise corresponding to arc occurrence has occurred based on a reference value determined based on the currently detected current amount.

[0079] And, if a half-cycle (hereinafter referred to as a half-cycle) of the single-phase current, which is estimated to include high-frequency noise corresponding to the occurrence of the arc, is detected more than a preset number of times during a preset time, it can be determined that an arc has occurred. And, a trip control signal for driving the blocking unit (350) so that the load is blocked from the power source can be output to the blocking unit (350).

[0080] In this case, the control unit (300) can perform a root mean square (RMS) calculation on the detected current samples to calculate the current amount for a half cycle. Then, at least one of the reference values ​​for arc detection can be determined based on the calculated current amount for a half cycle.

[0081] 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.

[0082] 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.

[0083] In order to solve this problem, the present invention, when an arc is estimated to have occurred in a circuit, firstly, it is regarded as noise and allowed to occur a certain number of times, and when a similar phenomenon occurs more than the certain number of times, it can be determined as an arc occurrence. In this case, since a series arc occurs continuously and periodically, the series arc can be distinguished from randomly occurring noise in that it occurs more than the certain number of times. In addition, the control unit (300) can determine that an arc has occurred when the arc-like phenomenon is detected even when the number of times the arc-like phenomenon is detected is more than the certain number of times. Hereinafter, 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.

[0084] Meanwhile, the greater the current during the half cycle, the greater the impact on the arc. 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 greater, so that even when the estimated number of arc occurrences is small, the electrical connection between the load and the power source can be cut off.

[0085] 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.

[0086] Meanwhile, the above allowable number of times can be set differently for each section depending on the effective current value during the half-cycle.

[0087] 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.

[0088] 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, an arc may be determined to have occurred only when it is estimated that an arc has occurred more than 18 and 20 times, respectively.

[0089] 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 (370) can store information on the root-mean-square current (hereinafter, the half-cycle current RMS) calculated from the samples acquired between ZCPs, that is, during the half-cycle, and various statistical values ​​calculated in relation to the half-cycle current RMS and the high-frequency noise signal, such as the average value or maximum value of the high-frequency noise signal.

[0090] 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.

[0091] 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 the current during the half cycle. In addition, the control unit (300) may detect fundamental components and harmonic components from the current 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] Meanwhile, the ZCT (340) is an example of a leakage current detection unit for detecting leakage current, and it is obvious that the present invention is not limited to having the ZCT (340) as a configuration for detecting leakage current. That is, in the arc monitoring device according to an embodiment of the present invention, any other leakage current detection unit capable of detecting leakage current can replace the ZCT (340).

[0096] 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.

[0097] 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.

[0098] 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).

[0099] 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, based on the ZCP, the current signal and the high-frequency noise signal are sampled according to a preset sampling interval for every half cycle of the AC current signal, so that the control unit (300) can obtain the current signal and the high-frequency current 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] And even if it is estimated that an arc has occurred in the circuit, the allowable number of times (or delay time) can be determined (S501).

[0105] 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 control unit (300) may set the allowable number of times to be small so that the occurrence of an arc can be determined more quickly as the current during the half cycle is large. On the other hand, the control unit (300) may set the allowable number of times to be large so that the occurrence of an arc can be determined more accurately as the current during the half cycle is small.

[0106] And 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 arc noise, which is a fluctuation in the zero section and high-frequency noise signal, has been detected (S502).

[0107] Here, the zero section refers to a time during which current does not flow due to insulation damage of the wire, and may refer to a time during which current within a preset range from a reference current (e.g., 0 A) flows during the half cycle. For example, referring to Fig. 4 (b) which illustrates a current flowing in a wire when an arc occurs, it can be seen that, except for an arc conduction state (413, 423) in which current is conducted due to a discharge phenomenon, sections in which current does not flow occur in a no-arc state (411, 421), an arc strike state (412, 422), and an arc quench state (414, 424). Here, a section in which current does not flow, that is, a section in which the current corresponds to 0 A, may be referred to as a zero section section, and an arc monitoring device according to an embodiment of the present invention may utilize this zero section section as an indicator for estimating whether an arc has occurred.

