Arc detection device and device control method

Abstract

The present invention relates to an arc detection device comprising: a current detection unit for detecting current of an electric circuit; a high-frequency (HF) signal detection unit for detecting HF noise signals from the electric circuit; a first band detection unit for detecting HF noise signals of a first frequency band from among the detected HF noise signals; a second band detection unit for detecting HF noise signals of a second frequency band from among the detected HF noise signals; and a control unit for estimating, on the basis of the magnitude of the current detected from the electric circuit, the number of times a signal of a predetermined magnitude or more from among the noise signals detected from any one of the first and second frequency bands has been detected for a predetermined time, and the average intensity of the noise signals detected from the other one of the first and second frequency bands, whether an arc has occurred, determining whether an arc has occurred in the electric circuit by comparing the estimated number of times with a reference number of times, and controlling an interrupting unit such that the electric circuit is interrupted according to whether an arc has occurred.

Description

Arc detection device and control method of the device

[0001] The present invention relates to an arc detection device for detecting an arc and a method for controlling the device.

[0002] Generally, an arc refers to an electric spark or flame. It describes a discharge phenomenon that occurs when a high-voltage potential difference arises between positive and negative terminals, characterized by high current density. Such arcs are caused by damage to wires or electrical products, insulation breakdown, connection defects, or aging. Since they can lead to fires if flammable materials are present nearby, they are known as a primary cause of electrical fires.

[0003] Meanwhile, conventional earth leakage circuit breakers or overcurrent circuit breakers are primarily designed to prevent earth leakage or short circuits, and their tripping function can be activated when a current exceeding a preset magnitude is detected for a certain period of time. However, since arcs can occur even at low currents of 3 to 5 A or less, there is a problem in that arcs generated at such low currents are difficult to detect with earth leakage circuit breakers or overcurrent circuit breakers. Consequently, research to detect arcs is actively underway, with various countries mandating the installation of arc fault circuit breakers.

[0004] As part of this research, an arc detection device has emerged that detects noise in current signals and identifies the occurrence of an arc by utilizing the magnitude of the high-frequency component of the detected noise. However, such arc detection devices have limitations in distinguishing between ordinary current noise and arcs, and suffer from low precision, such as misidentifying noise as an arc or misjudging an arc as noise.

[0005] To address this problem, methods have emerged that involve setting a specific frequency band of interest for the noise generated during arc occurrence—namely, arc noise—and determining whether an arc has occurred by detecting the presence of noise within that band. However, this approach has a high probability of interference from other wireless signals using the aforementioned frequency band of interest, and there is a problem in that such interference can lead to the wireless signal being detected as an arc.

[0006] Furthermore, since the aforementioned arc noise takes the form of white noise occurring across a wide band rather than being concentrated in a specific band, there is a problem in that it is difficult to accurately detect whether an arc has occurred using the current method of detecting arcs based on the magnitude of arc noise occurring in a specific band of interest.

[0007] The present invention aims to solve the aforementioned problem by providing an arc detection device and a method thereof that can accurately determine whether an arc has occurred by accurately detecting arc noise having the form of white noise generated when an arc occurs.

[0008] According to one aspect of the present invention for achieving the above or other purposes, an arc detection device according to an embodiment of the present invention comprises: a current detection unit for detecting a current flowing in an electrical circuit; a high frequency signal detection unit for detecting a high frequency (HF) noise signal from the electrical circuit; a first band detection unit for detecting HF noise signals of a preset first frequency band among the detected HF noise signals; a second band detection unit for detecting HF noise signals of a second frequency band different from the first frequency band among the detected HF noise signals; and estimating whether an arc (ARC) has occurred based on the magnitude of the current detected from the electrical circuit during a preset time, the number of times a signal having a strength greater than or equal to a preset magnitude among noise signals detected from either the first frequency band or the second frequency band is detected during the preset time, and the average signal strength of noise signals detected from the other of the first frequency band and the second frequency band; determining whether an arc has occurred in the electrical circuit based on whether the number of times an arc has occurred is greater than or equal to a preset reference number, and according to the determined whether an arc has occurred, the electrical circuit It is characterized by including a control unit that controls the blocking unit to block.

[0009] In one embodiment, either of the first frequency band and the second frequency band is a low frequency band with a lower frequency band than the other, and the other of the first frequency band and the second frequency band is a high frequency band with a higher frequency band than either of the first.

[0010] In one embodiment, the low frequency band is a frequency band between the AM radio frequency band and the FM radio frequency band, and the high frequency band is a frequency band between the frequency band corresponding to channels 5 to 6 and the frequency band corresponding to channels 7 to 13 among the TV broadcast frequency bands of the VHF (Very High Frequency) band.

[0011] In one embodiment, the high frequency band is a frequency band with a center frequency of 150 MHz, and the low frequency band is a frequency band between 1 MHz and 2 MHz, or a frequency band where shortwave broadcasting takes place.

[0012] In one embodiment, either of the first band detection unit and the second band detection unit detects HF noise signals having a frequency included within the range of the preset frequency band through a band-pass filter that detects signals having a frequency included within the range of the preset frequency band, and the other of the first band detection unit and the second band detection unit detects HF noise signals matching the specific frequency band through a narrow-band matching filter that detects signals matching the specific frequency band.

[0013] In one embodiment, either the first band detection unit or the second band detection unit outputs a pulse signal having a preset value or a pulse signal not having the preset value to the control unit, depending on the result of comparing the signal strength of the detected HF noise signals with a preset reference voltage.

[0014] In one embodiment, the control unit counts the number of pulse signals having the preset value and counts the number of times a signal having a strength greater than or equal to a preset magnitude among the noise signals detected from either the first frequency band or the second frequency band is detected during the preset time.

[0015] In one embodiment, the preset time is a time corresponding to a half-cycle of the current flowing in the circuit, and the control unit is characterized by detecting a zero crossing point according to the phase alternation of the voltage detected from the voltage change of the circuit, and determining a time corresponding to a half-cycle of the current based on the detected zero crossing point.

[0016] In one embodiment, the control unit determines the reference number based on the magnitude of the peak current detected during the half-cycle of the current, and the reference number is determined to be smaller as the magnitude of the detected peak current increases.

[0017] In one embodiment, the first band detection unit is activated for a portion of the preset time and detects HF noise signals of the first frequency band during the activated time, the second band detection unit is activated for the remaining time excluding the portion of the preset time and detects HF noise signals of the second frequency band during the activated time, and the control unit determines the ratio of the time during which the first band detection unit is activated and the time during which the second band detection unit is activated according to the region where the arc detection device is placed.

[0018] In addition, a control method for an arc detection device according to an embodiment of the present invention comprises: a step of calculating a peak current for a predetermined period from a circuit through which current flows; a step of detecting, from the circuit during the predetermined period, HF (High Frequency) noise signals of a preset first frequency band and HF noise signals of a second frequency band different from the first frequency band; a step of calculating the average signal strength of noise signals detected from either the first frequency band or the second frequency band when the result of comparing the peak current with the preset reference current satisfies the arc generation condition according to the reference current; a step of counting the number of times a signal having a strength greater than or equal to a preset magnitude among the noise signals detected from the other of the first frequency band and the second frequency band is detected during the predetermined period when the result of comparing the calculated average signal strength with a preset reference value satisfies the arc generation condition according to the reference value; and, when the result of comparing the counted number with a preset reference number satisfies the arc generation condition according to the preset number satisfies the arc generation condition according to the reference number, increasing the arc count, and the accumulated arc count and the preset reference count The method is characterized by including a step of comparing, and a step of interrupting the circuit to cut off the electrical connection between the power source and the load when, as a result of comparing the accumulated arc count and the reference count, the arc generation conditions according to the reference count are satisfied.

[0019] In one embodiment, either of the first frequency band and the second frequency band is a high frequency band with a higher frequency band than the other, and the other of the first frequency band and the second frequency band is a low frequency band with a lower frequency band than either of the first.

[0020] In one embodiment, the step of counting the number of times a signal having a strength greater than or equal to a preset size is detected during the predetermined time period is characterized by comprising: a step of comparing the signal strength of HF noise signals detected from the other of the first frequency band and the second frequency band with a preset reference voltage; a step of generating a pulse signal having a preset value or a pulse signal not having the preset value according to the result of comparing the signal strength of the HF noise signals with the reference voltage; and a step of counting the number of pulse signals having the preset value to count the number of times a signal having a strength greater than or equal to a preset size is detected among the noise signals detected from the other of the first frequency band and the second frequency band during the predetermined time period.

[0021] In one embodiment, the step of detecting the peak current further includes the step of increasing an arc check time count to check whether a preset initialization time has been reached, and the steps of calculating the signal strength average, counting the number of times a signal having a strength greater than or equal to a preset magnitude is detected during a predetermined time, comparing the accumulated arc count with a preset reference count, and disconnecting the electrical connection between the power source and the load each further include the step of initializing the accumulated arc count according to whether the time according to the arc check time count has reached the initialization time when the arc occurrence condition is not satisfied.

