JP2002345145A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce passing energy, miniaturize a circuit interrupter and contacts, and alleviate damage to a short-circuited portion, if load equipment is short-circuited, by accelerating determining a short circuit current. SOLUTION: Receiving a time series current signal, corresponding to the current of an alternating-current path sampled by an A/D converter, a FFT(fast Fourier transform computation) means 31 performs computation and analysis on the signal to convert the signal into a plurality of pieces of amplitude and intensity data for each frequency component. An average computing unit 32 computes the average of the analyzed amplitude and the intensity of the frequency components. Meanwhile, a reference average obtained from the FFT means 31 and the average computing unit 32, by passing a known reference current is stored in a reference value memory 33 in advance. If it turns out from comparison of the reference average and an average during actual energization that the reference average < the average during actual energization, a breaking command is issued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit breaker used for protecting a low-voltage circuit or the like, and more particularly to a circuit breaker for judging the necessity of interruption when an excessive current flows.

[0002]

2. Description of the Related Art FIG.
No. 24, a circuit configuration diagram of a conventional electronic circuit breaker, FIG. 14 is an operation characteristic diagram of the circuit breaker, FIG. 15 is a current waveform diagram at the time of instantaneous operation of the circuit breaker, and FIG. It is the figure which compared the current and the waveform of the short circuit current and the overcurrent. In the figure, 1 is an AC circuit, 2 is a switching contact, 3 is a current transformer for detecting the current of the AC circuit 1, 4 is a rectifier circuit, 5 is a burden circuit for converting to voltage, 6 is a diode, and 7 is each phase. A signal conversion circuit for converting a detected current into an average value and an effective value; an OR circuit for selecting a maximum signal from converted signals of each phase;
Reference numeral 9 denotes an A / D conversion circuit for converting the signal selected by the OR circuit 8 into a digital signal. Reference numeral 10 denotes a microcomputer, which compares a current value converted into a digital signal with a time limit characteristic by program processing. When a predetermined level is exceeded, a shutoff signal for shutting off the circuit breaker is output.

An instantaneous operation processing unit 11 includes a D / A conversion circuit 11a, a comparator 11b, and a time generation circuit 11c.
Consists of This cutoff signal can be used for long time operation, short time operation,
There is an instantaneous operation, a long time processing unit 10a, a short time processing unit 10b, and an instantaneous operation processing unit 11 controlled by the microcomputer 10.
The respective processing units determine the magnitude of the detected current of the corresponding AC circuit 1 and output a cutoff signal. Reference numeral 12 denotes a thyristor serving as a trigger circuit, and reference numeral 13 denotes a tripping coil. The thyristor 12 is turned on by the cutoff signal to operate an opening / closing mechanism (not shown) by the electromagnetic force of the tripping coil 13 to open / close the switching contact 2. To interrupt the current in the AC circuit 1. Reference numeral 14 denotes a power supply unit that supplies operating power of each unit including the microcomputer 10.

[0004] The interruption determination operation will be described. When the abnormal current of the AC circuit 1 is detected, the interruption is performed according to the timed operation corresponding to any of the long timed operation, the short timed operation, and the instantaneous operation of the operation characteristics shown in FIG. The part that is particularly improved in the present invention is the instantaneous operation, and the instantaneous operation will be described in detail. If the peak value of the detected current of any phase exceeds a predetermined value, the instantaneous operation processing unit 11 makes a determination and turns on the trigger circuit 12. The predetermined value for the trigger ON determination is set by the reference potential of the comparator 11b.

[0005]

Generally, in such a conventional device, the time from the start of the short-circuit current to the trigger ON can be shortened by lowering the predetermined value of the trigger ON determination of the detection current, but it is not so much. If it is low, an erroneous shut-off operation is performed due to an inrush current described later. Therefore, the reference potential of the comparator 11b is set to a level at which it can be determined that the current is a short-circuit current. Therefore, the time from the start of the short-circuit current to the trigger ON is 10 at the fastest.
It takes more than milliseconds. As shown in FIG. 15, the short-circuit current during this time is limited by an arc generated at the switching contact 2 or a current limiting mechanism provided separately to interrupt the current at the switching contact 2. Although the sum of the determination of the short-circuit current and the operation time of the switching mechanism is a short time of 10 to 20 milliseconds, the current passes through the arc-extinguishing device including the switching contact 2 of the AC current and the current limiting mechanism for current limiting. The energy exponentially increases as the time elapses, so that the arc energy generated between the contacts increases. A robust switching contact 2, an arc extinguishing device, and a current limiting mechanism that can withstand this duty were required. During this time, the energy of the current flowing through the short-circuit fault point is also large,
The damage of the short-circuit load device also increases.

