Insulation Deterioration Determination Device and Insulation Deterioration Determination Method

Abstract

To provide a device and method for determining insulation deterioration, which enable accurate determination of insulation deterioration.SOLUTION: An insulation deterioration determination device is provided, comprising: an acquisition unit 2 configured to acquire noise signals on lines (first voltage line L1, neutral line N, and second voltage line L2); and an analysis unit 3 configured to compute a frequency spectrum representing data on a frequency axis using the noise signals to perform an analysis for determining the presence or absence of insulation deterioration between the lines on the basis of the frequency spectrum.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an insulation deterioration determining device and an insulation deterioration determining method. [Background technology]

[0002] A conventional technique for detecting insulation deterioration, typically caused by the tracking phenomenon, is described in, for example, Patent Document 1 listed below.

[0003] Patent document 1 discloses an apparatus configured such that, based on the minute current detected by a detection means, a judgment means determines that a tracking discharge has occurred and outputs an alarm signal when at least two of the calculation results of the charge calculation means, the occurrence frequency value by the occurrence frequency monitoring means, and the calculation results of the level calculation means exceed threshold values. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-279205 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, because noise signals on lines are easily affected by various factors, the conventional technology has room for improvement in the accuracy of determining insulation deterioration occurring between lines.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide an insulation degradation determining device and an insulation degradation determining method that are capable of determining insulation degradation with high accuracy. [Means for solving the problem]

[0007] In order to achieve the above object, the insulation deterioration determination device of the present invention comprises: An acquisition unit for acquiring a noise signal on a line; an analysis unit that calculates a frequency spectrum, which is data on a frequency axis, using the noise signal and performs an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum; Equipped with.

[0008] According to the above configuration, the noise signal on the line is calculated into a frequency spectrum, and whether or not insulation deterioration has occurred is determined based on the frequency spectrum. This makes it easier to distinguish environmental factors that have little direct relationship to insulation deterioration occurring between the lines from the noise signal, and makes it easier to capture the characteristics of the noise components caused by insulation deterioration, making it possible to accurately determine insulation deterioration.

[0009] The insulation deterioration determination method of the present invention further comprises the steps of: An acquisition step of acquiring a noise signal on a line; an analysis step of calculating a frequency spectrum, which is data on a frequency axis, using the noise signal, and performing an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum; has.

[0010] According to the above method, as with the insulation degradation determination device, it becomes easier to distinguish environmental factors that have little direct relationship to insulation degradation that occurs between lines from noise signals, and it becomes easier to capture the characteristics of noise components caused by insulation degradation, making it possible to accurately determine insulation degradation. Effect of the Invention

[0011] According to the insulation deterioration determining device and insulation deterioration determining method of the present invention, insulation deterioration can be determined with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a configuration of an insulation deterioration determination device according to an embodiment of the present invention; [Diagram 2] 4 is a block diagram showing a configuration of an acquisition unit of the insulation deterioration determination device; FIG. [Diagram 3]FIG. 1A is a diagram showing a frequency spectrum when no insulation deterioration occurs, and FIG. 1B is a diagram showing a frequency spectrum when insulation deterioration occurs. [Figure 4] FIG. 11 is a diagram illustrating an example of power consumption in one day. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an insulation deterioration determining device according to the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of an insulation deterioration determination device 1 according to the present embodiment. As shown in Fig. 1, the insulation deterioration determination device 1 includes an acquisition unit 2, an analysis unit 3, a current measurement unit 4, and a setting unit 5. The insulation deterioration determination device 1 is incorporated in, for example, a distribution board D installed in each home.

[0014] In this embodiment, a single-phase three-wire system will be described as a power distribution system for supplying electricity to each home. The single-phase three-wire system has three core wires: a first voltage wire L1, a neutral wire N, and a second voltage wire L2. Through the line formed by the first voltage wire L1, the neutral wire N, and the second voltage wire L2, commercial power with a power supply frequency of, for example, 50 Hz / 60 Hz is supplied to a load P (electronic device, etc.). In this embodiment, the "line" is not limited to the line formed by the first voltage wire L1, the neutral wire N, and the second voltage wire L2, but also includes internal wiring of electronic device, etc. connected as a load.