[0022] In one embodiment, the step of initializing the accumulated arc count comprises: a step of detecting the number of at least one arc count that was counted prior to the initialization time among the accumulated arc counts; and a step of initializing at least a portion of the accumulated arc count according to the number of at least one arc count detected.

[0023] In one embodiment, the fixed time is characterized as a time corresponding to a half-cycle of the current flowing through the current, and is a time that varies according to the frequency of the current flowing through the circuit.

[0024] In one embodiment, the step of calculating the peak current further includes the step of determining the reference number according to the magnitude of the peak current calculated during the predetermined time period, wherein the reference number is determined to be smaller as the magnitude of the detected peak current increases.

[0025] The effects of the arc detection device and the arc detection device control method according to the present invention are described as follows.

[0026] According to at least one embodiment of the present invention, the present invention detects HF noise in a preset high-frequency band and HF noise in a low-frequency band, and detects arc noise occurring in a wide frequency band extending from the high-frequency band to the low-frequency band by detecting the HF noise in the high-frequency band and the HF noise in the low-frequency band. Accordingly, there is an effect of being able to detect arc noise having white noise characteristics more accurately.

[0027] In addition, the present invention enables the detection of HF noise in a specific frequency band where the least mutual interference occurs among a plurality of TV broadcast frequency bands as HF noise in the high frequency band for arc detection, and the detection of HF noise in a specific frequency band where the least mutual interference occurs among a plurality of radio broadcast frequency bands as HF noise in the low frequency band for arc detection. Accordingly, by minimizing interference caused by other radio frequencies, the arc noise can be detected more accurately.

[0028] In addition, the present invention enables the detection of HF noise corresponding to arc generation by detecting at least one of the HF noise in the high-frequency band or the HF noise in the low-frequency band as a pulse signal and counting the generated pulse signal. Accordingly, even if interference occurs due to a wireless signal in an adjacent frequency band, it is counted as a single pulse signal and the influence according to its intensity is excluded, thereby having the effect of minimizing interference due to other wireless signals in an adjacent frequency band.

[0029] Figure 1 is a conceptual diagram to explain the types of arcs according to the cause of occurrence.

[0030] Figure 2 is an example diagram showing an example of arc noise having the characteristics of white noise.

[0031] Figure 3 is a diagram showing typical high-frequency arc noise and current change during arc generation.

[0032] FIG. 4 is a block diagram illustrating the configuration of an arc detection device according to an embodiment of the present invention.

[0033] Figure 5 is an illustrative diagram showing examples of frequency spectra for frequencies of other commonly used wireless signals.

[0034] FIGS. 6a and FIGS. 6b are block diagrams illustrating the structure of an arc detection device according to an embodiment of the present invention, which detects arc noise based on signals of the high-frequency HF noise and low-frequency HF noise bands determined in FIG. 5.

[0035] FIG. 7 is a flowchart illustrating the operation process of determining whether an arc has occurred based on the detection results of high-frequency HF noise signals and low-frequency HF noise signals in an arc detection device according to an embodiment of the present invention.

[0036] FIG. 8 is a block diagram illustrating the configuration of an arc detection device according to another embodiment of the present invention.

[0037] It should be noted that technical terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Additionally, singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. The suffixes "module" and "part" for components used in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not inherently possess distinct meanings or roles.

[0038] In this specification, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as potentially excluding some of the components or steps, or including additional components or steps.

[0039] In addition, when describing the technology disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the technology disclosed in this specification, such detailed description is omitted.

[0040] In addition, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that they include all modifications, equivalents, and substitutions that fall within the concept and technical scope of the present invention. Furthermore, not only each of the embodiments described below, but also combinations of embodiments may fall within the concept and technical scope of the present invention as modifications, equivalents, and substitutions that fall within the concept and technical scope of the present invention.

[0041] First, Figure 1 is a conceptual diagram to explain the types of arcs according to the cause of occurrence.

[0042] Referring to FIG. 1, FIG. 1 illustrates 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 generated 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 using a gas as a conductive medium when at least a part of the wire is disconnected. In other words, an arc can be defined as a state in which at least a part of the wire is disconnected but current can still be conducted due to an electrical discharge.

[0043] In cases where only a part of the circuit is disconnected, or even if it is disconnected, current can be conducted through a gas medium, electrical energy from the power source can be supplied to the load through the part that is not disconnected or through the gas that serves as the current medium. However, when current flows through a gas medium, there is a risk that an electrical fire may occur because air discharge of electrical energy occurs in the surroundings.

[0044] Meanwhile, such arcs can occur in each circuit due to individual causes. 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, an arc may occur in only one of the live line or the neutral line, as shown in Fig. 1 (a), or an arc may occur in all circuits, that is, in both the live line and the neutral line, as shown in Fig. 1 (b).

[0045] For example, in cases such as aging or deterioration of the circuit, an arc may occur in only one of the live wires or the neutral wire, as shown in Figure 1 (a). An arc that occurs in only one circuit in this manner will be referred to as a series arc below.

[0046] On the other hand, as shown in (b) of FIG. 1, an arc can occur in both the live line and the neutral line. For example, if strong physical pressure from heavy equipment is applied to both circuits, physical damage may occur to both circuits, and due to this physical damage, an arc may occur in both circuits. An arc that occurs when both circuits are short-circuited in this way is referred to as a parallel arc, unlike the series arc mentioned above.

[0047] Meanwhile, a noise signal including conventional noise, such as switching noise (211), has the characteristic that its magnitude decreases as the frequency increases, as shown in the noise signal (210) in FIG. 2. However, noise generated during arc generation, i.e., arc noise, has the characteristic of occurring in the form of white noise that occurs evenly across a wide frequency band ranging from several MHz to several hundred MHz, as shown in the arc noise signal (200) in FIG. 2.

[0048] Meanwhile, FIG. 3 is a diagram showing typical high-frequency arc noise and current changes during arc generation. In FIG. 3, (a) is an example diagram showing the characteristics of high-frequency arc noise, and (b) is a diagram showing current changes according to the periodic pattern of the arc.

[0049] First, referring to FIG. 3(a), when the current characteristics of the alternating current are close to the point where the voltage crosses from positive to negative, that is, the zero crossing point, the voltage difference between adjacent arc contacts may decrease. Therefore, an arc may not occur. In this stage where no arc occurs between arc contacts, i.e., the no-arc stage (311), high-frequency noise signals may not be detected as no arc occurs.

[0050] However, depending on the characteristics of the alternating current, the voltage supplied may gradually increase as it passes the zero crossing point. Then, the voltage difference between the contacts may gradually increase. And when the voltage difference between the contacts exceeds a certain level, a discharge, i.e., an arc, may occur due to the accumulated voltage difference. Therefore, as it passes the no-arc stage (311) corresponding to the zero crossing point, an arc strike stage (312) may proceed in which an arc is formed due to the increase in voltage difference and the strength and magnitude of the high-frequency noise signal increase.

[0051] Meanwhile, when the voltage difference between the two contacts increases further and reaches a voltage level capable of conducting current through the gas, a discharge phenomenon, i.e., current conduction, can occur between the contacts on both sides of the disconnected circuit. In this case, as current is conducted between the arc contacts, the intensity of the arc noise signal can gradually decrease from its maximum value (arc conduct stage (313)).

[0052] Additionally, in the arc conduct step (313), if the voltage decreases again according to the characteristics of the alternating current, a voltage of sufficient magnitude to conduct current may not be formed between the two contacts. Then, current conduction is interrupted again, and the current flowing to the other contact may be switched back to an arc. Accordingly, a phenomenon in which the strength of the arc noise signal increases again (arc quench step (314)) may proceed.

[0053] Meanwhile, when the arc quench stage (414) is reached, the voltage may be further reduced according to the characteristics of the alternating current. And when the reduced voltage approaches the zero crossing point, the voltage difference between the two disconnected contacts may again approach zero. Then, the no-arc stage (321), in which no arc occurs, can be performed again.

[0054] When examining the change in current magnitude at each stage of the arc, in the no-arc stage (311, 321), arc strike stage (312, 322), and arc quench stage (314, 324), the voltage between the contacts is insufficient for current to be conducted through the gas. Therefore, the current flowing between the contacts may be limited during the no-arc stage (311, 321), arc strike stage (312, 322), and arc quench stage (314, 324). However, in the arc conduct stage (313, 323), current is conducted through the gas due to the sufficiently high voltage, so the current flow may increase rapidly during the arc conduct stage (313, 323). In this case, the increased current may become the maximum current flowing in the circuit during the half-cycle of the alternating current, i.e., the peak current.

[0055] Meanwhile, FIG. 4 is a block diagram illustrating the configuration of an arc detection device according to an embodiment of the present invention.

[0056] Referring to FIG. 4, an arc detection device according to an embodiment of the present invention may be configured to include a blocking unit (450), a current detection unit (410), an HFCT (400), a high-frequency band detection unit (410), a low-frequency band detection unit (420), a control unit (490), a communication unit (460), a memory (470), and an output unit (480). It may also be configured to include a ZCT (440) and a voltage detection unit (not shown) for detecting the voltage of a circuit connecting a power source and a load.