[0108] Meanwhile, even if insulation damage occurs, since the wire may not be completely disconnected, current conduction below a certain level may occur. In such a case, so that even if current conduction below the certain level occurs, it can be detected as a zero section, the control unit (300) sets a preset current range based on a reference current, i.e., 0 A, and if the currently acquired current sample has a current value included within the preset current range, it can be determined that the current sample corresponds to the zero section. In addition, based on the number of current samples corresponding to the zero section, it can be detected whether the half-cycle from which the current current sample is acquired includes a zero section.

[0109] Referring to FIGS. 6 to 8 below, the operation process for determining whether a zero section is detected in the half cycle in which the current current sample is acquired will be examined in more detail.

[0110] Meanwhile, in step S502, the control unit (300) can further determine whether the half-cycle in which the current current sample is acquired contains arc noise. In this case, the control unit (300) can compare the high-frequency noise during the half-cycle in which the current current sample is acquired with the high-frequency noise during the half-cycle acquired prior to the half-cycle and with the high-frequency noise during the half-cycle acquired prior to one cycle to detect whether a fluctuation in the high-frequency noise has occurred. If a fluctuation in the high-frequency noise has occurred, it can be determined that arc noise has occurred during the half-cycle in which the current current sample is acquired.

[0111] Referring to FIG. 9 below, the operation process for determining whether arc noise is detected in the half cycle in which the current current sample is acquired (hereinafter, the current half cycle) will be examined in more detail.

[0112] In step S502, if no zero section and arc noise are detected in the current half-cycle, the control unit (300) can initialize the arc check count calculated up to this point (S503). Then, the process proceeds to step S500 to acquire current samples and high-frequency noise samples for a new half-cycle. In this case, the event time count can be increased.

[0113] On the other hand, in step S502, if a zero section and arc noise 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 minimum current value (S504). In addition, if the current root mean square value during the current half cycle is lower than or equal to the minimum current 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 minimum current value, the resulting arc can also be so small that it can be ignored.

[0114] 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.

[0115] 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 an arc check is performed within a preset time for determining whether an arc occurs based on the current effective value during the half cycle.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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).

[0121] 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.

[0122] 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.

[0123] 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.

[0124] In this way, the operation process for determining whether high frequency noise corresponding to arc occurrence is included based on the high frequency noise average value during the current half cycle, the accumulated high frequency noise average value, and the arc check level will be examined in more detail with reference to FIG. 11.

[0125] 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.

[0126] 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).

[0127] 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.

[0128] On the other hand, if the comparison result of step S512 is that the arc check count 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).

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] Meanwhile, FIG. 6 is a flowchart illustrating an operation process for detecting whether a zero section has occurred during a half cycle of an AC current in an arc monitoring device according to an embodiment of the present invention. When step S502 of FIG. 5 is performed, the operation process of FIG. 6 described below may be performed to detect whether a zero section has occurred.

[0139] 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.

[0140] 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.

[0141] Referring to FIG. 6, the control unit (300) can first 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 (S600). 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.

[0142] When current samples corresponding to a reference current value (e.g., 0A) are extracted in the step S600, the control unit (300) can detect a preset number or more of consecutive samples among the extracted current samples (S602). 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 continuous for a preset number or more can correspond to a section in which a current corresponding to the reference current value is detected for a certain period of time or more, i.e., a zero section.

[0143] Accordingly, if, as a result of the detection in step S602, 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 the present (S606).

[0144] However, if, as a result of the detection in step S602, there are a preset number or more of consecutive samples among the current samples corresponding to the reference current value (e.g., 0 A), 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 (S604). Then, when the zero count is increased, the control unit can proceed to step S606 to check whether to enter the arc check cycle for checking whether an arc has occurred.

[0145] As a result of the check in step S606, 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 (S612). In this case, the zero section flag indicating whether or not the zero section has been detected may be maintained in the off state.

[0146] 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') (S614). If the event time count is initialized, the zero count accumulated up to the present can be initialized (S616). Therefore, when the event time count is initialized and a new cycle for determining whether an arc occurs begins, the zero count can be initialized. On the other hand, if the event time count is not initialized as a result of the check in step S614, the control unit (300) can end the operation process of FIG. 6 without initializing the zero count. Therefore, the zero count increased in step S604 can be maintained in an accumulated state. Then, when a current sample for another half cycle is acquired, the operation process of FIG. 6 is performed again, and the zero count can be increased and accumulated depending on the result of the determination of whether a zero section is included in step S602.