[0015] The acquisition unit 2 is connected to the first voltage line L1, neutral line N, and second voltage line L2 in the distribution board D. The acquisition unit 2 acquires noise signals on the lines (the first voltage line L1, neutral line N, second voltage line L2, and load wiring). The acquisition unit 2 acquires, for example, a noise signal between the lines of the first voltage line L1 and the neutral line N, and a noise signal between the lines of the second voltage line L2 and the neutral line N, and transmits these acquired noise signals to the analysis unit 3. A detailed configuration of the acquisition unit 2 will be described later with reference to FIG. 2.

[0016] The analysis unit 3 is composed of at least one electronic control unit (MCU: Micro Control Unit). The electronic control unit includes a computer system (e.g., SoC (System on a Chip) or the like) having one or more processors and memories, and an electronic circuit composed of active elements such as transistors and passive elements such as resistors. The analysis unit 3 includes a memory unit 31, a comparison unit 32, and a determination unit 33.

[0017] The analysis unit 3 performs frequency analysis of the noise signal received from the acquisition unit 2 using a Fast Fourier Transform to calculate a frequency spectrum, which is data on the frequency axis. Based on the calculated frequency spectrum, the analysis unit 3 performs an analysis to determine whether or not insulation deterioration has occurred between the lines (first voltage line L1-neutral line N, second voltage line L2-neutral line N).

[0018] The memory unit 31 stores a comparison frequency spectrum that is calculated based on a test signal obtained in a test environment in which no insulation deterioration occurs between the lines (first voltage line L1-neutral line N or second voltage line L2-neutral line N), i.e., a test signal that does not contain noise components caused by insulation deterioration.

[0019] The comparison unit 32 compares, for example, a level of a first frequency spectrum calculated from a noise signal between the first voltage line L1 and the neutral line N and a level of a second frequency spectrum calculated from a noise signal between the second voltage line L2 and the neutral line N with a predetermined threshold. The comparison unit 32 also compares, for example, the level of the first frequency spectrum with the level of the second frequency spectrum. The comparison unit 32 also compares, for example, the level of a comparison frequency spectrum stored in the storage unit 31 with the level of the first frequency spectrum or the second frequency spectrum. The "level" of a frequency spectrum means the intensity of a noise signal.

[0020] The determination unit 33 determines whether or not insulation degradation has occurred between the lines based on the comparison result obtained by the comparison unit 32. The determination unit 33 also determines whether or not insulation degradation is to be determined based on the current value measured by the current measurement unit 4.

[0021] The current measurement unit 4 is a measurement unit for measuring the current flowing on the lines (first voltage line L1, second voltage line L2). The current flowing on the lines refers to the current consumed by a load P (electronic device, etc.).

[0022] The setting unit 5 is configured to be able to select and set, in a stepwise manner, a threshold value to be compared with the level of a frequency spectrum calculated from a noise signal between lines. The setting unit 5 is also configured to be able to select and set, in a stepwise manner, a threshold value to be compared with a current consumption measured by the current measuring unit 4. The setting unit 5 is configured, for example, with a changeover switch capable of switching the threshold value.

[0023] The specific analysis content of the analysis unit 3 is as follows. For example, the analysis unit 3 performs an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum within a predetermined frequency band in the calculated frequency spectrum. The "predetermined frequency band" is a frequency band ranging from 1 MHz to 3 MHz.

[0024] When the level of the frequency spectrum exceeds a predetermined threshold T1 within a predetermined frequency band (for example, 1 MHz to 3 MHz), the analysis unit 3 determines that insulation deterioration has occurred between the lines. The "predetermined threshold T1" is, for example, 46 dBμV. "46 dBμV" is a value equivalent to the standard value of VCCI Class B. In other words, the standard value applied to general household electronic devices connected as the load P is set as the threshold.

[0025] In addition, for example, the analysis unit 3 performs an analysis to determine whether or not insulation degradation has occurred between the lines by utilizing periodic characteristics on the frequency axis due to noise components caused by insulation degradation that appear in the frequency spectrum when insulation degradation occurs.