[0057] The components illustrated in FIG. 4 are not essential for implementing an arc detection device, so the arc detection device described herein may have more or fewer components than those listed above. Additionally, each component of the arc detection device illustrated in FIG. 4 may be connected to a control unit (400) and may be controlled by the control unit (400).

[0058] First, the blocking unit (450) can cut off the electrical connection between the power source and the load when it is determined that an arc has occurred or that a leakage current has occurred.

[0059] The above-mentioned blocking unit (450) may include a trip coil and a driving circuit for driving the trip coil, and the driving circuit may be driven according to a trip control signal provided by the control unit (400). That is, the blocking unit (450) may be driven according to a trip control signal provided by the control unit (400) to perform a blocking operation that cuts off the connection between the load and the power source.

[0060] The current detection unit (410) can detect the amount of current flowing in the circuit connecting the power source and the load. The current detection unit (410) may include a pre-set shunt resistor or an LFCT (Low Frequency Current Transformer), etc., to detect the amount of current. In this case, the current detection unit (410) may detect the amount of current based on a resistance detected through the shunt resistor or a low-frequency current signal detected by the LFCT. Additionally, the current detection unit (410) may be equipped with a LPF (Low Pass Filter) to remove noise from the measurement result and may further include an amplifier to amplify the measurement value to a level recognizable by the control unit (400).

[0061] Here, a bimetal component used in an arc detection device according to an embodiment of the present invention may be used as the shunt resistor. For example, a bimetal component used in the arc detection device may be used as the shunt resistor. In this case, the current detection unit (410) can detect the amount of current flowing in the circuit based on the intrinsic resistance value of the bimetal component. In this case, a separate shunt resistor may not be provided.

[0062] Meanwhile, an arc detection device according to an embodiment of the present invention may be configured to include a voltage detection unit (not shown) for detecting voltage changes in a circuit. In this case, if the current flowing in the circuit is a single-phase current, the current flowing between the power line and the internal line may be an alternating current in which the voltage phase periodically alternates according to the period of the single-phase current. Accordingly, in the circuit, positive (+) voltage and negative (-) voltage may periodically alternate around the ZCP. That is, the control unit (400) can detect the ZCP based on the voltage change of the circuit detected by the voltage detection unit.

[0063] Meanwhile, the HFCT (400) is a sensor for detecting HF (High Frequency) noise signals from the circuit and can be formed to pass through any one of the circuits. The HFCT (400) may include at least one sensor for detecting noise signals in a wide high frequency band ranging from several MHz to several hundred MHz that occur when partial discharge or arc occurs.

[0064] Here, the HFCT (400) may further include a filter that filters specific frequencies using a frequency mask method. Here, the specific frequency may be a frequency corresponding to everyday noise, noise generated during the operation of a load, or electromagnetic noise (EMC (ElectroMagnetic Compatibility) Noise). The filter may be a filter that passes signals in a high-frequency band, or a filter that prevents signals of at least one specific frequency band from passing through. Through this, not only signals in a low-frequency band but also noise with a known frequency band, such as everyday noise, noise from the operation of a load, or electromagnetic noise, can be removed.

[0065] Meanwhile, the arc detection device according to an embodiment of the present invention may be equipped with detection units (410, 420) for detecting HF noise signals detected in different frequency bands that are preset among the HF noise signals detected by the HFCT (400).

[0066] Among the above detection units (410, 420), the high-frequency band detection unit (410) can detect HF noise signals having a frequency higher than a certain frequency among the HF noise signals detected by the HFCT (400). On the other hand, the low-frequency band detection unit (420) can detect HF noise signals having a frequency lower than a certain frequency among the HF noise signals detected by the HFCT (400). That is, the HF noise signals detected by the high-frequency band detection unit (410) may be HF noise signals having a higher frequency than the HF noise signals detected by the low-frequency band detection unit (420).

[0067] Among the HF noise signals detected by the arc detection device according to an embodiment of the present invention for arc detection, HF noise signals having a relatively high frequency are referred to as high-frequency band HF noise signals, and HF noise signals having a relatively low frequency are referred to as low-frequency band HF noise signals.

[0068] Meanwhile, as shown in FIG. 4, the arc detection device according to an embodiment of the present invention can detect, through the high frequency band detection unit (410) and the low frequency band detection unit (420), HF noise signals detected through the HFCT (400), HF noise signals of a higher frequency band (high frequency band HF noise signal) and HF noise signals of a lower frequency band (low frequency band HF noise signal), respectively.

[0069] And the control unit (490) controls each component of the arc detection device and can control the overall operation of the arc detection device.

[0070] The control unit (490) can determine whether an arc has occurred in the circuit based on HF noise signals of different frequency bands detected by the high-frequency band detection unit (410) and the low-frequency band detection unit (420). For example, the control unit (490) can determine that an arc has occurred if the high-frequency band HF noise signal and the low-frequency band HF noise signal satisfy preset conditions for a certain period of time or longer. Then, it can output a trip control signal to the blocking unit (450) to drive the blocking unit (450).

[0071] To this end, the control unit (490) may start sampling current and high-frequency noise signals during half a cycle of the current flowing in the circuit. Then, based on the sampled current amount, the peak current amount during said half cycle may be calculated. And if the calculated peak current amount exceeds a preset reference current amount, it may be determined that it meets the preset first arc generation condition.

[0072] Meanwhile, the control unit (490) can determine a reference time for determining whether an arc has occurred based on the calculated peak current amount. In this case, the reference time may be a certain time for determining whether an arc has occurred based on the HF noise signal in the high frequency band and the HF noise signal in the low frequency band. And the control unit (490) can determine the value of a time count, i.e., a reference count, for determining whether an arc has occurred based on the length of the determined reference time.

[0073] In this case, the larger the peak current, the greater the amount of electricity discharged by the arc. Consequently, the risk of fire may increase. Therefore, the control unit (490) may determine a lower value for the reference count as the peak current increases, so that the electrical connection between the load and the power source can be cut off even when the number of times the preset arc occurrence condition is satisfied is low. In this case, whether an arc has occurred can be determined within a shorter time.

[0074] On the other hand, the smaller the peak current, the less electricity is discharged by the arc. Consequently, the risk of fire or other hazards may be lower. However, if the power supply between the load and the power source is interrupted, the load cannot receive electrical energy, which may result in unexpected damage to the user. Therefore, the value of the aforementioned reference count can be set higher so that the occurrence of an arc can be determined more accurately as the peak current decreases.

[0075] Meanwhile, the half-cycle of the current can be detected based on a zero-crossing point detected from a voltage change of the circuit. The control unit (490) can determine the period from when a zero-crossing point is detected until the next zero-crossing point is detected as the half-cycle of the current. That is, when a zero-crossing point is detected, the control unit (490) can detect that the previous half-cycle has elapsed and a new half-cycle has started.

[0076] In this case, the control unit (490) can calculate the peak current amount during the previous half-cycle by performing an RMS (Root Mean Square) calculation on the current samples detected from the time before the zero crossing point was detected until the time when the current zero crossing point is detected. The control unit (490) can then check whether the calculated peak current amount exceeds a preset reference current amount. Based on the check result, it can be determined that it meets the preset first arc generation condition.

[0077] Additionally, the control unit (490) can determine whether an arc has occurred based on high-frequency band HF noise signals and low-frequency band HF noise signals sampled from the HFCT (400) during the previous half-cycle.

[0078] To this end, the control unit (490) can check whether the average value of at least one of the high-frequency band HF noise signal samples and the low-frequency band HF noise signal samples exceeds a preset reference value based on the detection results of the high-frequency band detection unit (410) and the low-frequency band detection unit (420). And based on the check result, it can be determined that it meets the preset second arc generation condition.

[0079] Additionally, the control unit (490) can check whether a sample having a size greater than a preset size has been detected more than a preset number of times in at least one of the HF noise signal samples and the low-frequency band HF noise signal samples based on the detection results of the high-frequency band detection unit (410) and the low-frequency band detection unit (420). And based on the check result, it can be determined that it meets the preset third arc generation condition.

[0080] And the control unit (490) can determine whether an arc occurs based on whether a plurality of preset arc occurrence conditions (first to third arc occurrence conditions) are satisfied. More specifically, the control unit (490) can determine whether an arc occurs based on whether a sample having an intensity greater than the preset size is detected more than a preset number of times from at least one of the high-frequency band HF noise signal samples and the low-frequency band HF noise signal samples when the peak current amount exceeds the reference current amount, and whether the average value of the signal samples exceeds the preset reference value.

[0081] Here, the HF noise signals that check whether a sample having a size greater than the preset size has been detected more than a preset number of times may be low-frequency band HF noise signals. In this case, the low-frequency band detection unit (420) may output signals having different values ​​for cases where the HF noise signal samples of the preset first frequency band detected by the HFCT (400) have a size greater than the preset size and cases where they do not.