[0147] Meanwhile, if the result of the check in step S606 above shows that the event time count accumulated to date is greater than or equal to the count value corresponding to the preset threshold time, the control unit (300) can determine that the arc check cycle has been entered. Then, the control unit (300) can check whether the zero count accumulated to date has reached the preset zero count reference value (S608).

[0148] 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.

[0149] If the check result of the step S608 above shows that the accumulated zero count to date has not reached the preset zero count reference value, the control unit (300) may proceed to the step S612 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 S616 above and initialize the zero count based on the check result of the step S614 above.

[0150] On the other hand, if the check result of the step S608 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 (S610). 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 S616 above to initialize the zero count according to the check result of the step S614 above.

[0151] 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.

[0152] 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, in order to prevent misjudgment of whether a zero section is detected for arc detection due to this phase control, the 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. In addition, if it is determined in step S602 of FIG. 6 that a zero section section is included in the current half cycle, the zero count can be increased based on the discrete Fourier transform operation result. Accordingly, when the zero section increases according to the phase control, the zero count can be prevented from increasing.

[0153] Fig. 7 is a flowchart illustrating an operation process of increasing a zero count based on a harmonic ratio during the operation process of Fig. 6.

[0154] Referring to FIG. 7, if the detection result of step S602 during the operation process of FIG. 6 is that current samples corresponding to the reference current value (e.g., 0 A) that are consecutively greater than a preset number are detected, the control unit (300) can perform discrete Fourier transform on the current samples during the currently acquired half-cycle to analyze the frequency components of the current samples during the half-cycle (S700).

[0155] And when the frequency components are analyzed according to the analysis result of the above step S700, the control unit (300) can detect the fundamental component corresponding to the currently supplied AC current and the harmonic component for the fundamental component among the frequency components of the current samples during the half cycle. And the ratio of the harmonic component to the fundamental component, i.e., the harmonic ratio, can be calculated (S702).

[0156] When the harmonic ratio is calculated in the above step S702, the control unit (300) can check whether the calculated harmonic ratio is equal to or greater than a preset ratio (S704). In this case, if phase control is performed, such as the dimming, the harmonic component applied for the phase control can be detected, so that 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.

[0157] If the check result of step S704 above shows that 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, that is, step S606 of FIG. 6, without increasing the zero count. On the other hand, if the check result of step S704 above shows that 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, that is, arc generation. Therefore, the control unit (300) can increase the zero count (S706) and proceed to the next step, that is, step S606 of FIG. 6.

[0158] Meanwhile, in the aforementioned FIGS. 6 and 7, the presence or absence of a zero section was determined based on the current values ​​of current samples acquired during a half-cycle. However, when a zero section occurs due to an arc, the current samples whose current values ​​are close to the reference current, e.g., 0 A, increase, which may result in a decrease in the current amount (rms value). Accordingly, the presence or absence of a zero section can also be determined based on the change in the magnitude of the current amount (rms value).

[0159] FIG. 8 is a flowchart illustrating another operation process for detecting a zero section, which detects whether a zero section has occurred during the half cycle based on a change in the effective current value in an arc monitoring device according to an embodiment of the present invention. When step S502 of FIG. 5 is performed, the operation process of FIG. 8 described below may be performed to detect whether a zero section has occurred.

[0160] Referring to FIG. 8, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can first determine a zero count reference value for determining whether a zero section exists (S800). In this case, unlike the zero count reference value determined based on the magnitude of the half-cycle current amount (rms value) in FIG. 6, the zero count reference value can be determined based on the magnitude of high-frequency noise samples during the currently detected half-cycle.

[0161] In this case, the zero count reference value may be determined based on the minimum value of the high-frequency noise samples when the average value of the high-frequency noise samples is greater than or equal to a preset reference value. On the other hand, when the average value of the high-frequency noise samples is less than the preset reference value, the zero count reference value may be determined based on the average value of the high-frequency noise samples. Accordingly, the greater the average or minimum value of the high-frequency noise samples, the greater the zero count reference value may be set.

[0162] When the zero count reference value is determined in the above step S800, the control unit (300) can check whether the effective value of the currently calculated half-cycle current samples, i.e., the effective value of the half-cycle current amount, is less than or equal to the preset minimum current value (S802).