Next, the exciting inrush current will be described. A transient excitation inrush current flows when the transformer is loaded with no load or when there is a sudden voltage change. This exciting inrush current depends on the applied voltage phase, but may exceed 10 times the full load current, and the decay time may be 1 second or more. When the transformer is connected as a load of the circuit breaker, a reference potential of the comparator 11b that does not cause the circuit breaker to malfunction by this inrush current is set.

For this reason, the cutoff determination time is at least 10 m.
Seconds needed. Therefore, at the time of occurrence of a short-circuit accident, a current of at least 20 ms flows, causing a problem that not only the arc extinguishing device and the switching contact 2 are damaged, but also the short-circuited portion of the load device is greatly damaged. For this reason, in a 60 Hz distribution system, about 1/16 of one cycle to secure
Judgment within about 1 ms is required. Therefore, FIG.
It is an object of the present invention to obtain a circuit breaker that automatically determines the difference between a normal overload current, an exciting inrush current, and a rising waveform at the time of a short circuit accident in about 1 ms as shown in FIG.

[0008]

(1) A circuit breaker according to a first aspect of the present invention comprises a current detecting means for detecting a current of an AC circuit, and a current signal detected by the current detecting means for a predetermined time. Sampling means for sampling each time to obtain time series data; Fourier transform operation means for performing Fourier transform operation on time series data of the current signal from the sampling means to obtain amplitude intensity data for each frequency component; Average value calculating means for calculating an average value of the amplitude intensity for each frequency component from the data; a reference value memory for storing a reference average value corresponding to each of the frequency components in advance; A first comparing means for outputting in accordance with a comparison between a reference average value for each predetermined frequency component of the frequency components and an average value at the time of actual energization for each frequency component; The output of the first comparison means is obtained by a cutoff command.

(2) A circuit breaker according to a second aspect of the present invention is a circuit breaker for detecting a current in an AC circuit, and sampling a current signal detected by the current detecting means at predetermined time intervals. Sampling means for obtaining series data; Fourier transform operation means for performing a Fourier transform operation on the time-series data of the current signal from the sampling means to obtain amplitude intensity data for each frequency component; and for each frequency component from the amplitude intensity data. Average value calculating means for calculating the average value of the amplitude intensities, a reference value memory in which a reference average value is stored in advance for each of the frequency components, and a predetermined frequency for each of the frequency components or for each of the frequency components. An average comparing means for comparing the reference average value for each component with the average value at the time of actual energization for each frequency component and patterning the comparison result; A reference pattern memory for storing a reference pattern corresponding to the pattern, and a second comparison means for outputting the reference pattern in accordance with a comparison between the reference pattern and a comparison result pattern at the time of actual energization. The output of the means is used as a cutoff command.

(3) A circuit breaker according to a third aspect of the present invention is a circuit breaker for detecting current of an AC circuit, and sampling a current signal detected by the current detecting means at predetermined time intervals. Sampling means for obtaining series data; Fourier transform operation means for performing a Fourier transform operation on the time-series data of the current signal from the sampling means to obtain amplitude intensity data for each frequency component; and for each frequency component from the amplitude intensity data. Average value calculating means for calculating the average value of the amplitude intensities of each of the frequency components, or comparing the reference average value of each of the frequency components or of each of the predetermined frequency components with the average value at the time of actual energization of each of the frequency components A pattern generating means for patterning a result, a reference pattern memory for storing a reference pattern corresponding to the comparison result pattern in advance, And a third comparing means for outputting response to a comparison between the turn and the comparison result patterns in the actual current,
The output of the third comparing means is used as a cutoff command.

(4) The circuit breaker according to a fourth aspect of the present invention is the circuit breaker according to any one of the first to third aspects, wherein the amplitude intensity for each frequency component obtained by the Fourier transform operation means is provided. A rapid rise calculating means for differentiating the data in chronological order and calculating the rise of the amplitude intensity; and a rise of the amplitude intensity of each of the differentiated frequency components, or a rise among the rises for a specific frequency. And means for instructing a cutoff command based on an AND condition between the output of the output means and the output of any one of the first, second, and third comparison means.