[0026] When the level of the frequency spectrum is detected multiple times at a predetermined range value at a regular interval on the frequency axis within a predetermined frequency band (1 MHz to 3 MHz), the analysis unit 3 determines that insulation deterioration has occurred between the lines. The feature of "predetermined range value at regular intervals" is one of the periodic features described above. The "regular interval" is, for example, a value in the range of 300 KHz to 500 KHz. The "predetermined range value" is, for example, a value in the range of 40 dBμV to 46 dBμV.

[0027] The analysis unit 3 determines that insulation deterioration has occurred between the lines when the level of the frequency spectrum exceeds a predetermined threshold T1 at regular intervals on the frequency axis within a predetermined frequency band (1 MHz to 3 MHz). The characteristic of "exceeding a predetermined threshold at regular intervals" is one of the periodic characteristics described above. The "regular intervals" is, for example, a value within a range of 300 KHz to 500 KHz. The "predetermined threshold T1" is, for example, 46 dBμV.

[0028] The analysis unit 3 compares a first frequency spectrum calculated from a noise signal between the first voltage line L1 and the neutral line N with a second frequency spectrum calculated from a noise signal between the second voltage line L2 and the neutral line N, and determines that insulation degradation has occurred when a difference value between the first frequency spectrum and the second frequency spectrum, which is the comparison result, exceeds a predetermined threshold value T3. The "predetermined threshold value T3" is, for example, 5 dBμV.

[0029] The analysis unit 3 compares a comparison frequency spectrum (e.g., 35 dBμV or less) calculated based on a test signal acquired in a test environment where no insulation deterioration occurs between the lines with the first frequency spectrum or the second frequency spectrum, and determines that insulation deterioration has occurred when the difference value between the two frequency spectra, which is the comparison result, exceeds a predetermined threshold value T4. The "predetermined threshold value T4" is, for example, 10 dBμV.

[0030] In addition, when the difference value between the two frequency spectra, which is the comparison result, does not exceed a predetermined threshold value T4, the analysis unit 3 determines whether the difference value exceeds a predetermined threshold value T5 (T5 < T4). When it exceeds the threshold value T5, the frequency of occurrence of the frequency spectrum exceeding the threshold value T5 is measured. The analysis unit 3 may determine that insulation degradation has occurred when the frequency of occurrence exceeds a predetermined frequency.

[0031] Also, for example, the analysis unit 3 receives the current consumed by the load P measured by the current measurement unit 4 from the current measurement unit 4, and determines whether to perform an analysis of insulation degradation between the lines according to the current value of the consumed current. When the current consumed by the load P measured by the current measurement unit 4 is equal to or less than a predetermined threshold value, the analysis unit 3 performs an analysis to determine whether insulation degradation has occurred between the lines. In addition, when the current consumed by the load P measured by the current measurement unit 4 is in an upward trend, the analysis unit 3 does not perform an analysis to determine whether insulation degradation has occurred between the lines.

[0032] Further, when the analysis unit 3 determines as a result of the analysis that insulation degradation has occurred between the lines, the analysis unit 3 transmits a cutoff signal for cutting off the breaker (disconnector) B of the distribution board D to the distribution board D, and outputs an alarm signal for notifying that insulation degradation has occurred to the outside.

[0033] Next, with reference to FIG. 2, the configuration and functions of the acquisition unit 2 will be described. As shown in FIG. 2, the acquisition unit 2 includes a coil H, a capacitor C, a resistor R, a low-pass filter circuit 21, an oscillator 22, a frequency coupling unit 23, a band-pass filter circuit 24, an amplifier 25, and an A / D conversion circuit 26.

[0034] One end of the coil H of the acquisition unit 2 is connected to the first voltage line L1 or the second voltage line L2 of the distribution board D. One end of the resistor R is connected to the neutral line N of the distribution board D. When measuring the noise components of the lines (the first voltage line L1, the neutral line N, and the second voltage line L2), if the impedance of the line is low, the noise amount is measured to be small, and conversely, if the impedance is high, the noise amount is measured to be large.