[0163] And if the check result of the step S802 is that the effective current value of a half-cycle exceeds the preset minimum current value, the control unit (300) can check whether the effective current value of the previous half-cycle, which is the effective value of the current samples obtained during the previous half-cycle, i.e., the half-cycle before the current half-cycle, is less than or equal to the preset minimum current value (S804). That is, if the effective current value of the current during the current half-cycle exceeds the minimum current value, it can be checked whether the effective current value of the previous half-cycle is less than or equal to the minimum current value, and whether the current has increased to exceed the preset minimum value since the previous half-cycle, i.e., during the current half-cycle.

[0164] And, if, as a result of the check in step S804, the current amount that was less than the minimum value during the previous half-cycle has increased to exceed the minimum value in the current half-cycle, the control unit (300) can determine that a sudden change in the current amount has occurred and increase the zero count for determining the zero section (S806).

[0165] Meanwhile, if the check result of step S802 shows that the effective current value of a half-cycle is less than or equal to the preset minimum current value, the control unit (300) can check whether the effective current value of the previous half-cycle, which is the effective value of current samples acquired during the previous half-cycle, i.e., the half-cycle before the current half-cycle, exceeds the preset minimum current value (S803). And if the check result of step S803 shows that the effective current value of the previous half-cycle exceeds the minimum current value, i.e., if the current exceeding the minimum value is reduced to less than or equal to the minimum value in the current half-cycle, the control unit (300) can determine that a sudden change in the current amount has occurred and increase the zero count for determining the zero section (S806).

[0166] And the control unit (300) can check whether the arc check cycle has been entered based on the event time count accumulated up to now (S808).

[0167] However, if the result of the check in step S804 is that the current amount of the previous half-cycle is greater than the minimum current value, that is, if the state in which the current amount exceeds the minimum current value is maintained as is, or if the result of the check in step 803 is that the current amount of the previous half-cycle is less than or equal to the minimum current value, that is, if the state in which the current amount is less than or equal to the minimum current value is maintained as is, the control unit (300) can determine that no sudden change in the current amount has occurred. Accordingly, the control unit can proceed to step S808 to determine whether the arc check cycle has been entered without increasing the zero count.

[0168] Meanwhile, if the check result of the above step S808 indicates that the arc check cycle has not been entered, the control unit (300) may determine that the zero section has not been detected regardless of the zero count (S814). In this case, the zero section flag indicating whether the zero section has been detected may remain in the off state.

[0169] Then, the control unit (300) can check whether the event time count has been initialized in step S516 of the above-mentioned FIG. 5 (S816). If the event time count has been initialized, the zero count accumulated to date can be initialized (S818). Accordingly, the event time count is initialized, and a new cycle for determining whether an arc has occurred begins, and the zero count can be initialized.

[0170] On the other hand, if the event time count is not initialized as a result of the check in step S816, the control unit (300) can end the operation process of FIG. 8 without initializing the zero count. Accordingly, the zero count increased in step S806 can be maintained in an accumulated state. Then, when a current sample for the next half cycle is acquired, the operation process of FIG. 8 is performed again, and the zero count can be increased and accumulated based on the result of comparing the root mean square values ​​of the current amounts for the current half cycle and the previous half cycle in steps S802 to S804.

[0171] Meanwhile, if it is determined as a result of the check in step S808 that the arc check cycle has been entered, the control unit (300) can check whether the zero count accumulated up to now has reached the zero count reference value determined in step S800 (S810).

[0172] And if the result of the check in step S810 indicates that the accumulated zero count up to now has not reached the zero count reference value, the control unit (300) may proceed to step S814 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. And, the control unit (300) may proceed to step S818 and initialize the zero count according to the result of the check in step S816.

[0173] On the other hand, if the check result of step S810 indicates that the accumulated zero count to date has reached the zero count reference value, the control unit (300) may determine that a zero section has been detected (S812). In this case, the zero section flag indicating whether a zero section has been detected may be switched on. Then, the control unit (300) may proceed to step S818 to initialize the zero count according to the check result of step S816.

[0174] Whether a zero section is detected can be determined in step S502 of FIG. 5 through the process described in FIGS. 6 to 7 or 8. Meanwhile, the control unit (300) of the arc monitoring device according to an embodiment of the present invention can proceed to step S504 of determining whether the current half-cycle current effective value exceeds a preset minimum value only when arc noise due to fluctuations in high-frequency noise is detected in step S502 of FIG. 5 in addition to the zero section.