(5) A circuit breaker according to a fifth aspect of the present invention is a circuit breaker, comprising: a current detecting means for detecting a current in an AC circuit; and a current signal detected by the current detecting means being sampled at predetermined time intervals. Sampling means for obtaining series data; Fourier transform operation means for performing a Fourier transform operation on the time-series data of the current signal from the sampling means to obtain amplitude intensity data for each frequency component; and for each frequency component from the amplitude intensity data. Average value calculating means for calculating the average value of the amplitude intensities, and statistical value calculating means for calculating statistical values such as variance, skewness, and kurtosis for each frequency component using the average value of the amplitude intensities, A statistic pattern generating means for patterning the statistic for each frequency component or a statistic for each specific frequency component among the statistic values; and a reference corresponding to the statistic pattern in advance. A reference pattern memory to be to store the turn, in which a fourth comparison means for interruption command in response to the comparison of the statistical value pattern generated at the time of actual current and the reference pattern.

(6) A circuit breaker according to a sixth aspect of the present invention includes the respective means of the circuit breaker according to any one of the first to third aspects, and further includes the amplitude intensity calculated by the average value calculating means. Statistical value calculating means for calculating statistical values such as variance, skewness and kurtosis for each frequency component using an average value; and statistical values for each frequency component or statistics of a specific frequency component among the statistical values. Statistical value pattern generating means for patterning a value,
A reference pattern memory in which a reference pattern corresponding to the statistical value pattern is stored in advance; a fifth comparing means for outputting in accordance with a comparison between the reference pattern and a statistical value pattern at the time of actual energization; The output of the means and the first, second,
There is provided a means for instructing a cutoff on an AND condition with the output of any one of the third comparing means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 1 is a circuit configuration diagram of a circuit breaker according to Embodiment 1 of the present invention, FIG. 2 is a configuration block diagram of a high-speed instantaneous operation processing unit, FIG. 3 is a configuration diagram showing a detailed configuration of a short-circuit determination unit, and FIG. FIG. 5 is a diagram showing an example of a comparison pattern diagram, and FIG. 5 is a diagram showing a model of a Fourier transform operation of the present invention.

In the figure, reference numerals 1 to 14 are the same as those described in the conventional apparatus. Reference numeral 20 denotes a high-speed instantaneous operation processing unit, and reference numeral 15 denotes a high-speed microcomputer (high-speed CPU). The high-speed instantaneous operation processing unit 20 is provided separately from the ordinary arithmetic processing microcomputer 10 to control the high-speed instantaneous operation processing unit 20. High-speed CPU 15
If the processing capability of the microcomputer 10 is sufficient, the processing of the microcomputer 10 may be fetched and a single CPU may be used.

Reference numeral 21 denotes an OR of converted current signals of each phase.
A filter for passing an appropriate frequency band component of the maximum current waveform selected by the circuit 8, an amplifier 22 for amplifying the current waveform passing through the filter 21, and an amplifier 22 for
The current waveform amplified by is sampled at predetermined time intervals, A / D converted, and a plurality of time-series data Yi (i = 1, 2,
.. N) is an A / D converter (sampling means), and 30 is a short-circuit judging unit that outputs a shut-off command when a short circuit is judged based on the time-series data Yi by a judgment described later. 31 is a Fourier transform operation means (FFT means)
And the time-series data output from the A / D converter 23
Performs Fourier transform operation on the past short-time current waveform based on Yi. Although details of the arithmetic processing will be described later, the arithmetic result obtained by the FFT means 31 obtains M amplitude strengths which are continuous in time series for every j frequency components.

Reference numeral 32 denotes an averaging unit. The averaging unit 32 obtains an average value of the amplitude intensities from M data of each frequency component of the operation result of the FFT means 31. 33 is a reference value memory, which is a normal overload current (short time characteristic range)
The reference average value obtained from the average value of the amplitude intensities of the respective frequency components subjected to the Fourier transform operation when is input is stored in advance. The reference average value of the reference value memory 33 stores the average value of the intensity for each frequency component calculated by Fourier transform obtained by actually applying a known current in a short time characteristic region (15 to 20 times the rated current value). Use the one you let. The data for each frequency component subjected to the Fourier transform operation of the known short time characteristic region stored in the reference value memory 33 is actually supplied to a high-speed instantaneous operation processing unit having FFT means different from the high-speed instantaneous operation processing unit 20. The obtained data may be recorded on an external personal computer or the like, and may be stored in the high-speed CPU 15 by communication means or the like at the same time as writing the program.