[0035] Therefore, after the noise signal between the voltage lines L1, L2 and the neutral line N is passed through a low-pass filter circuit 21, the noise signal and the oscillation frequency signal of the oscillator 22 are frequency-coupled in a frequency combiner 23 to reduce the noise frequency to an intermediate frequency (the frequency of the "noise signal" - "oscillation frequency signal") that is easy to analyze. Then, the noise signal that has been reduced to the intermediate frequency is input to a band-pass filter circuit 24 to obtain a noise signal in a predetermined frequency band (1 MHz to 3 MHz).

[0036] At this time, since the bandpass filter circuit 24 is configured as a constant impedance circuit terminated with a resistor (50Ω), the impedance of the insulation deterioration determination device 1 seen from the line side is fixed, and the fluctuation amplitude of the noise component contained in the noise signal can be reduced. The noise signal that has passed through the bandpass filter circuit 24 is amplified to a predetermined amplitude by the amplifier 25, converted into a digital signal by the A / D conversion circuit 26, and then input to the analysis unit 3.

[0037] Next, a specific example of the analysis operation performed by the insulation deterioration determining device 1 will be described with reference to FIGS.

[0038] Figure 3(a) shows a comparative frequency spectrum calculated from the noise signal between the lines when there is no insulation degradation, and Figure 3(b) shows a frequency spectrum calculated from the noise signal between the lines when there is insulation degradation.

[0039] (First operation example) The acquisition unit 2 of the insulation deterioration determination device 1 acquires a noise signal between the first voltage line L1 and the neutral line N in the distribution board D, and a noise signal between the second voltage line L2 and the neutral line N.

[0040] The analysis unit 3 of the insulation deterioration determining device 1 performs frequency analysis of the noise signal acquired by the acquisition unit 2 using a fast Fourier transform to calculate a frequency spectrum.

[0041] As shown in Fig. 3(a), the comparison frequency spectrum when no insulation degradation occurs has a stable noise level of about 30±2-3 dBμV in the frequency band of 1 MHz to 3 MHz. In contrast, as shown in Fig. 3(b), the frequency spectrum when insulation degradation occurs has a large fluctuation in noise level in the frequency band of 1 MHz to 3 MHz. Note that "noise level" refers to the intensity of the noise signal, and is shown as the value on the vertical axis in the figure.

[0042] Therefore, the analysis unit 3 judges whether or not the noise level of the frequency spectrum exceeds 46 dBμV, which is the threshold value T1, in the frequency band of 1 MHz to 3 MHz. When the noise level of the frequency spectrum exceeds 46 dBμV in the frequency band of 1 MHz to 3 MHz, the analysis unit 3 judges that insulation deterioration has occurred between the lines. When the analysis unit 3 judges that insulation deterioration has occurred, it outputs a tripping signal and a notification signal. Breaker B is tripped based on the tripping signal, and, for example, an alarm sound is output based on the notification signal.

[0043] (Second operation example) As in the first operation example, the acquisition unit 2 acquires a noise signal between the lines, and the analysis unit 3 performs a fast Fourier transform on the acquired noise signal to calculate a frequency spectrum.

[0044] As shown in FIG. 3(b), in the frequency spectrum when insulation deterioration occurs, the noise level fluctuates significantly at regular intervals on the frequency axis (at regular intervals within the range of 300 KHz to 500 KHz) in the frequency band of 1 MHz to 3 MHz.

[0045] Specifically, in Fig. 3(b), the noise level of the frequency spectrum fluctuates significantly around 1.4 MHz, 1.8 MHz, and 2.2 MHz, as indicated by the dashed lines. The maximum fluctuation reaches 40 dBμV to 46 dBμV. These 1.4 MHz, 1.8 MHz, and 2.2 MHz values ​​are spaced 400 KHz apart on the frequency axis, and this interval falls within the range of 300 KHz to 500 KHz.

[0046] Therefore, the analysis unit 3 judges whether the noise level of the frequency spectrum exceeds the threshold value T0 of 40 dBμV multiple times at a fixed interval within the range of 300 KHz to 500 KHz in the frequency band of 1 MHz to 3 MHz, and if it exceeds the threshold value multiple times at the fixed interval, it judges that insulation deterioration has occurred between the lines. If the analysis unit 3 judges that insulation deterioration has occurred, it outputs a blocking signal and a notification signal.