[0175] FIG. 9 is a flowchart illustrating an operation process for determining whether arc noise is detected according to fluctuations in high-frequency noise in step S502 of FIG. 5. When step S502 of FIG. 5 is performed, the operation process of FIG. 9 described below may be performed to detect whether arc noise has occurred.

[0176] Referring to FIG. 9, 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 prior to one cycle from the current half-cycle, that is, a half-cycle detected prior to a time corresponding to two half-cycles including the current half-cycle (hereinafter, “half-cycle prior to one cycle”) (S900). 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 (S902).

[0177] 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.

[0178] 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 (S904).

[0179] In the above step S904, 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 (S906).

[0180] 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 (S907).

[0181] 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 S907 step may be omitted and the arc noise count may not be increased.

[0182] 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 (S908).

[0183] 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 (S910).

[0184] 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 S908 step may be omitted and the arc noise count may not be increased.

[0185] Therefore, if the average change in high-frequency noise during a half cycle or the maximum change in high-frequency noise during one cycle is less than or equal to a preset reference value in step S906, the arc noise may not increase. In addition, if the arc noise has not increased, step S908 may be entered, and it may be checked whether 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 addition, if the check result of step S908 shows that the average change in high-frequency noise during a half cycle or the maximum change in high-frequency noise during one cycle is less than or equal to a preset reference value, the arc noise may not increase.

[0186] On the other hand, 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 exceeds a preset reference value in step S906, the control unit (300) may proceed to step S907 to increase the arc noise. If the check result of step S908 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 again exceeds a preset reference value, the control unit (300) may proceed to step S910 to increase the arc noise again. That is, the arc noise may increase up to two times in steps S907 and S910.

[0187] And the control unit (300) can determine an arc noise count reference value for arc noise detection based on the accumulated arc noise count (S912). 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 period 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) 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.

[0188] Meanwhile, when the arc noise count reference value is determined in step S912, the control unit (300) can check whether the arc noise count accumulated up to now has reached the determined arc noise count reference value (S914).

[0189] And if the result of the check in step S914 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 S915 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 the off state. Then, the control unit (300) may check whether the event time count has been initialized in step S516 of FIG. 5 (S918). And if the event time count has been initialized, the arc noise count accumulated up to now may be initialized (S920). 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.

[0190] On the other hand, if the event time count is not initialized as a result of the check in step S918, the control unit (300) can end the operation process of FIG. 9 without initializing the arc noise count. Accordingly, the accumulated state of the arc noise count increased in steps S907 and S910 can be maintained. Then, when a current sample for the next half cycle is acquired, the operation process of FIG. 9 is performed again, and the arc noise count can be increased and accumulated up to two times according to the check results in steps S906 and S908.

[0191] On the other hand, if the check result of the step S914 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 (S916). 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 S920 above to initialize the arc noise count according to the check result of the step S918 above.

[0192] Meanwhile, in the above Fig. 9, it was explained that the arc noise count increases based on the fluctuation amount of the average value and maximum value of the high-frequency noise, but if the fluctuation amount 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 before one cycle, the increase in the arc noise count may be accelerated. Fig. 10 is a flowchart illustrating an operation process in which the accumulation of the arc noise count is accelerated based on whether or not the current amount fluctuates.

[0193] Referring to FIG. 10, the control unit (300) proceeds to step S910 of FIG. 9 and if the arc noise count increases, or if the average change value of high-frequency noise for one cycle or the maximum change value of high-frequency noise for half a cycle is lower than or equal to a preset reference value as a result of the check in step S908, the control unit (300) can detect the root mean square (RMS) current for the previous half cycle and the root mean square (RMS) current for the half cycle prior to one cycle (S1000). Here, the memory (370) of the arc monitoring device according to an embodiment of the present invention stores data for detecting whether an arc has occurred whenever the operation process of FIG. 5 for each half cycle ends, and the root mean square (RMS) current for the half cycle prior to one cycle and the root mean square (RMS) current for the previous half cycle may be pre-stored in the memory (370).