Reference numeral 34 denotes an average comparator for comparing the output of the average calculator 32 corresponding to each frequency component with the reference average value stored in the reference value memory 33. This comparison is obtained as P (fn) = (average arithmetic unit output) / (reference average value) for each frequency component. The result is expressed as a numerical value. For example, if this is defined as “L” when P <1 and “0” when 1 <P <1.5, and “H” when P> 1.5, Patterning as shown in FIG. 4 can be performed. Further, it is also possible to provide only “L” and “H” for only the magnitude relation without providing “0”.

Reference numeral 35 denotes a pattern comparator, and 36 denotes a reference pattern memory, which compares the pattern of FIG. 4 obtained by the average comparator 34 for each frequency component with a reference pattern stored in the reference pattern memory 36 in advance. For example, if the number of "H" is larger than the reference pattern, it is determined that a short circuit has occurred, and a cutoff command is output. Also, if a specific one to three frequency components, which are generated by a sharp rise in the initial stage of the application of a large short-circuit fault current, are "H" in frequency components obtained by energization corresponding to an actual short-circuit current, a cutoff command is output. It may be. Here, the reason why “H” is set when P> 1.5 is to take into account a safety coefficient for preventing malfunction, and in an extreme case, if there is at least one “H”, a shutoff command is issued. You may make it output.

Next, the detailed operation of the Fourier transform operation in the FFT means 31 will be described with reference to FIG. First, the FFT means 31 outputs A / A corresponding to the current of the AC circuit 1.
The time series data Yi (i =
1, 2,... N) are selected as observation sections from the time series data Yi. This observation section is a range that goes back N sampling times from the latest sampling point. Next, time series data
Divide Yi (x) into appropriate numbers. The divided time-series data is called an observation short time section y in (x). The length of the observation short section is called the window width and the sampling number is R
It shall be the width length for each piece. The width of shifting along the time axis when dividing is called a time shift, and is the number of samplings L. The number M of the divided observation short time sections is M = (N / L) +1. To sample the observation short time interval y in (x), use y
Expand as in (x) = Yi (x). The conditions are x = (n-1) R / 2 to (n + 1) R / 2,
n = 0, 1, 2,... M −1

In the above expansion, each of the numerical values, N, L, and R may be the minimum value that can perform the Fourier transform in the shortest possible time.
As an example, if N = 4096, R = 1024, L = 512,
M is 9 and y i0 (x), y i1 (x), y i2
(x),... y i7 (x), y i8 (x) are obtained.

The obtained sampling sequence is represented by y i0 (x) = Yi (−512), Yi (−511), Yi (−510)... Yi (0),
Yi (1), Yi (2) ... Yi (509), Yi (510), Yi (511) y i1 (x) = Yi (0), Yi (1), Yi (2)・ Yi (512), Yi (51
3), Yi (514) ・ ・ ・ ・ ・ ・ ・ Yi (1021), Yi (1022), Yi (1033) ・ ・ ・ y i7 (x) = Yi (3072), Yi (3073), Yi (3074) ・・ ・ Yi (358
4), Yi (3585), Yi (3586) ... Yi (1021), Yi (1022), Yi (1
033) y i8 (x) = Yi (3584), Yi (3585), Yi (3586) ... Yi (409
6), Yi (4097), Yi (4098) ・ ・ ・ ・ Yi (4605), Yi (4606), Yi (4
607) By the way, in y i0 (x) and y i8 (x), Yi (−51
2) Since values of Yi (−1) and Yi (4096) to Yi (4607) do not exist, appropriate numerical values may be defined, and may be 0, for example.

Then, each observation short time section y in
Perform Fourier transform operation in (x). This Fourier transform calculates the following equation (1).