[0082] Accordingly, the low frequency band detector (420) can output a signal having a preset value if the detected HF noise signal sample in the low frequency band has a strength greater than or equal to a preset strength. On the other hand, if the detected HF noise signal sample in the low frequency band has a strength less than or equal to a preset strength, it can output a signal that does not have a preset value. Therefore, since signals consisting of signals having a preset value or signals not having a preset value are sequentially output from the low frequency band detector (420), the detection result of the HF noise signals in the low frequency band output from the low frequency band detector (420) can have the form of a pulse signal consisting of signals having or not having a preset value.

[0083] Then, the control unit (490) receives the detection result in the form of the pulse signal and can count the number of signals having the preset value from the received pulse signal. Accordingly, the control unit (490) can check whether a signal having a preset intensity or higher among the detected low-frequency band HF noise signals has been detected more than a preset number of times. And if the number of detected times is more than the preset number, it can be determined that it meets the third arc generation condition.

[0084] In this way, by outputting a signal with a preset value based on whether the strength of the sampled signal is greater than or equal to a preset strength, and counting the number of signals with the preset value among the output signals, only the number of times a signal is detected can be checked regardless of the signal strength. Therefore, even if the strength of a specific signal is very strong, it can be counted as only one signal. Consequently, interference from other wireless signals, such as signal strength increases caused by other wireless signals, can be minimized.

[0085] Meanwhile, as described above, when checking whether signals having a preset magnitude or larger than a preset number of times are detected for low-frequency band HF noise signals, the control unit (490) can determine whether an arc generation condition (second arc generation condition) is satisfied according to the average value of the signal strengths for other frequency bands, i.e., high-frequency band HF noise signals.

[0086] In this case, the control unit (490) can calculate the average intensity of HF noise signal samples of a preset high frequency band detected during the half-cycle of the current. And if the calculated average intensity exceeds a preset reference size, it can be determined that the arc generation condition is met. Here, the high frequency band may be a higher frequency band than the low frequency band.

[0087] For convenience, the above-mentioned first frequency band will be assumed to be a low frequency band and the second frequency band will be assumed to be a high frequency band in the following description. However, it goes without saying that the present invention is not limited thereto.

[0088] The first frequency band and the second frequency band may be frequency bands that are not typically used for broadcasting or wireless communication. Additionally, they may be frequency bands where interference caused by wireless signals in frequency bands used for broadcasting or wireless communication is minimized. For example, the first frequency band may be a frequency band where interference between frequency bands occurs minimally between the AM radio broadcasting frequency band and the FM radio broadcasting frequency band. In this case, the first frequency band may be a frequency band where interference caused by other frequency bands occurs minimally among the amateur radio (HAM) frequency band or the frequency band where shortwave broadcasting takes place.

[0089] In addition, the second frequency band may be a frequency band in which interference between frequency bands occurs minimally among the frequency bands of the VHF (Very High Frequency) broadcasting frequency bands using 54~72 MHz (CH 2~4), 76~88 MHz (CH 5~6), and 174~216 MHz (CH 7~13). In this case, the second frequency band may be a frequency band between the frequency band corresponding to channels 5 to 6 (76~88 MHz) and the frequency band corresponding to channels 7 to 13 (174~216 MHz) among the TV broadcasting frequency bands.

[0090] These first frequency bands and second frequency bands can be determined through a plurality of frequency spectrum experiments performed to detect the optimized first frequency bands and second frequency bands in a region or location where an arc detection device according to an embodiment of the present invention is deployed. Examples of the optimal first frequency band (low frequency band) and second frequency band (high frequency band) determined through such frequency spectrum experiment results will be examined in more detail with reference to Fig. 5 below.

[0091] And the control unit (490) can increase the estimated number of times an arc is estimated to have occurred, i.e., the arc count, when it is determined that all of the preset conditions for arc occurrence are satisfied according to the magnitude of the peak current detected through the current detection unit (430) and the HF noise signals of the first frequency band (low frequency band) and the HF noise signals of the second frequency band (high frequency band) detected by the HFCT (400). And during a preset time, it can check whether the number of times the arc is estimated to have occurred, i.e., the arc count, has reached a preset number. And when the arc count reaches a preset reference count, the control unit (490) determines that an arc has occurred and can output a trip control signal to the cut-off unit (450) to drive the cut-off unit (450) so that the load is cut off from the power source.

[0092] Meanwhile, the memory (470) can store a program for the operation of the control unit (490) and can store data that is input or output for the performance of the function of the arc detection device. For example, the memory (470) can store information on zero crossing points detected according to voltage changes detected in the circuit, and can store information on current signals sampled from the current detection unit (430), high-frequency band HF noise signals sampled from the HFCT (400), and low-frequency band HF noise signals.

[0093] Additionally, the memory (470) can store information on reference times for determining a reference count according to the magnitude of the peak current. For example, information on reference times according to the magnitude of the peak current detected according to the voltage flowing in the circuit may be as shown in Table 1 (when the circuit voltage is 230V) and Table 2 (when the circuit voltage is 120V) below.

[0094] Peak current magnitude (A) 2.55 10 16 32 63 Reference time (sec) 10.5 0.25 0.15 0.12 0.12

[0095] Peak current magnitude (A) 5 10 16 3 2 6 3 Reference time (sec) 10.4 0.28 0.14 0.14

[0096] As shown in Tables 1 and 2 above, the reference time can be shortened depending on the magnitude of the peak current. And as the reference time becomes shorter, the value of the count corresponding to the reference time, that is, the reference count value, can be determined to be smaller.

[0097] And the memory (470) can store information regarding conditions for checking whether high-frequency band HF noise signals among the HF noise signals detected by the HFCT (400) satisfy a preset arc generation condition, and conditions for checking whether low-frequency band HF noise signals satisfy a preset arc generation condition. For example, the information of conditions stored in the memory (470) may include information for counting the number of HF noise signal samples having a strength greater than a preset magnitude or more than a preset number of times, and may include information on the preset number of times and the preset signal strength. It may also include information on a reference value for determining whether the arc generation condition is satisfied based on the signal average of the detected HF noise signals. It may also include information on a reference current for determining whether the arc generation condition is satisfied based on the peak current calculated during the half-cycle of the current.

[0098] Additionally, the communication unit (460) may establish a wired or wireless communication connection with a pre-configured external server or a pre-configured terminal. The communication unit (460) may provide measured information to the external server or the pre-configured external terminal through the wired or wireless communication connection. Here, the external server may be a management server that manages the arc detection device according to an embodiment of the present invention, and the external terminal may be a pre-configured user's terminal. In this case, the user's terminal may be a mobile terminal, such as a smartphone, tablet PC, or laptop. 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.

[0099] Meanwhile, the arc detection device may further include an output unit (480) for indicating the operating state of the arc detection device. The output unit (480) may include at least one of a light output unit and an acoustic signal output unit. The light output unit may include at least one LED capable of emitting light of different colors. Additionally, the acoustic output unit may include at least one of a speaker or a buzzer capable of outputting an acoustic signal. In the case of the light output unit, the operating state of the arc detection device may be indicated using light emitted from an LED, etc. And in the case of the acoustic output unit, the operating state of the arc detection device may be indicated using an acoustic signal output from a speaker, etc.

[0100] Additionally, the arc detection device may be configured to include a Zero-phase Current Transformer (ZCT) (440) for detecting leakage current in the circuit. The ZCT can determine whether there is leakage current by comparing the magnitude of the current flowing from the power source to the load through the live wire (L wire) and the magnitude of the current flowing from the load to the power source through the neutral wire (N wire), based on the difference.

[0101] Additionally, the ZCT (440) may be equipped with a Low Pass Filter (LPF) for filtering current noise. In this case, the arc detection device can detect whether leakage current has occurred based on the detection result of the ZCT (440). And if leakage current has occurred, the device can control the cutoff unit (450) to perform a cutoff operation by outputting a trip control signal.

[0102] Here, the aforementioned leakage current may be generated by insulation breakdown at ground. In this case, since insulation breakdown implies the occurrence of an arc, the leakage current may correspond to the occurrence of an arc at ground, i.e., a ground arc. Therefore, the detection of the leakage current is to detect the occurrence of the ground arc, and accordingly, the arc detection device may determine whether a ground arc has occurred and, based on the determination result, disconnect the electrical connection between the power source and the load.

[0103] Meanwhile, the above ZCT (440) is an example of a leakage current detection unit for detecting leakage current, and it goes without saying that the present invention is not limited to having the ZCT (440) as a configuration for detecting leakage current. That is, in the arc detection device according to the embodiment of the present invention, it goes without saying that any other leakage current detection unit capable of detecting leakage current can replace the above ZCT (440).

[0104] Meanwhile, in the above description, it was explained by assuming that the HF noise signal checking whether a sample having a size greater than a preset size has been detected more than a preset number of times is a low-frequency band HF noise signal, and the HF noise signal comparing the average value of the signal strength with a preset reference value is explained by assuming that it is a high-frequency band HF noise signal, but it goes without saying that the present invention is not limited thereto.