[0047] (Third operation example) When the electronic device connected as the load P is in operation, noise with a frequency specific to the electronic device is generated, although the standard value of VCCI Class B is met. Therefore, the noise signal acquired between the lines may contain equipment noise generated from the electronic device. Therefore, when determining whether insulation deterioration has occurred between the lines, the analysis unit 3 of the insulation deterioration determination device 1 performs the following analysis in order to suppress the influence of noise generated from the load P (electronic device).

[0048] Fig. 4 is a diagram showing an example of the daily power consumption of a four-person household. As shown in Fig. 4, power consumption tends to be high around breakfast time when people start to get active, and around dinner time when people come home from outside and eat, and power consumption tends to be low during the daytime when many people are out and late at night when people go to bed.

[0049] Therefore, the analysis unit 3 receives the current consumption of the load P measured by the current measurement unit 4 from the current measurement unit 4, and if the power consumption calculated from the current consumption is equal to or less than 0.4 KWh, which is a predetermined threshold value T2, performs an analysis to determine whether or not insulation deterioration has occurred between the lines.

[0050] The method of determining whether insulation deterioration has occurred is similar to that of the first and second operation examples described above.

[0051] (Fourth operation example) Depending on the type of electronic device connected as the load P, for example, when an inductive load or an inverter load is connected, high noise may be generated from these electronic devices. Therefore, when these electronic devices are driven, the noise generated from the electronic devices is likely to affect the determination of whether insulation degradation has occurred between the lines. Therefore, in order to prevent erroneous determination of the occurrence of insulation degradation due to the noise generated from these electronic devices, the analysis unit 3 of the insulation degradation determination device 1 performs the following analysis.

[0052] The analysis unit 3 receives the current consumption of the load P measured by the current measurement unit 4 from the current measurement unit 4, and measures the state of the received current consumption. The analysis unit 3 also calculates a frequency spectrum based on the noise signal acquired by the acquisition unit 2. When the analysis unit 3 determines that the noise level of the frequency spectrum exceeds the threshold T1 (46 dBμV), it determines whether the current consumption of the load P is on an upward trend. When the analysis unit 3 determines that the current consumption of the load P is on an upward trend, it compares the timing at which the noise level of the frequency spectrum exceeded the threshold T1 (46 dBμV) with the timing of the upward trend of the current consumption of the load P. When the two timings match, the analysis unit 3 determines that the increase in the noise level is due to the influence of the load P, and does not perform an analysis to determine whether insulation deterioration has occurred between the lines.

[0053] (Fifth operation example) In order to prevent erroneous determination of the occurrence of insulation degradation, the analysis unit 3 may perform the following analysis.

[0054] When the analysis unit 3 determines that insulation deterioration has occurred between the lines, it measures whether or not the consumption current of the load P measured by the current measurement unit 4 has increased at the time of the determination. When the consumption current of the load P is increasing at the time of the determination, the analysis unit 3 temporarily stores the determination as a "provisional determination" associated with the increase in consumption current. After that, when it is determined that insulation deterioration has occurred between the lines in the same manner with the increase in the consumption current of the load P, it determines whether or not the determination frequency exceeds a predetermined threshold (for example, 5 times in 10 minutes). Then, when the determination frequency exceeds the predetermined threshold, the analysis unit 3 determines that these determinations were erroneous determinations associated with the increase in the consumption current of the load P. Therefore, the analysis unit 3 outputs a notification signal to change the threshold T1 of the frequency spectrum level at which insulation deterioration has occurred between the lines from the currently set threshold T1. In this case, based on the notification signal, for example, an announcement may be made from a speaker saying, "If you plan to continue using this load for a long period of time, please operate the setting unit to increase the determination threshold."

[0055] As described above, the insulation degradation determination device 1 acquires a noise signal between the first voltage line L1 and the neutral line N and a noise signal between the second voltage line L2 and the neutral line N, calculates frequency spectra of these noise signals, and determines whether insulation degradation has occurred based on the frequency spectra. This makes it easier to distinguish environmental factors (e.g., noise due to a load (electronic device)) that are less directly related to insulation degradation occurring between the lines from the noise signal, making it easier to capture the characteristics of noise components caused by insulation degradation. This makes it possible to accurately determine insulation degradation.