[0024]

(Equation 1)

Here, k = 0 to (S−1) S = R / 2 ω (x) is a window function, for example, Hammin
g window. ω (x) = 0.54−0.46 cos ｛2πx / (R−
1) x = 0 to (R-1)

The Fourier transform here is a Fourier transform having a resolution obtained by discretely sampling the Nyquist frequency 1/2 T hertz (Hz) into S samples. As described above, a space surrounded by the time axis and the frequency axis is formed. Equation (1) above
The following is an example of the deployment. φi0 (S−1) / 2ST, φi1 (S−1) / 2ST, φi2 (S−1) / 2ST,... φi8 (S−1) / 2ST φi0 (S−2) / 2ST, φi1 (S−2) / 2ST, φi2 (S−2) / 2ST,... φi8 (S−2) / 2ST... φi0 (1) / 2ST, φi1 (1) / 2ST, φi2 (1) / 2ST, ····· φi8 (1) / 2ST φi0 (0) / 2ST, φi1 (0) / 2ST, φi2 (0) / 2ST, ····· φi8 (0) / 2ST

Although the phase component and the amplitude component are obtained as a result of the Fourier transform, the present embodiment uses the amplitude component.
The magnitude of the amplitude analyzed for each of the frequencies f1, f2, f3... Fj is shown in M time series. This model is shown in FIG. Then, the data is processed into a format in which the strength of the time-series amplitude for each frequency component surrounded by the time axis and the frequency axis can be determined.
First, as the first determination format, the frequencies f1, f2, f
3... Calculate the average value of the strength for each fj. Average calculator 3
In 2, the average value (μ) is calculated for each frequency by the equation shown in equation (2).

[0028]

(Equation 2)

The calculated average value for each frequency is averaged with a reference average value (for example, an average value obtained by performing FFT processing at 15 to 30 times the rated current value) of the frequency stored in the reference value memory 33 in advance. The comparison pattern is generated by comparison with the comparator 34 as shown in FIG. If “determination reference pattern> comparison pattern” is obtained by comparing the generated comparison pattern with the determination reference pattern in the reference pattern memory 36, the process proceeds to the next sampling.

However, when "judgment reference pattern <comparison pattern", it is judged that an accident current has occurred, a cutoff command is issued, the tripping coil 13 and the switching mechanism are operated from the trigger circuit 12, and the switching contact 2 is opened. The current in the AC circuit 1 is cut off. Also, in order to clarify that a large current has flowed due to the accident, a signal indicating that an abnormality has occurred in a display device or a monitoring device (not shown) for monitoring the plant is output, and a series of processing is performed. finish.

As described above, the necessity of interruption is determined at high speed in accordance with the difference between the short-circuit current and the frequency component of the rising waveform in normal overload, and the interruption is made early with small passing energy. The arc extinguishing device and the switching contact of the vessel can be miniaturized. Further, when the load device is short-circuited, damage to the short-circuited portion can be reduced.

FIG. 6 shows a modification of this embodiment, in which only the calculated average value for each frequency or the average value for each predetermined frequency among the calculated average values for each frequency is extracted. Then, the average value and the reference average value are compared with the average comparator 34.
And, for example, calculate “(reference average value) − (average arithmetic unit output)” for each frequency. If there is at least one negative result in the calculation result, a cutoff command is issued. A shutoff command may be issued based on a plurality of positive and negative numbers as a result, or a shutoff command may be issued if there is a large negative number. Also, “(average arithmetic unit output) / (reference average value)” is calculated for each frequency, and if at least one of the calculation results is greater than “1”, a cutoff command is issued, or the number of numbers greater than “1”
Alternatively, if one or more of the division results are very large, a cutoff command may be issued.

FIG. 7 shows another modification of this embodiment. The pattern generator 43 generates a pattern for each frequency from an average value for each frequency calculated by the average calculator 32. Alternatively, only the average value for each predetermined frequency is extracted from the average value for each frequency calculated by the average calculator 32 to generate a pattern for each frequency. On the other hand, the pattern of the reference average value corresponding to the generated pattern is stored in the reference pattern memory 3.
6, and the pattern comparator 35 compares the two patterns, and sends a cutoff command according to the comparison result.