[0105] That is, contrary to the above explanation, the HF noise signal that checks whether a sample having a size greater than a preset size has been detected more than a preset number of times is a high-frequency band HF noise signal, and the HF noise signal that compares the average value of the signal strength with a preset reference value may be a low-frequency band HF noise signal.

[0106] Meanwhile, the arc detection device according to an embodiment of the present invention may use HF noise signals detected in different frequency bands to detect arc noise in the form of white noise that occurs when an arc occurs, as described above. However, HF noise in a specific frequency band like this may be affected by, that is, interference, by wireless signals using the same frequency band, and HF noise generated by the energy detected by the interference may be incorrectly detected as arc noise that occurs when an arc occurs.

[0107] To prevent such interference, an arc detection device according to an embodiment of the present invention detects a plurality of frequency bands in which the influence of commonly used wireless signals occurs to a minimum, and the detected frequency bands can be used as frequency bands for detecting the arc noise.

[0108] For example, an arc detection device according to an embodiment of the present invention can detect the frequency band where the least interference occurs among the broadcast frequencies of the VHF band, which is a TV broadcast frequency band. The detected frequency band can be used as a frequency band for a high-frequency band HF noise signal to detect arc noise according to an embodiment of the present invention. In addition, an arc detection device according to an embodiment of the present invention can detect the frequency band where interference occurs minimally among the radio broadcast frequency bands, and the detected frequency band can be used as a frequency band for a low-frequency band HF noise signal to detect arc noise according to an embodiment of the present invention.

[0109] To this end, a plurality of experiments may be performed to detect the frequency spectrum for each of the above broadcast frequencies and radio broadcast frequencies and to determine the optimal frequency band through the detected frequency spectra, and the frequency bands obtained from the results of the plurality of experiments may be used as the frequency band of the high-frequency band HF noise signal and the frequency band of the low-frequency band HF noise signal.

[0110] Figure 5 illustrates examples of frequency spectra for other commonly used wireless signal frequencies, such as TV broadcast frequencies and radio broadcast frequencies, and examples of frequency bands with minimal interference effects determined based on the frequency spectra.

[0111] In this case, since the TV broadcast frequency band has a higher frequency band than the radio broadcast frequency band, the minimum interference frequency band determined in the TV broadcast frequency band can be determined as the frequency band of the high-frequency band HF noise signal according to the embodiment of the present invention. In addition, the minimum interference frequency band determined in the radio broadcast frequency band can be determined as the frequency band of the low-frequency band HF noise signal according to the embodiment of the present invention.

[0112] First, FIG. 5(a) shows an example of analyzing the frequency spectrum of radio signals in the VHF band among TV broadcast frequency bands. In this case, the radio signals in the VHF band may include a first radio frequency band (510) in the 54 MHz to 72 MHz (CH 2~4) band, a second radio frequency band (520) in the 76 MHz to 88 MHz (CH 5~6) band, and a third radio frequency band (530) in the 174 MHz to 216 MHz (CH 7~13) band.

[0113] Meanwhile, as shown in FIG. 5(a), the energy of each radio frequency band can decrease as it moves further away from the center frequency of each radio frequency band. Also, the lower the energy of the overlapping frequency bands, the less the effect of interference can occur. Therefore, as shown in FIG. 5(a), when the frequency spectrum distribution of radio signals in the VHF band is formed, minimum interference frequency bands (501, 502) in which the effect of interference occurs minimally between the first radio frequency band (510) and the second radio frequency band (520), and between the second radio frequency band (520) and the third radio frequency band (530), can be determined.

[0114] And among the above minimum interference frequency bands (501, 502), the second minimum interference frequency (502), which is the minimum interference frequency with lower wireless signal energy (e.g., a frequency band with a center frequency of 150 MHz), may be determined as the frequency band of the high-frequency band HF noise signal used for detecting arc noise in the arc detection device according to an embodiment of the present invention. For convenience of explanation, in the following description, it will be explained by assuming that the second minimum interference frequency (502), which is 150 MHz, is set as the frequency band of the high-frequency band HF noise signal and that the occurrence of an arc is detected.

[0115] Meanwhile, Figure 5(b) shows an example of analyzing the frequency spectrum of wireless signals in the AM radio broadcast frequency band and the FM radio broadcast frequency band.

[0116] Typically, AM radio broadcasting takes place in the frequency band of 0.5 MHz to 1.6 MHz. Also, FM radio broadcasting takes place in the frequency band of 88 MHz to 108 MHz. Accordingly, as shown in FIG. 5 (b), by examining the frequency spectrum (560) for AM radio broadcasting frequencies and the frequency spectrum (570) for FM radio broadcasting frequencies, a minimum interference frequency (550) can be determined between the AM radio center frequency and the FM radio center frequency, where the influence on the AM radio signal and the influence on the FM radio signal are minimized.

[0117] Here, the minimum interference frequency band may be determined to be 3 MHz to 30 MHz, which is the HF band where amateur radio communication, i.e., shortwave broadcasting, occurs sporadically. Alternatively, considering avoidance and interference phenomena between the AM radio broadcast frequency band and the shortwave broadcast frequency band, a frequency band between 1.5 MHz and 2.5 MHz or between 1 MHz and 2 MHz may be determined as the frequency band of the low-frequency band HF noise signal used for detecting arc noise in the arc detection device according to an embodiment of the present invention. For convenience of explanation, in the following description, it will be explained assuming that the frequency band between 1 MHz and 2 MHz is set as the frequency band of the low-frequency band HF noise signal and that the occurrence of an arc is detected.

[0118] Meanwhile, at least one of the high-frequency band detection unit (410) and the low-frequency band detection unit (420) described above may detect only signals that match a specific frequency through a narrow band matching filter (NBMF) formed to detect only signals that match a specific frequency that is set in advance. In this case, if the narrow band matching filter is provided in the high-frequency band detection unit (410), the high-frequency band detection unit (410) may detect only HF noise signals that match a specific frequency band that is set in advance as HF noise signals of the high-frequency band. Alternatively, if the narrow band matching filter is provided in the low-frequency band detection unit (420), the low-frequency band detection unit (420) may detect only HF noise signals that match a specific frequency band that is set in advance as HF noise signals of the low-frequency band.

[0119] FIGS. 6a and FIG. 6b are block diagrams illustrating the structure of an arc detection device according to an embodiment of the present invention, which detects arc noise based on signals in the high-frequency HF noise and low-frequency HF noise bands determined in FIG. 5.

[0120] First, FIG. 6a illustrates in more detail the configuration of a high-frequency band detector (410) that detects HF noise signals of a specific high-frequency band (150 MHz band) through the narrow-band matching filter and compares the average signal strength of the detected high-frequency band HF noise signals, and the configuration of a low-frequency band detector (420) that checks whether signals having a magnitude greater than a preset value have been detected more than a preset number of times from HF noise signals of a preset low-frequency band (1 MHz ~ 2 MHz).

[0121] Referring to FIG. 6a, the high-frequency band detection unit (410) may include a 150 MHz narrowband matching filter (611) that detects only signals having a frequency that matches the 150 MHz frequency set as the frequency band of the currently set high-frequency band HF noise signal, and a logarithmic amplifier (612) that amplifies the HF noise signals detected from the 150 MHz narrowband matching filter (611).

[0122] In this case, the logarithmic amplifier (612) is an amplifier in which the output voltage is proportional to the logarithm of the input voltage, and can amplify the signal strength of 150 MHz HF noise signals to a size recognizable by the control unit (490) and output it to the control unit (490). Accordingly, the high-frequency band detector (410) can provide the signal strength of the high-frequency HF noise to the control unit (490) in the form shown in the signal strength graph (610) which indicates the change in HF noise signal strength over time. Then, the control unit (490) can detect the signal strength of the amplified 150 MHz HF noise signals and calculate the average signal strength of the detected 150 MHz HF noise signals.

[0123] Meanwhile, the low-frequency band detection unit (420) may be equipped with a band-pass filter (621) that detects signals having a frequency of 1 MHz to 2 MHz, which is set as the frequency band of the currently set low-frequency band HF noise signal. It may also be equipped with an amplification unit (622) that amplifies the low-frequency band HF noise signals detected through the band-pass filter (621) according to a preset amplification ratio. Furthermore, it may be configured to include a comparator (623) that compares the magnitude of the amplified low-frequency band HF noise signal with a preset reference voltage.

[0124] Accordingly, the low-frequency band detection unit (420) can amplify the strength of the detected signals whenever HF signals in the 1 MHz to 2 MHz band are detected among the HF noise signals detected by the HFCT (400), and output the result of comparing the amplified signal strength with the magnitude of a preset reference voltage. Therefore, the output of the low-frequency band detection unit (420) may take the form of a pulse signal (620) consisting of a signal having a preset value (e.g., a signal having a value of '1') and a signal not having a preset value (e.g., a signal having a value of '0') according to the comparison result of the comparator (623). And the control unit (490) can detect the number of times signals having a preset magnitude or greater have occurred among the detected preset low-frequency band HF noise signals by counting the number of signals having the preset value in the pulse signal (610).