[0194] If the root mean square root of current during the previous half cycle and the root mean square root of current during the half cycle preceding one cycle are detected in step S1000, the control unit (300) can determine whether the currently calculated root mean square root of current during the half cycle is less than or equal to a preset minimum value (S1002). If the determination result shows that the currently calculated root mean square root of current during the half cycle preceding one cycle is less than or equal to a preset minimum value, the control unit (300) can determine whether the detected root mean square root of current during the half cycle preceding one cycle exceeds the preset minimum value (S1004). In other words, it can be determined whether the current during the current half cycle has decreased to less than or equal to the minimum value compared to the current during the half cycle preceding one cycle.

[0195] And if the determination result of the step S1004 is that the effective current value for the half cycle prior to the detected one cycle exceeds the minimum value, the control unit (300) can increase the arc noise count (S1008). Therefore, if the arc noise count is increased in the steps S907 and S910 of FIG. 9 and the arc noise count is further increased through the step S1008, the arc noise count can be increased three times. That is, the arc noise count can be increased up to three times.

[0196] However, if the determination result of the step S1004 above shows that the effective current value for the half cycle prior to the detected one cycle is less than the minimum value, that is, if both the current for the current half cycle and the current for the half cycle prior to the one cycle are less than the preset minimum value, the control unit (300) can determine that there is no change in the current amount. Accordingly, the arc noise count reference value can be calculated based on the critical time for determining the arc check cycle without increasing the arc noise count (S1010). Then, the process can proceed to step S914 of FIG. 9.

[0197] Meanwhile, if the current effective value for the currently calculated half-cycle as a result of the determination in step S1002 exceeds the preset minimum value, it can be determined whether the current effective value for the half-cycle prior to the detected one cycle is less than or equal to the minimum value (S1006). In other words, it can be determined whether the current for the current half-cycle increases and exceeds the minimum value while the current for the half-cycle prior to the one cycle has the minimum value.

[0198] And if the determination result of step S1006 is that the root mean square (RMS) current during the half cycle prior to the detected one cycle is less than the minimum value, the control unit (300) may proceed to step S1008 to increase the arc noise count. However, if the determination result of step S1006 is that the root mean square (RMS) current during the half cycle prior to the detected one cycle exceeds the minimum value, that is, if both the current during the current half cycle and the current during the half cycle prior to the one cycle are equal to or greater than the preset minimum value, the control unit (300) may determine that there is no change in the current amount. Therefore, without increasing the arc noise count, the control unit may proceed to step S1010 to calculate the arc noise count reference value according to the critical time for determining the arc check cycle. And the control unit may proceed to step S914 of FIG. 9.

[0199] Meanwhile, Fig. 11 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 is performed, the operation process of Fig. 11 described below may be performed to detect high-frequency noise corresponding to the arc occurrence.

[0200] Referring to FIG. 11, the control unit (300) can first calculate the average of the high-frequency noise samples collected during the current half-cycle (S1100). Then, the control unit can calculate the cumulative average of the high-frequency noise samples collected for each half-cycle prior to the current half-cycle (S1102). 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 was initialized.

[0201] Alternatively, it may be a cumulative average of high-frequency noise samples collected during each half-cycle detected over a preset period. In this case, the cumulative high-frequency noise average may be an average of high-frequency noise typically detected in a wire on which arc monitoring is performed in an arc monitoring device according to an embodiment of the present invention.

[0202] 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 (S1104).

[0203] 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.

[0204] 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.

[0205] When the arc check level is determined in the step S1104, 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 (S1106). In this case, the accumulated arc check level can be determined according to a certain ratio of the arc check level determined in the step S1104. That is, the accumulated arc check level does not exceed the arc check level determined in the step S1104, 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.

[0206] 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 S1100 with the high-frequency noise value according to the arc check level calculated in step S1104 (S1108).

[0207] 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.

[0208] Accordingly, if the comparison result of step S1108 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 (S1114). 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.

[0209] Meanwhile, if the comparison result of the step S1108 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 S1102 exceeds the high-frequency noise value according to the cumulative arc check level determined in the step S1106 (S1110).

[0210] And if the result of the check in step S1110 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 S1114 to 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.

[0211] On the other hand, if the result of the check in step S1110 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 half-cycle in which the current high-frequency noise sample is collected includes high-frequency noise corresponding to arc occurrence (S1112). In this case, the arc check level flag indicating whether the high-frequency noise corresponding to the arc occurrence 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.