Embodiment 2 In the configuration of the first embodiment, a cutoff command is issued only when a current exceeding a predetermined reference average value or reference pattern is detected.
In order to prevent malfunctions, a safety factor is added to the reference average value or reference pattern. The burden on the arc device also remains large. Therefore, a second embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a diagram showing a configuration of a short circuit judging section according to the second embodiment of the present invention. In the figure, reference numerals 30 to 36 are the same as those described in the first embodiment. Reference numeral 37 denotes a rapid rise degree calculating means, 38 denotes a frequency specifying unit, and 39 denotes an AND condition determining unit. The rapid rise calculating means 37 calculates the rapid rising degree by differentiating the amplitude intensity for each frequency component calculated and analyzed by the FFT means 31 in a time series. That is, when the differential value of the rear part of the time series of a specific frequency component increases as a positive number within the sampling observation period, the frequency component is rapidly increasing, and the increase can be predicted from the current time at the next sampling timing. Also, when the differential value at the rear of the time series is negative, it can be understood that it is attenuating.

The fault short-circuit current waveform is the rated value of the circuit breaker,
Since the circuit constants such as the wire diameter of the AC circuit and the distance between the circuit breaker and the fault point are not uniform, of the frequency components of the Fourier-transformed fault short-circuit current, the frequency components related to the rapid increase in short-circuit current When the degree exceeds a predetermined value, a signal is output to the AND condition determination unit 39. The frequency component related to the rapid increase of the short-circuit current may be selected from a plurality of frequencies instead of a single frequency, and the average value of the rapid increase may be compared with a predetermined value. The predetermined value of the rapid rise and the target frequency to be selected and specified are stored in a part of the reference value memory 33 in advance. The AND condition determining unit 39 issues a cutoff command when there is a signal from both the frequency specifying unit 38 and the pattern comparator 35. When only one of the signals is used, the cutoff command is not issued.

Therefore, the shutoff command is issued under the AND condition with the rapid rise of the sampling time series.
The reference average value stored in the reference value memory 33 to be compared with the reference value 4 is generally set lower than that in the first embodiment, and the cutoff output is issued earlier in the comparison of the average values. The current increase / decrease is predicted based on the rapid rise of, and the necessity of the interruption operation is determined. Therefore, it is possible to prevent the erroneous shutoff operation while issuing the shutoff command earlier.

FIG. 9 shows a modification of this embodiment, in which a signal on the average value input side input to the AND condition determination section 39 receives an output from the average comparator 34. 1 corresponds to the output of the average comparator 34 in FIG.

FIG. 10 shows another modification of this embodiment, in which the signal on the average value input side input to the AND condition determination section 39 receives the output from the pattern comparator 35. This corresponds to the output of the pattern comparator 35 in FIG.

Embodiment 3 FIG. 11 is a diagram showing a configuration of a short-circuit determination unit according to Embodiment 3 of the present invention. In the figure, reference numerals 30 to 32, 36, and 38 are the same as those described in the second embodiment. Numeral 40 denotes a distributed arithmetic unit, and numeral 41 denotes a distributed pattern comparator. The distributed arithmetic unit 40 includes the FFT unit 31
The variance (α) of the amplitude intensity for each frequency component in the sampling observation period analyzed by the Fourier operation is calculated by the following equation (3). Since the variance calculation is performed based on the average value (μ) as shown in Expression (3), it is convenient to provide the variance calculation at a stage subsequent to the average calculator 32.

[0041]

(Equation 3)

The variance statistically indicates the degree of variation in the size of each data with respect to the average value, and the absolute value of the variance does not indicate the amplitude intensity for each frequency component. However, a specific frequency component among the frequency components included in the current waveform of the short-circuit current has little variation and small variance. In another specific frequency component, the dispersion is large and the dispersion is large. Therefore, frequency components related to the short-circuit current waveform are specified and patterned. The frequency component related to the short-circuit current is specified by the Fourier calculation analysis and the dispersion calculation of the actual conduction waveform 15 to 30 times the rated current as in the description of the first embodiment. The extracted and patterned dispersion is stored in the reference pattern memory 36 in advance. The specific frequency related to the extracted short-circuit current is also stored in the reference pattern memory 36 or the reference value memory 33.
In advance.

Next, the operation will be described. The A / D converted current signal of the AC circuit 1 is supplied to
Short-time Fourier transform is performed to obtain M amplitude intensities continuous in a time series for each of j frequency components. The average calculator 32 and the variance calculator 40 calculate the variance for each frequency component. The frequency specifying unit 38 selects a predetermined threshold value and a specific frequency related to the short-circuit current stored in the reference pattern memory 36 or the reference value memory 33 from the j frequency components, and patterns the dispersion value. . Then, when the distribution pattern comparator 41 determines that the patterns are the same as compared with the reference pattern in the reference pattern memory 36, a cutoff command is issued.