[0125] Meanwhile, according to the above description, the arc detection device according to an embodiment of the present invention can detect whether a sample having an intensity greater than or equal to the preset size has been detected more than a preset number of times from at least one of the high-frequency band HF noise signal samples and the low-frequency band HF noise signal samples, and whether the average value of the signal samples exceeds a preset reference value.

[0126] Therefore, it is also possible to check whether high-frequency band HF noise signals, rather than low-frequency band HF noise signals, have been detected more than a preset number of times. FIG. 6b illustrates in more detail the configuration of the high-frequency band detection unit (410) and the low-frequency band detection unit (420) of the arc detection device according to an embodiment of the present invention in such a case.

[0127] Referring to FIG. 6b, contrary to FIG. 6a, the high-frequency band detection unit (410) may include a narrow-band matching filter (611) that detects signals having a frequency of 150 MHz band, which is set as the frequency band of the currently set high-frequency band HF noise signal, and an amplification unit (652) that amplifies the HF noise signals detected through the narrow-band matching filter (611) according to a preset amplification ratio. It may also be configured to include a comparator (653) that compares the magnitude of the amplified low-frequency band HF noise signal with a preset reference voltage.

[0128] Accordingly, the high-frequency band detection unit (410) can amplify the HF signals of the 150 MHz band whenever they are detected among the HF noise signals detected by the HFCT (400), and output the result of comparing the magnitude of the amplified signal with the magnitude of a preset reference voltage. Therefore, the output of the high-frequency band detection unit (410) may take the form of a pulse signal (650) consisting of a signal having a preset value and a signal not having a preset value according to the comparison result of the comparator (653). And the control unit (490) can detect the number of times signals having a preset magnitude or greater have occurred among the detected preset high-frequency band HF noise signals by counting the number of signals having the preset value in the pulse signal (650).

[0129] Meanwhile, the low-frequency band detection unit (420) may be equipped with a band-pass filter (621) that detects signals having a frequency of 1 MHz to 2 MHz band, which is set as the frequency band of the currently set high-frequency band HF noise signal, and a log-amplifier (662) that amplifies the HF noise signals detected from the band-pass filter (621).

[0130] In this case, the log amplification unit (612) can amplify the signal strengths of HF noise signals having a frequency of 1 MHz to 2 MHz to a size recognizable by the control unit (490) and output them to the control unit (490). Accordingly, the low frequency band detection unit (420) can provide the detection result of the low frequency HF noise to the control unit (490) in the form of a signal strength graph (660) showing the change in HF noise signal strength over time. Then, the control unit (490) can detect the signal strengths of the amplified 1 MHz to 2 MHz HF noise signals and calculate the average signal strength value of the detected low frequency HF noise signals.

[0131] Meanwhile, since the above-mentioned narrowband matching filter detects only signals that match a specific frequency band, it may be more advantageous to apply it to an HF noise signal that compares the average value of the signal strength with a preset reference value. Therefore, if the condition for arc generation is determined by comparing the average value of the signal strength with a preset reference value for a high-frequency HF noise signal, the above-mentioned narrowband matching filter may be provided in the high-frequency band detection unit (410). Conversely, if the condition for arc generation is determined by comparing the average value of the signal strength with a preset reference value for a low-frequency HF noise signal, the above-mentioned narrowband matching filter may be provided in the low-frequency band detection unit (420).

[0132] For convenience of explanation, the following description will be explained by using the example where the narrowband matching filter is provided in the high-frequency band detection unit (410). However, it goes without saying that the present invention is not limited thereto.

[0133] Meanwhile, FIG. 7 is a flowchart illustrating the operation process of determining whether an arc has occurred based on the detection results of high-frequency HF noise signals and low-frequency HF noise signals in an arc detection device according to an embodiment of the present invention.

[0134] The control unit (490) of the arc detection device according to an embodiment of the present invention can detect the point in time when the polarity of the voltage changes according to the voltage change of the circuit, that is, the point in time when the voltage reaches 0V, as the zero crossing point (ZCP). And when the zero crossing point is detected, current sampling and sampling of HF noise signals can be started until the next zero crossing point is detected.

[0135] In this case, since the zero crossing point occurs periodically during every half-cycle of the alternating current, the current signal and HF noise signal sampled from the zero crossing point to the next zero crossing point may be the current signals and HF noise signals sampled during the half-cycle of the alternating current flowing in the circuit. That is, based on the zero crossing point, sampling of the current signal and the high-frequency noise signal according to a preset sampling interval may be performed during every half-cycle of the current signal.

[0136] To this end, the control unit (490) of the arc detection device according to an embodiment of the present invention may receive a zero-crossing point detected according to a voltage change of the circuit as an interrupt signal. When the interrupt signal is received, sampling of the current signal and the HF noise signal may begin. Sampling may continue until the next interrupt signal is received, that is, until the next zero-crossing point is detected, and when the next interrupt signal is received, sampling may begin again.

[0137] Therefore, whenever a half-cycle of the current signal elapses, the current signals and HF noise signals sampled during each half-cycle can be collected. FIG. 7 may be an operation process that proceeds when the current signal samples and HF noise signal samples collected during the half-cycle are collected in this manner.

[0138] Referring to FIG. 7, the control unit (490) of the arc detection device according to an embodiment of the present invention can increase a preset arc check time count by a preset count value when current signal samples and HF noise signal samples are collected during a half-cycle (S700).

[0139] Here, the arc check time count is intended to check whether a preset initialization time, i.e., a reference time, has elapsed. If no arc is detected while the reference time has elapsed, the estimated number of arc occurrences checked prior to the reference time can be reset. In other words, the arc check time count serves as a valid time during which the estimation of whether an arc has occurred is valid when an arc is estimated; the estimation result of whether an arc has occurred may be valid only for the time corresponding to the arc check time count, i.e., the reference time. Furthermore, the estimation result of whether an arc has occurred may be reset once the reference time has elapsed.

[0140] In step S700 above, when the arc check time count is increased, the control unit (490) can calculate the peak current during the half-cycle (S702). Here, the peak current may be the result of calculating the effective value (e.g., RMS) of the current values ​​of current signals whose magnitude is greater than a certain magnitude among the samples of current signals collected during the half-cycle.

[0141] In step S702 above, when a peak current is calculated, the control unit (490) can determine a reference count based on the magnitude of the calculated peak current (S704).

[0142] In the above S704 step, the larger the magnitude of the calculated peak current, the higher the probability of a strong arc occurring, and the greater the arc intensity, the higher the risk of safety accidents. Therefore, the reference count may be set small so that the arc can be identified more quickly as the magnitude of the peak current increases.

[0143] On the other hand, the smaller the magnitude of the aforementioned peak current, the higher the probability that the arc size will not be large, and if the arc intensity is small, the risk of safety accidents caused by the occurrence of the arc may be low. Conversely, if the circuit between the power source and the load is interrupted, the power supply to the load is cut off, which may result in damage as the load cannot be driven. Therefore, the reference count mentioned above can be set larger so that the arc can be identified more accurately as the magnitude of the peak current decreases.

[0144] Meanwhile, when the reference count is determined in step S704, the control unit (490) can first check whether the peak current calculated in step S702 has exceeded the preset reference current (S706).

[0145] If, as a result of the check in step S706 above, the peak current does not exceed the preset reference current, the control unit (490) can estimate that no arc occurred during the half-cycle. Then, it can check whether the arc check time count accumulated so far has reached the preset reference time count (S722).

[0146] Here, if the frequency of the alternating current is 60Hz, it may be desirable to set the reference time count to 60. In this case, if the reference time count is set to 60, the time corresponding to 60 half-cycles (between ZCPs) may be the time when the reference time count expires, and in this case, the reference time count may correspond to 0.5 seconds according to the frequency of the alternating current of 60Hz.

[0147] In this case, if the frequency of the alternating current is higher, the time corresponding to the reference time count may be shorter even if the reference time count is the same. On the other hand, if the frequency of the alternating current is lower, the time corresponding to the reference time count may be longer even if the reference time count is the same.

[0148] Meanwhile, if the calculated peak current exceeds a preset reference current as a result of the check in step S706, the control unit (490) may determine that the first condition for estimating whether an arc has occurred is satisfied. And if the first condition is satisfied, it may detect whether other conditions for estimating whether an arc has occurred are satisfied.

[0149] The control unit (490) can first calculate the average signal strength of the high-frequency band HF noise signal samples collected during the half-cycle (S708). Then, it can check whether the calculated average signal strength of the high-frequency band HF noise signal samples exceeds a preset reference value (S710). Here, the reference value may be a reference value for estimating whether arc noise occurs based on the average value of the high-frequency band HF noise signal samples.