[0056] Here, it is conceivable to adopt a conventional configuration in which, for example, an RC circuit is connected between the voltage line and the neutral line, and when a noise current of a certain frequency or higher flows, the occurrence of the tracking phenomenon is detected at that voltage level. However, with such a configuration, continuous tracking noise must be generated in order to distinguish between noise caused by tracking and noise generated by a load (electronic device, etc.) connected to the electric circuit, and it takes time to make the distinction, which may lead to a fire.

[0057] In contrast, the present insulation deterioration determination device 1 determines the occurrence of insulation deterioration based on a frequency spectrum obtained by frequency analysis of a noise signal acquired between the lines using a fast Fourier transform, so that it is possible to capture noise characteristics in the early stages of insulation deterioration and detect abnormalities in insulation deterioration at an earlier stage.

[0058] Furthermore, the inventors have repeatedly studied frequency spectra calculated from noise signals and found that the band on the frequency axis where noise components caused by insulation deterioration between lines appear and their appearance intervals are characteristic. That is, as described above, it was found that noise components caused by insulation deterioration between lines appear prominently in the frequency band of 1 MHz to 3 MHz in the frequency spectrum, and that the noise level is high at a certain interval within the range of 300 KHz to 500 KHz on the frequency axis. This can be considered as follows.

[0059] For example, if an electrical outlet is left plugged in for a long time, dust accumulates between the outlet and the power plug, and when moisture is added to the dust, a carbonization path is formed between the blades of the power plug, and spark discharges are repeated in the carbonization path. Then, the carbonization range spreads to the inside, and eventually a strong discharge occurs from there, leading to ignition. The conductivity of the carbonization product generated in the carbonization path is high. Therefore, when commercial voltage is applied to the tip of the carbonization product, the electric field concentrates and sparks are generated. Then, the commercial harmonic noise generated at this time is superimposed on the line inside the outlet, and the harmonic noise is also superimposed on the line inside the distribution board through the line. As a result, the inventor discovered that the characteristic of the frequency spectrum when ignition occurs due to tracking is that it appears in the frequency band of 1 MHz to 3 MHz, and the noise level increases at regular intervals within the range of 300 KHz to 500 KHz on the frequency axis.

[0060] Therefore, in the insulation deterioration determination device 1, it is decided to determine whether or not insulation deterioration has occurred between the lines by utilizing periodic feature parts on the frequency axis that appear in the frequency spectrum. In this way, by capturing the periodic feature on the frequency axis that appears in the frequency spectrum as a feature of the noise component caused by insulation deterioration, it becomes possible to accurately determine the occurrence of insulation deterioration.

[0061] Moreover, according to the insulation deterioration determination device 1, when the level of the frequency spectrum exceeds the threshold value T1 (46 dBμV) in a frequency spectrum in the range of 1 MHz to 3 MHz, it is determined that insulation deterioration has occurred between the lines. This makes it possible to distinguish the influence of noise from the load P, which is represented by electronic devices, from noise signals on the lines, and makes it easier to grasp the characteristics of the noise components caused by insulation deterioration.

[0062] Furthermore, according to the insulation deterioration determination device 1, when the level of the frequency spectrum in the range of 1 MHz to 3 MHz exceeds the threshold T1 (46 dBμV) at intervals of, for example, 300 KHz to 500 KHz on the frequency axis, it is determined that insulation deterioration has occurred between the lines. This makes it possible to distinguish the influence of noise from the load P, such as electronic devices, from noise signals on the lines, making it easier to capture the characteristics of noise components caused by insulation deterioration.

[0063] Moreover, according to the insulation deterioration determination device 1, a first frequency spectrum calculated from a noise signal between the lines of the first voltage line L1 and the neutral line N is compared with a second frequency spectrum calculated from a noise signal between the lines of the second voltage line L2 and the neutral line N, and it is determined that insulation deterioration has occurred when the difference value between the two frequency spectra exceeds a threshold value T3 (for example, 5 dBμV). In the case of a single-phase three-wire system, it is relatively rare that insulation deterioration occurs simultaneously between the lines of the first voltage line L1 and the neutral line N and between the lines of the second voltage line L2 and the neutral line N. Therefore, by making a determination based on the difference value between the two frequency spectra as described above, it is possible to cancel environmental factors (for example, noise due to a load (electronic device)) that are less directly related to insulation deterioration occurring between the lines from the noise signal.