By making the Fourier-transformed data value a variance value by statistical processing, irregular elements can be eliminated and a more accurate pattern structure can be compared with the reference. The Fourier-transformed data value is further expressed by the following equation (4).
Also, as shown in Expression (5), the determination of the cutoff command issuance may be performed using a method in which the pattern is further refined by statistical processing such as skewness and kurtosis by n-th power averaging to remove irregular elements.

[0045]

(Equation 4)

[0046]

(Equation 5)

Where β is skewness, γ is kurtosis, α is variance, μ
Is the average

Embodiment 4 FIG. 12 is a configuration diagram showing a configuration of a short-circuit determination unit according to Embodiment 4 of the present invention. In the figure, 30 to 36 are the same as those in the first embodiment, and 38, 40, and 41 are the same as those in the second embodiment. Reference numeral 42 denotes an AND condition determination unit which issues a cutoff command when there is a signal from both the signal from the dispersion pattern comparator 41 and the signal from the average comparator 34 or the signal from the pattern comparator 35. When only one of the signals is used, the cutoff command is not issued.

When the Fourier-transformed data values described in the third embodiment are averaged to the n-th power and patterned to be compared with a reference pattern, the determination of the cutoff command issuance is made only by the distribution coincidence even with the minute current of the AC circuit 1. May be reached. Therefore, the average comparator 3 that determines the magnitude of the current in the AC circuit 1
By taking the AND condition with 4, the short circuit fault current can be more reliably detected and the electric circuit and the load equipment can be protected.

[0050]

According to the present invention, as described above, the FFT
Since the frequency component of the current waveform of the AC circuit is monitored by the means and the difference between the short-circuit current and the frequency component of the rising waveform during normal overload is compared, it is determined at a high speed whether or not the interruption is necessary. The arc extinguishing device and the switching contact can be downsized, and when the load device is short-circuited, damage to the short-circuited portion can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a circuit breaker according to the present invention.

FIG. 2 is a configuration block diagram of a high-speed instantaneous operation processing unit according to the present invention.

FIG. 3 is a detailed configuration diagram of a short-circuit determination unit according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of a comparative pattern diagram according to the first embodiment of the present invention;

FIG. 5 is a diagram showing a model of a Fourier transform operation of the present invention.

FIG. 6 is a detailed configuration diagram of another short-circuit determination unit according to the first embodiment of the present invention.

FIG. 7 is a detailed configuration diagram of another short-circuit determination unit according to the first embodiment of the present invention.

FIG. 8 is a configuration diagram of a short-circuit determination unit according to Embodiment 2 of the present invention.

FIG. 9 is a detailed configuration diagram of another short-circuit determination unit according to the second embodiment of the present invention.

FIG. 10 is a detailed configuration diagram of another short-circuit determination unit according to the second embodiment of the present invention.

FIG. 11 is a configuration diagram of a short-circuit determination unit according to Embodiment 3 of the present invention.

FIG. 12 is a configuration diagram of a short-circuit determination unit according to Embodiment 4 of the present invention.

FIG. 13 is a circuit configuration diagram of a conventional electronic circuit breaker.

FIG. 14 is an operation characteristic diagram of the circuit breaker.

FIG. 15 is a current waveform diagram during an instantaneous operation of the circuit breaker.

FIG. 16 is a diagram comparing waveforms of an exciting inrush current, a short-circuit current, and an overcurrent.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 AC circuit, 2 ON / OFF contact, 3 Current transformer (current detection means) 10 microcomputer 12 trigger circuit, 15 high-speed microcomputer (high-speed CPU) 20 high-speed instantaneous operation processing unit,
21 filter, 22 amplifier, 23 A / D
Converter 30 Short-circuit judging unit 31 Fourier transform operation means (F
FT means) 32 average calculator 33 reference value memory, 34 average comparator (average comparison means), 35 pattern comparator (pattern comparison means) 36 reference pattern memory, 37 rapid rise degree calculation means 38 frequency identification section (pattern generation means) ), 39
AND condition determination unit 40 distributed arithmetic unit (statistical value calculation unit) 41 distributed pattern comparator (comparison unit), 42 AND condition determination unit 43 pattern generator (pattern generation unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G004 AA02 AB02 BA03 BA04 DA01 DB01 DC01 DC04 DC14 5G030 XX00 YY13