[0150] If, as a result of the check in step S710 above, the average signal strength of the high-frequency band HF noise signal samples collected during the half-cycle does not exceed a preset reference value, the control unit (490) can estimate that no arc occurred during the half-cycle. Accordingly, the process can proceed to step S722 to check whether the arc check time count has reached a preset reference time count.

[0151] On the other hand, if, as a result of the check in step S710 above, the average signal strength of the high-frequency HF noise signal samples collected during the half-cycle exceeds a preset reference value, the control unit (490) may determine that the second condition for estimating whether an arc has occurred is satisfied. And if the first and second conditions are satisfied, the satisfaction of the third condition for estimating whether an arc has occurred can be detected.

[0152] Then, the control unit (490) can count the number of signals having a preset value from the pulse signals, which are the detection results of the low-frequency band HF noise signals provided by the low-frequency band detection unit (420) (S712). And the control unit (490) can check whether the number of times low-frequency band HF noise signals having a signal strength greater than a preset size are detected during the half-cycle exceeds a preset reference number through the number of the counted signals (S714).

[0153] If, as a result of the comparison in step S714, the number of pulse signals having the preset value does not exceed the reference number, the control unit (490) can presume that no arc occurred during the half-cycle. Accordingly, the process can proceed to step S722 to check whether the arc check time count has reached the preset reference time count.

[0154] On the other hand, if, as a result of the check in step S714 above, the number of times low-frequency band HF noise signals having a signal strength greater than the preset size are detected during the half-cycle exceeds the reference number, the control unit (490) may determine that the third condition for estimating whether an arc has occurred is satisfied. And if all three conditions for estimating whether an arc has occurred are satisfied, it may be estimated that an arc has occurred during the half-cycle.

[0155] Then, the control unit (490) can increase the arc count (e.g., increase the arc count value by 1) (S716). Then, the control unit (490) can check whether the arc count accumulated so far has reached a preset reference count, that is, whether it is greater than or equal to the preset reference count (S718). Here, the reference count may be a reference count determined according to the peak current in step S704.

[0156] If, as a result of the check in step S718 above, the arc count accumulated to date is less than the reference count value, the control unit (490) can proceed to step S722 above to check whether the arc check time count has reached the preset reference time count.

[0157] However, if, as a result of the check in step S718 above, the arc count accumulated to date is greater than or equal to the reference count value, the control unit (490) may determine that an arc has occurred. Accordingly, a trip control signal may be transmitted to the cutoff unit (450) to cut off the load from the power source (S720). Then, depending on the operation of the cutoff unit (450), the circuit between the power source and the load is opened, and the power supply to the load may be cut off.

[0158] Meanwhile, if the peak current in step S706 is less than or equal to the reference current, or if the average signal strength of the high-frequency band HF noise signal samples in step S710 is less than or equal to the reference value, or if the number of times low-frequency band HF noise signals having a signal strength greater than or equal to the preset size are detected during the half-cycle in step S714 does not exceed the reference number, or if the arc count counted so far is less than the reference count, the control unit (490) may proceed to step S722, which checks whether the arc check time count has reached the preset reference time count.

[0159] And if, as a result of the check in step S722 above, the arc check time count accumulated to date has not reached the preset reference time count, the control unit (490) can proceed to step S700 again to increase the arc check time count. Then, proceed to the following steps to check whether the conditions for estimating whether an arc has occurred are satisfied, and determine whether an arc has occurred based on the check result.

[0160] On the other hand, if the result of the check in step S722 above indicates that the arc check time count accumulated to date has reached a preset reference time count, the control unit (490) can reset the arc check time count accumulated to date (S724).

[0161] For example, if the reference time count is set to '60' as described above, when the arc check time count that has been increased up to this point reaches '60', the arc check time count can be initialized to 0 through steps S722 and S724.

[0162] And when the arc check time count is reset, the control unit (490) can reset the arc count accumulated up to that point. Then, it can proceed to step S700 again to increase the reset arc check time count by 1 and perform the processes below step S700 again. Accordingly, the control unit (490) can determine whether an arc has occurred at intervals according to the arc check time count and cut off the load from the power supply depending on whether an arc has occurred.

[0163] Meanwhile, in contrast, the control unit (490) can selectively reset the arc counts that were checked prior to the reference time count among the arc counts checked so far when the arc check time count is initialized in step S724 (S726). Accordingly, at least some of the arc counts that were counted prior to the reference time count (e.g., 60) among the arc counts accumulated so far can be initialized. Therefore, the value of the arc count accumulated so far can be reduced.

[0164] For example, when the arc check time count reaches 50, the arc count is counted (arc counting '1'). When the arc check time count reaches 60, the arc check time count can be reset to 0. However, the arc count can remain in the state where it is counted as 1.

[0165] And when the arc check time count becomes 20 again, if the arc count is counted, the arc count can be increased to 2. Also, when the arc check time count becomes 59, if the arc count is counted, the arc count can be increased to 3. In this state, if the arc check time count becomes 60 again, the arc check time count can be reset to 0.

[0166] However, in this case, among the arc counts counted up to now, the first arc count counted may be an arc count counted 60 arc check time counts (reference time counts) prior to the point when the arc check time count was initialized to 0. In the example above, the first arc count may be an arc count counted before the time corresponding to 70 arc check time counts.

[0167] Accordingly, the control unit (490) can initialize the arc count that occurred prior to the reference time count among the arc counts counted up to now in step S724. That is, as the first arc count is initialized, the arc count can be reduced from 3 to 2. Then, the control unit (490) can proceed to step S700 again with the arc count counted prior to the reference time count initialized and increase the arc check time count. That is, the control unit (490) can proceed to step S700 again with some arc counts initialized and the remaining arc counts maintained, increase the initialized arc check time count by 1, and perform the processes below step S700 again.

[0168] To this end, the control unit (490) can store information of an arc check time count corresponding to the counted arc count in the memory (470) whenever the arc count is counted.

[0169] Meanwhile, in the above-described FIGS. 6a and 6b, the high-frequency band detection unit (410) and the low-frequency band detection unit (420) are each equipped with an amplification unit to simultaneously detect both the high-frequency band HF noise signal and the low-frequency band HF noise signal, but it is obvious that the control unit (490) can detect the high-frequency band HF noise signal and the low-frequency band HF noise signal by dividing the time.

[0170] In this way, when the time at which high-frequency HF noise signals and low-frequency HF noise signals are detected is distinguished, one amplifier can be configured to amplify both the detected high-frequency HF noise signals and low-frequency HF noise signals.

[0171] FIG. 8 is a block diagram illustrating the configuration of an arc detection device according to another embodiment of the present invention.

[0172] Referring to FIG. 8, the control unit (800) can divide the time corresponding to the period determining whether an arc occurs, for example, the time corresponding to a half-cycle of the current. And a part of the divided time can detect a high-frequency HF noise signal, and the remaining part can detect a high-frequency HF noise signal. Accordingly, during the time when the high-frequency HF noise signal is detected, the high-frequency narrowband matching filter (e.g., 150 MHz NBMF of FIG. 6a or 6b) (810) can be activated, and during the time when the low-frequency HF noise signal is detected, the low-frequency bandpass filter (e.g., 1 MHz to 2 MHz BPF of FIG. 6a or 6b) (820) can be activated.

[0173] And when high-frequency HF noise signals and low-frequency HF noise signals are detected during the above half-cycle, it is possible to determine whether an arc has occurred according to the operation process of FIG. 7. In this case, as the time during which the low-frequency HF noise signal is detected is limited, the number of low-frequency HF noise signals may be reduced; taking this into consideration, the value of the reference count, which is compared with the number of signals counted from the pulse train in step S714 of FIG. 7, may have a smaller value.

[0174] In the case of having a configuration as shown in FIG. 8, the high-frequency narrowband matching filter (810) can be activated for a certain period of time under the control of the control unit (800). Then, HF noise signals of a preset high-frequency band are detected through the activated high-frequency narrowband matching filter (810) and can be amplified to a size recognizable by the control unit (800) by the amplification unit (830). Then, the control unit (800) receives the high-frequency band HF noise signals with amplified signal strength and can calculate the average signal strength of the received high-frequency band HF noise signals.

[0175] Meanwhile, when the above preset time expires, the high-frequency narrowband matching filter (810) may be deactivated under the control of the control unit (800). Then, the low-frequency bandpass filter (820) may be activated for another set period of time under the control of the control unit (800). Then, HF noise signals of the preset low-frequency band are detected through the activated low-frequency bandpass filter (820) and can be amplified by the amplification unit (830) to a size recognizable by the control unit (800).

[0176] Then, the control unit (800) receives low-frequency band HF noise signals with amplified signal strength and can detect the number of signals among the received low-frequency band HF noise signals whose signal strength is greater than or equal to a preset strength. Then, the control unit (800) can determine whether an arc occurs according to FIG. 7 based on the average signal strength of the high-frequency band HF noise signals and the number of low-frequency HF noise signals that are greater than or equal to the preset strength.