[0064] Moreover, according to the insulation degradation determination device 1, a comparison frequency spectrum calculated based on a test signal acquired in a test environment where no insulation degradation occurs between the lines is compared with a frequency spectrum calculated from a noise signal between the lines of the first voltage line L1 and the neutral line N or a frequency spectrum calculated from a noise signal between the lines of the second voltage line L2 and the neutral line N, and it is determined that insulation degradation has occurred when the difference value between the two frequency spectra exceeds a threshold value T4 (e.g., 10 dBμV). In this way, by comparing the level of the comparison frequency spectrum in a test environment where no insulation degradation occurs between the lines with the level of the frequency spectrum acquired during actual operation, it is possible to reduce environmental factors (e.g., noise due to a load (electronic device)) that have little direct relationship to insulation degradation occurring between the lines from the noise signal.

[0065] Furthermore, according to the insulation deterioration determination device 1, when the power consumption calculated from the current consumption of the load P measured by the current measurement unit 4 is equal to or less than the threshold value T2 of 0.4 KWh, it is determined whether or not insulation deterioration has occurred between the lines. This makes it possible to reduce erroneous determinations of the occurrence of insulation deterioration caused by the influence of noise from the load, such as electronic devices.

[0066] Furthermore, according to the insulation degradation determination device 1, if the current consumption of the load P measured by the current measurement unit 4 is on an upward trend, it is not determined whether insulation degradation has occurred between the lines. This makes it possible to reduce erroneous determinations of the occurrence of insulation degradation caused by the influence of noise from a load such as an electronic device.

[0067] Furthermore, the insulation deterioration determination device 1 can select and set in a stepwise manner a threshold value T1 for comparison with the level of a frequency spectrum calculated from a noise signal between lines, and a threshold value T2 for comparison with an amount of power consumption calculated from a current consumption measured by the current measurement unit 4. This makes it possible to select a predetermined threshold value taking into consideration the influence of loads such as electronic devices on the lines, thereby reducing erroneous determinations of insulation deterioration.

[0068] In addition, according to the insulation deterioration determination device 1, a noise signal can be acquired via a constant impedance circuit, so that the impedance on the insulation deterioration determination device 1 side is fixed when viewed from the load side, which is represented by electronic devices on the line, and therefore the fluctuation range of the noise components contained in the noise signal is reduced, thereby reducing erroneous determinations.

[0069] The present invention is not limited to the above-described embodiment, and can be freely modified, improved, etc. as appropriate. The material, shape, size, numerical value, form, number, location, etc. of each component in the above-described embodiment are arbitrary and not limited as long as the present invention can be achieved.

[0070] For example, in the above embodiment, the power distribution system is a single-phase three-wire system, but the power distribution system is not limited to this system. For example, the power distribution system may be a single-phase two-wire system or a three-phase three-wire system.

[0071] In the above embodiment, the insulation deterioration determination device is described as being incorporated in the distribution board, but the present invention is not limited to this. For example, the insulation deterioration determination device may be a device installed outside the distribution board, or may be a portable inspection device separated from the distribution board.

[0072] In the above embodiment, the insulation deterioration determination device is described as being incorporated in a distribution board installed in a typical home, but the present invention is not limited to this embodiment. For example, the insulation deterioration determination device may be incorporated in a distribution board installed in an office, a company, a factory, a commercial facility, or the like. [Explanation of symbols]

[0073] 1: insulation deterioration determination device, 2: acquisition unit, 3: analysis unit, 4: current measurement unit, 5: setting unit, 21: low-pass filter circuit, 22: oscillator, 23: frequency coupling unit, 24: band-pass filter circuit, 25: amplifier, 26: A / D conversion circuit, 31: memory unit, 32: comparison unit, 33: determination unit, B: breaker (circuit breaker), D: distribution board, L1: first voltage line, L2: second voltage line, N: voltage line, P: load (electronic device, etc.)