[0212] 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 From the above voltage change, the zero crossing point, which is the point in time when the reference voltage is detected according to the phase shift of the voltage, is detected and 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 corresponding to the zero crossing point and a zero crossing point, and an arc noise according to the amount of fluctuation of a high-frequency signal are detected. When the above zero section and arc noise are detected, it is estimated whether an arc (ARC) occurs during the half cycle based on the average intensity of the high-frequency signal. Determine whether an arc has occurred in the circuit based on whether the estimated number of arc occurrences is greater than the preset allowable number; and A control unit that controls the blocking unit to block the circuit based on the determination result. An arc monitoring device characterized by including:

2. In the first paragraph, 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 critical 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.

3. In the second paragraph, the control unit, An arc monitoring device characterized in that, when 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, and the zero section is re-estimated according to the ratio of the fundamental wave and the harmonic wave detected as a result of the frequency component analysis.

4. In paragraph 1, the control unit, An arc monitoring device characterized in that, if neither the zero section nor the arc noise is detected as a result of the detection of the above zero section and arc noise, the number of arc occurrences estimated up to now is initialized.

5. In the first paragraph, the control unit, Calculate the root mean square (RMS) values ​​of the current values ​​detected during the half cycle of the above current, and determine the allowable number of times based on the calculated root mean square (RMS) value. 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.

6. In paragraph 5, the control unit, An arc monitoring device characterized in that when both the above zero section and arc noise are detected, the number of arc occurrences estimated up to now is initialized if the calculated effective value does not exceed a preset minimum value.

7. In paragraph 6, the control unit, By comparing the calculated root mean square root value with the calculated root mean square root value during the half cycle preceding the half cycle of the current, a change in the current magnitude during the half cycle of the current is detected, and a zero section is estimated from current samples acquired during the half cycle according to the detected change in the current magnitude. 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.

8. In the first paragraph, the control unit, When both the above zero section and arc noise are detected, it is determined whether the half-cycle of the current has entered the arc check period for detecting whether an arc has occurred within the critical period determined by the preset number of 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.

9. In paragraph 8, the control unit, When the above zero crossing point is detected, the event time count for counting the time elapsed during the critical period is increased, An arc monitoring device characterized in that it is determined that the arc check cycle has been entered when the increased event time count reaches a preset number.

10. In paragraph 9, the control unit, When the above event time count reaches a preset number of half-cycles corresponding to the above threshold period, the above event time count is initialized, An arc monitoring device characterized in that the number of arc estimates counted before the critical period is deducted from the number of arc estimates accumulated to date.

11. In the first paragraph, the control unit, Calculate the average and maximum values ​​of the high-frequency signals detected during the half-cycle of the above current, and The calculated average value and maximum value are compared with the average value and maximum value of the high-frequency signal detected during the half cycle preceding the half cycle of the current, and the average value and maximum value of the high-frequency signal detected during the half cycle preceding one cycle from the half cycle of the current, thereby calculating the high-frequency signal fluctuation value during the half cycle and the high-frequency signal fluctuation value during one cycle. Based on the results of comparing the high-frequency signal fluctuation value during the above-mentioned half-cycle and the high-frequency signal fluctuation value during the above-mentioned one-cycle with the preset high-frequency signal minimum value, the arc noise count is increased by at least one to estimate whether arc noise has occurred. An arc monitoring device characterized in that it is estimated that the arc noise has occurred when the increased arc noise count is greater than a preset arc noise reference value.

12. In the 11th paragraph, the control unit, An arc monitoring device characterized in that it determines whether the root mean square values ​​of current values ​​have changed based on the root mean square values ​​of current values ​​detected during the half cycle of the current and the root mean square values ​​of current values ​​detected during the half cycle prior to one cycle, and additionally increases the arc noise count when the root mean square values ​​of current values ​​have changed.

13. In the first paragraph, the control unit, An arc monitoring device characterized in that the zero crossing point detected according to the voltage change of the voltage detection unit is input as an interrupt signal, and sampling of a current signal and a high-frequency signal begins when the interrupt signal is received.