Claims (6)

[Claims] 1. A current detecting means for detecting a current in an AC circuit, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals to obtain time-series data, and a current from the sampling means. Fourier transform operation means for performing Fourier transform operation on signal time-series data to obtain amplitude intensity data for each frequency component; average value operation means for calculating an average value of amplitude intensity for each frequency component from the amplitude intensity data; A reference value memory in which a reference average value corresponding to each of the above-mentioned frequency components is stored in advance, and a reference average value for each of the above-mentioned frequency components or a predetermined one of the above-mentioned frequency components and an actual value for each of the frequency components. A first comparing means for outputting in accordance with a comparison with the average value at the time of energization, wherein the output of the first comparing means is used as a cutoff command. vessel. 2. A current detecting means for detecting a current of an AC circuit, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals to obtain time-series data, and a current from the sampling means. Fourier transform operation means for performing Fourier transform operation on signal time-series data to obtain amplitude intensity data for each frequency component; average value operation means for calculating an average value of amplitude intensity for each frequency component from the amplitude intensity data; A reference value memory in which a reference average value for each frequency component is stored in advance; a reference average value for each frequency component, or a reference average value for each predetermined frequency component among the frequency components; Average comparison means for comparing the time average value and patterning the comparison result, and a reference pattern corresponding to the comparison result pattern are stored in advance. A reference pattern memory, and second comparing means for outputting in accordance with a comparison between the reference pattern and a comparison result pattern at the time of actual energization, wherein an output of the second comparing means is used as a cutoff command. Circuit breaker. 3. A current detecting means for detecting a current of an AC circuit, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals to obtain time-series data, and a current from the sampling means. Fourier transform operation means for performing Fourier transform operation on signal time-series data to obtain amplitude intensity data for each frequency component; average value operation means for calculating an average value of amplitude intensity for each frequency component from the amplitude intensity data; A pattern generating means for patterning a comparison result between a reference average value for each of the frequency components or a predetermined frequency component among the frequency components and an average value at the time of actual energization for each of the frequency components; Comparison between the reference pattern memory that stores the reference pattern corresponding to the pattern and the above-mentioned reference pattern and the comparison result pattern at the time of actual energization And a third comparing means for outputting a signal in response to the third command, wherein the output of the third comparing means is used as a cutoff command. 4. The circuit breaker according to claim 1, wherein the amplitude intensity data for each frequency component obtained by the Fourier transform operation means is differentiated in chronological order to determine the degree of increase of the amplitude intensity. Calculating means for calculating a rapid rise degree, means for outputting a rise degree of the amplitude intensity of each of the differentiated frequency components, or output means according to a rise degree for a specific frequency among the rise degrees; 2. A circuit breaker comprising means for instructing a disconnection in accordance with an AND condition with an output from one of the second and third comparison means. 5. A current detecting means for detecting a current of an AC circuit, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals to obtain time-series data, and a current from the sampling means. Fourier transform operation means for performing Fourier transform operation on signal time-series data to obtain amplitude intensity data for each frequency component; average value operation means for calculating an average value of amplitude intensity for each frequency component from the amplitude intensity data; Means for calculating statistical values such as variance, skewness and kurtosis for each frequency component using the average value of the amplitude intensities; and a statistical value for each frequency component or A statistical value pattern generating means for patterning a statistical value for each specific frequency component; and a reference pattern memory for storing a reference pattern corresponding to the statistical value pattern in advance. And a fourth comparing means for issuing a cutoff command in accordance with a comparison between the reference pattern and a statistical value pattern generated at the time of actual energization. 6. The variance / distortion for each frequency component using the means of the circuit breaker according to any one of claims 1 to 3, and using the average value of the amplitude intensities obtained by the average value calculation means. Statistical value calculating means for calculating statistical values such as degree and kurtosis; statistical value generating means for patterning the statistical value of each frequency component or a statistical value of a specific frequency component among the statistical values; A reference pattern memory for storing a reference pattern corresponding to the value pattern; a fifth comparing means for outputting in accordance with a comparison between the reference pattern and a statistical value pattern at the time of actual energization; Output and first
-A circuit breaker comprising means for instructing a disconnection with an output of one of the second and third comparison means under an AND condition.