Claims

1. An acquisition unit for acquiring a noise signal on a line; an analysis unit that calculates a frequency spectrum, which is data on a frequency axis, using the noise signal and performs an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum; Equipped with the analysis unit performs an analysis to determine whether or not insulation deterioration has occurred between lines by utilizing periodic features appearing at regular intervals on the frequency axis in the frequency spectrum and based on the frequency spectrum within a predetermined frequency band. Insulation deterioration determination device.

2. the analysis unit determines that insulation deterioration has occurred between the lines when the level of the frequency spectrum exceeds a predetermined threshold value at regular intervals on the frequency axis within the predetermined frequency band; The insulation deterioration determination device according to claim 1 .

3. The constant interval is a value in the range of 300 KHz to 500 KHz. The insulation deterioration determination device according to claim 2 .

4. Further, a setting unit capable of selecting and setting the predetermined threshold value in a stepwise manner is provided. The insulation deterioration determination device according to claim 2 or 3.

5. The analysis unit is a storage unit that stores a comparison frequency spectrum calculated based on a test signal acquired in a test environment in which no insulation deterioration occurs between lines; a comparison unit that compares a level of the comparison frequency spectrum with a level of the frequency spectrum acquired by the acquisition unit; a determination unit that determines whether or not insulation deterioration has occurred between the lines based on a comparison result obtained by the comparison unit; having The insulation deterioration determination device according to claim 1 .

6. The line includes a first voltage line, a neutral line, and a second voltage line; the analysis unit compares a first frequency spectrum calculated from a noise signal between the first voltage line and the neutral line with a second frequency spectrum calculated from a noise signal between the second voltage line and the neutral line, and determines that insulation degradation has occurred when a difference value, which is a comparison result, exceeds a predetermined threshold value. The insulation deterioration determination device according to any one of claims 1 to 5.

7. moreover, A current measuring unit is provided for measuring a current consumption flowing on a line, the analysis unit performs an analysis to determine whether or not insulation deterioration has occurred between lines when the current consumption is equal to or less than a predetermined threshold value. The insulation deterioration determination device according to claim 1 .

8. moreover, A current measuring unit is provided for measuring a current consumption flowing on a line, the analysis unit does not perform an analysis to determine whether insulation deterioration has occurred between lines when the consumption current is on an upward trend; The insulation deterioration determination device according to claim 1 .

9. The acquisition unit has a constant impedance circuit and acquires a noise signal via the constant impedance circuit. The insulation deterioration determination device according to any one of claims 1 to 8.

10. An acquisition unit for acquiring a noise signal on a line; an analysis unit that calculates a frequency spectrum, which is data on a frequency axis, using the noise signal and performs an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum; Equipped with The line includes a first voltage line, a neutral line, and a second voltage line; the analysis unit compares a first frequency spectrum calculated from a noise signal between the first voltage line and the neutral line with a second frequency spectrum calculated from a noise signal between the second voltage line and the neutral line, and determines that insulation degradation has occurred when a difference value, which is a comparison result, exceeds a predetermined threshold value. Insulation deterioration determination device.

11. An acquisition step of acquiring a noise signal on a line; an analysis step of calculating a frequency spectrum, which is data on a frequency axis, using the noise signal, and performing an analysis to determine whether or not insulation deterioration has occurred between the lines based on the frequency spectrum; having the analysis step includes a determination step of determining whether or not insulation deterioration has occurred between lines based on periodic features at regular intervals on a frequency axis that appear in the frequency spectrum and on the frequency spectrum within a predetermined frequency band; Method for determining insulation deterioration.

12. An acquisition step of acquiring a noise signal on a line; an analysis step of calculating a frequency spectrum, which is data on a frequency axis, using the noise signal, and performing an analysis to determine whether or not insulation deterioration has occurred between lines based on the frequency spectrum within a predetermined frequency band; having The line includes a first voltage line, a neutral line, and a second voltage line; the analysis step includes a determination step of comparing a first frequency spectrum calculated from a noise signal between the first voltage line and the neutral line with a second frequency spectrum calculated from a noise signal between the second voltage line and the neutral line, and determining that insulation degradation has occurred when a difference value, which is a comparison result, exceeds a predetermined threshold value. Method for determining insulation deterioration.

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