14. The first step is to detect the zero crossing point, which is the point in time at which the reference voltage is obtained according to the voltage change of the current flowing in the circuit; A second step of sampling the current signal and high-frequency signal during a half cycle of the current between the detected zero crossing point and the zero crossing point when the zero crossing point is detected; A third step is to increment the event time count to check the elapsed time; A fourth step of detecting whether a zero section exists based on the time at which a current value within a threshold range from a reference current is detected based on current samples acquired during the half cycle of the current; A fifth step of detecting arc noise according to the amount of fluctuation of a high-frequency signal based on high-frequency signal samples acquired during the half cycle of the above current; A sixth step of estimating whether an arc (ARC) occurs during the half cycle based on the average intensity of the high-frequency signal when the above zero section and arc noise are detected; Step 7: If arc occurrence is estimated, the estimated number of arc occurrences is increased, and whether the number of arc occurrences accumulated to date is greater than the preset allowable number is checked; An eighth 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 ninth step of checking whether the accumulated event time count has reached a preset number of half-cycles corresponding to a preset threshold cycle when the accumulated number of arc occurrences is less than the allowable number; and A control method for an arc monitoring device, characterized in that it includes a tenth step of initializing the event time count when the accumulated event time count reaches a preset number of half-cycles corresponding to the critical period.

15. In paragraph 14, The above 10th step is, It further includes a step 10-1 of deducting the number of times counted before a preset time from the above accumulated number of arc occurrences, The above preset time is, A control method of an arc monitoring device characterized in that the time corresponds to a preset number of half-cycles corresponding to the above critical period.

16. In paragraph 14, the fourth step is: Step 4-1 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 have been detected; and, A control method of an arc monitoring device, characterized in that it includes a step 4-2 of determining that the zero section is detected when the zero count value accumulated by the number of estimated zero sections for each half cycle reaches a preset zero count reference value.

17. In paragraph 16, the fourth step is: Step 4-3 of analyzing the frequency components of current values ​​detected during a half cycle of the current by performing a discrete Fourier transform when the above zero section is estimated; A control method for an arc monitoring device, characterized in that it further includes a 4-4 step 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.

18. In paragraph 14, the fourth step is: Step 4-5 of detecting a change in the current size during a half-cycle of the current by comparing the calculated effective value with the effective value of the current during a half-cycle prior to the half-cycle of the current; Steps 4-6 of estimating the zero section during the half cycle according to the detected current magnitude change; and A control method of an arc monitoring device, characterized in that it includes steps 4-7 of determining that the zero section is detected when the zero count value accumulated by the number of estimated zero sections for each half cycle reaches a preset zero count reference value.

19. In paragraph 14, the fifth step is: Step 5-1 of calculating the average and maximum values ​​of high-frequency signals detected during the half cycle of the above current; Step 5-2 of calculating the high-frequency signal fluctuation value during a half cycle and the high-frequency signal fluctuation value during one cycle by 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; Step 5-3 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 calculated 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 5-4 of estimating that the arc noise has occurred when the increased arc noise count is greater than a preset arc noise reference value.

20. In paragraph 19, the fifth step is: Step 5-5 of determining whether the root mean square values ​​of current values ​​have changed based on the root mean square values ​​of current values ​​detected during the half cycle of the current and the root mean square values ​​of current values ​​detected during the half cycle prior to one cycle; and A control method for an arc monitoring device, characterized in that it further includes a 5th to 6th step of additionally increasing the arc noise count when the effective value of the current values ​​changes.

21. In paragraph 14, the sixth step is: A control method of an arc monitoring device, characterized in that it includes a step 6-1 of initializing the number of arc occurrences estimated up to now if, as a result of detecting the zero section and arc noise, neither the zero section nor the arc noise is detected.

22. In paragraph 14, the second step is: Calculate the root mean square (RMS) values ​​of the current values ​​detected during the half cycle of the above current, and determine the allowable number of times based on the calculated root mean square (RMS) 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.

23. In paragraph 22, the sixth step is: A control method of an arc monitoring device, characterized in that it includes a step 6-2 of initializing the number of arc occurrences estimated up to now when both the above zero section and arc noise are detected and the calculated effective value does not exceed a preset minimum value.

24. In paragraph 14, the sixth step is, Step 6-3 of determining whether the event time count has entered the arc check period for detecting whether an arc has occurred within the threshold period, based on whether the event time count has reached the number of half-cycles corresponding to the preset threshold period, when both the zero section and the arc noise are detected; and A control method of an arc monitoring device, characterized in that it includes a step 6-4, characterized in that the estimated number of arc occurrences estimated up to now is deducted if the arc check period is not entered.

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