[0177] In this case, the ratio of the time during which the high-frequency band HF noise signals are detected to the time during which the low-frequency band HF noise signals are detected can be determined by the control unit (800). For example, the control unit (800) can decrease the ratio of the time during which the HF noise signal of the frequency band with more interference is detected and increase the ratio of the time during which the HF noise signal of the frequency band with less interference is detected.

[0178] That is, in areas where interference with low-frequency HF noise signals may be severe (e.g., coastlines - where shortwave communication for marine communication exists), the ratio of the time during which the low-frequency HF noise signal is detected can be reduced, and the ratio of the time during which the high-frequency HF noise signal is detected can be increased. In this case, the ratio of the times during which HF noise signals of each frequency band are detected for each region can be predetermined as an optimized value through a number of experimental results related to the present invention.

[0179] Meanwhile, depending on the determined time ratio, the control unit (800) may reduce or increase the reference count of step S714 of FIG. 7. That is, as described above, if the HF noise signal detection time of the frequency band in which the number of signals having a signal strength greater than a certain magnitude is counted increases, the control unit (800) may increase the reference count for comparing the number of counted signals according to the increased detection time.

[0180] On the other hand, if the detection time of the HF noise signal in the frequency band in which the number of signals having a signal strength greater than or equal to the above-mentioned magnitude is counted is reduced, the control unit (800) can reduce the reference number for comparing the number of counted signals according to the reduced detection time.

[0181] The present invention described above can be implemented as computer-readable code on a medium on which a program is recorded. A computer-readable medium includes all types of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable media include HDD (Hard Disk Drive), SSD (Solid State Disk), SSD (Silicon Disk Drive), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., and also include implementation in the form of a carrier wave (e.g., transmission over the Internet).

[0182] Additionally, the computer may include a control unit (490 or 800) of the arc detection device. Accordingly, the above detailed description should not be interpreted restrictively in all respects and should be considered exemplary. The scope of the invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention.

Claims

1. A current detection unit for detecting current flowing in an electrical circuit; A high-frequency signal detection unit that detects an HF (High Frequency) noise signal from the above circuit; A first band detection unit that detects HF noise signals of a preset first frequency band among the detected HF noise signals; A second band detection unit for detecting HF noise signals of a second frequency band different from the first frequency band among the detected HF noise signals; and, An arc detection device characterized by including a control unit that estimates whether an arc has occurred based on the magnitude of a current detected from the circuit during a preset time, the number of times a signal having a strength greater than a preset magnitude among noise signals detected from either the first frequency band or the second frequency band is detected during the preset time, and the average signal strength of noise signals detected from the other of the first frequency band and the second frequency band, determines whether an arc has occurred in the circuit based on whether the number of times an arc has occurred is greater than or equal to a preset reference number, and controls a circuit breaker to cut off the circuit according to the determined arc occurrence.

2. In Paragraph 1, Either of the first frequency band and the second frequency band is a low frequency band with a lower frequency band than the other, and An arc detection device characterized in that the other of the first frequency band and the second frequency band is a high frequency band with a higher frequency band than either one.

3. In Paragraph 2, The above low frequency band is, It is a frequency band between the AM radio frequency band and the FM radio frequency band, and The above high frequency band is, An arc detection device characterized by being a frequency band between the frequency band corresponding to channels 5 to 6 and the frequency band corresponding to channels 7 to 13 among the TV broadcast frequency bands of the VHF (Very High Frequency) band.

4. In Paragraph 3, The above high frequency band is a frequency band with a center frequency of 150 MHz, and An arc detection device characterized in that the above low frequency band is a frequency band between 1 MHz and 2 MHz, or a frequency band where shortwave broadcasting takes place.

5. In Paragraph 1, Either one of the first band detector and the second band detector is HF noise signals having frequencies included within the preset frequency band range are detected through a band-pass filter that detects signals having frequencies included within the preset frequency band range, and The other one of the first band detector and the second band detector is, An arc detection device characterized by detecting HF noise signals matched to a specific frequency band through a narrowband matching filter that detects signals matched to a specific frequency band.

6. In Paragraph 1, Either one of the first band detector and the second band detector is An arc detection device characterized by outputting a pulse signal having a preset value or a pulse signal not having the preset value to the control unit, depending on the result of comparing the signal strength of detected HF noise signals with a preset reference voltage.

7. In paragraph 6, the control unit is, An arc detection device characterized by counting the number of pulse signals having the above-mentioned preset value, and counting the number of times a signal having a strength greater than or equal to a preset magnitude among noise signals detected from either the first frequency band or the second frequency band is detected during the above-mentioned preset time.

8. In paragraph 1, the previously set time is, It is a time corresponding to a half-cycle of the current flowing in the above circuit, and The above control unit is, An arc detection device characterized by detecting a zero crossing point according to the phase alternation of the voltage detected from the voltage change of the above-mentioned circuit, and determining the time corresponding to the half-cycle of the current based on the detected zero crossing point.

9. In paragraph 1, the control unit is, The reference number is determined based on the magnitude of the peak current detected during the half-cycle of the above current, and The above standard number is, An arc detection device characterized by being determined to be smaller as the magnitude of the detected peak current increases.

10. In Paragraph 1, The above-mentioned first band detector is, It is activated for a portion of the above-mentioned preset time, and detects HF noise signals of the first frequency band during the activated time, and The above second band detector is, It is activated for the remaining time excluding a portion of the time set above, and detects HF noise signals of the second frequency band during the activated time, and The above control unit is, An arc detection device characterized by determining the ratio of the time during which the first band detection unit is activated and the time during which the second band detection unit is activated, depending on the region where the arc detection device is placed.

11. A step of calculating the peak current for a certain period of time from a current-carrying circuit; A step of detecting, from the circuit during the above predetermined time, HF (High Frequency) noise signals of a preset first frequency band and HF noise signals of a second frequency band different from the first frequency band; A step of calculating the average signal strength of noise signals detected from either the first frequency band or the second frequency band when, as a result of comparing the peak current and the preset reference current, the arc generation conditions according to the reference current are satisfied; If, as a result of comparing the calculated average signal strength with a preset reference value, the arc generation condition according to the preset reference value is satisfied, a step of counting the number of times a signal having a strength greater than or equal to a preset magnitude among the noise signals detected from the other of the first frequency band and the second frequency band is detected during the preset time period; A step of comparing the above-mentioned count with a preset reference count, and if the arc generation condition according to the preset reference count is satisfied, increasing the arc count and comparing the accumulated arc count with the preset reference count; and, A control method for an arc detection device characterized by including the step of interrupting the electrical connection between the power source and the load by interrupting the circuit when, as a result of comparing the accumulated arc count and the reference count, the arc generation conditions according to the reference count are satisfied.

12. In Paragraph 11, Either of the first frequency band and the second frequency band is a high frequency band with a higher frequency band than the other, and A control method for an arc detection device characterized in that the other of the first frequency band and the second frequency band is a low frequency band with a frequency band lower than that of either one.

13. In Paragraph 11, The step of counting the number of times a signal having a strength greater than or equal to the above-mentioned preset size is detected during the above-mentioned time period is A step of comparing the signal strength of HF noise signals detected from the other of the first frequency band and the second frequency band with a preset reference voltage; A step of generating a pulse signal having a preset value or a pulse signal not having the preset value according to the result of comparing the signal strength of the above HF noise signals with the reference voltage; and, A control method for an arc detection device characterized by including a step of counting the number of pulse signals having the above-mentioned preset value, and counting the number of times a signal having a strength greater than or equal to the above-mentioned preset magnitude among noise signals detected from the other of the first frequency band and the second frequency band is detected during the above-mentioned time.

14. In claim 11, the step of detecting the peak current is, It further includes a step of increasing an arc check time count to check whether a preset initialization time has been reached, The steps of calculating the average signal strength, counting the number of times a signal having a strength greater than or equal to a preset magnitude is detected during a set period of time, comparing the accumulated arc count with a preset reference count, and disconnecting the electrical connection between the power source and the load are: A control method for an arc detection device, characterized by further including a step of initializing the accumulated arc count according to whether the time according to the arc check time count has reached the initialization time when each of the above arc generation conditions is not satisfied.

15. In paragraph 14, the step of initializing the accumulated arc count is, A step of detecting the number of at least one arc count that was counted prior to the initialization time among the accumulated arc counts; and, A control method for an arc detection device characterized by including the step of initializing at least a portion of the accumulated arc counts according to the number of at least one arc count detected above.

16. In Paragraph 11, the above fixed time is, A control method for an arc detection device characterized by being a time corresponding to a half-cycle of the current flowing in the above current, and a time that varies according to the frequency of the current flowing in the above circuit.

17. In Paragraph 11, The step of calculating the above peak current is, The method further includes the step of determining the reference number according to the magnitude of the peak current calculated during the above-mentioned period, The above standard number is, A control method for an arc detection device characterized by determining that the magnitude of the detected peak current is smaller as the magnitude of the peak current is larger.

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