WO2023281696A1 - 漏電センサおよび電路保護システム - Google Patents

漏電センサおよび電路保護システム Download PDF

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Publication number
WO2023281696A1
WO2023281696A1 PCT/JP2021/025779 JP2021025779W WO2023281696A1 WO 2023281696 A1 WO2023281696 A1 WO 2023281696A1 JP 2021025779 W JP2021025779 W JP 2021025779W WO 2023281696 A1 WO2023281696 A1 WO 2023281696A1
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Prior art keywords
excitation
output
circuit
current
magnetic
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Ceased
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PCT/JP2021/025779
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English (en)
French (fr)
Japanese (ja)
Inventor
俊彦 宮内
泰行 岡田
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to KR1020237039894A priority Critical patent/KR102794213B1/ko
Priority to CN202180099489.0A priority patent/CN117501139A/zh
Priority to DE112021007937.9T priority patent/DE112021007937T5/de
Priority to PCT/JP2021/025779 priority patent/WO2023281696A1/ja
Priority to JP2021564252A priority patent/JP7005824B1/ja
Publication of WO2023281696A1 publication Critical patent/WO2023281696A1/ja
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
    • G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/04—Measuring direction or magnitude of magnetic fields or magnetic flux using the flux-gate principle
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values

Definitions

  • This application relates to earth leakage sensors and circuit protection systems.
  • a fluxgate sensor is known as a minute current sensor for both AC and DC.
  • the magnetic core is alternately excited by a coil, and from the difference between the time when the core is magnetically saturated and the detection coil does not generate an output, and the time when the core is not saturated and the detection coil generates an output, The magnetic field to be measured, that is, the current value of the object to be measured is measured.
  • a ground leakage sensor using a fluxgate sensor secures high-speed response by setting the AC excitation frequency as high as several hundred Hz or more (see, for example, Patent Document 1).
  • the current measured by the leakage sensor using the fluxgate sensor is a two-phase or three-phase balanced current
  • two or three current wires to be measured pass through the magnetic core of the leakage sensor. Therefore, it is necessary to ensure that the inner diameter of the magnetic core of the earth leakage sensor is, for example, at least twice the diameter of the current wire to be measured. Furthermore, when the rated current of the current wire to be measured is large, the diameter of the current wire to be measured must be increased, and the inner diameter of the magnetic core must be increased. If the inner diameter of the magnetic core is increased, it is necessary to increase the cross-sectional area of the magnetic core in order to ensure the mechanical strength of the magnetic core. become
  • the present application has been made to solve the above-mentioned problems. Intended to provide a protection system.
  • An earth leakage sensor disclosed in the present application is an earth leakage sensor that detects an earth leakage in a current line to be measured, and includes a magnetic core through which the current line to be measured passes, an exciting coil wound around the magnetic core, a magnetic A detection coil wound around the body core, a magnetic sensor that detects the excitation magnetic field generated by the excitation coil, an oscillation circuit that generates an excitation signal whose fundamental frequency is the excitation frequency, the output of the magnetic sensor and the output of the oscillation circuit An excitation circuit that applies excitation current to the excitation coil based on the output of the oscillation circuit and the output of the unbalance judgment circuit, and an excitation frequency that is determined from the output voltage of the detection coil. and an output circuit that amplifies the output of the filter circuit.
  • the positive/negative asymmetry of the excitation magnetic field in the state where the balanced current is flowing in the current line to be measured is determined, and a control signal is generated. Either the positive or negative amplitude of is made smaller than the original magnitude, or the positive or negative offset current is superimposed on the excitation current.
  • the unbalance determination circuit determines that a balanced current flows in the current line to be measured from the excitation magnetic field and the excitation signal obtained from the magnetic sensor in a state where the balanced current is flowing in the current line to be measured. Based on the control signal, the excitation circuit reduces either the positive or negative amplitude of the excitation current to a smaller value than the original amplitude or the excitation current. Since either a positive or negative offset current is superimposed on the current, erroneous detection of electric leakage can be suppressed when a large current and a high frequency are required for the exciting current and the exciting magnetic field becomes asymmetrical between positive and negative.
  • FIG. 2 is a diagram showing the configuration of an earth leakage detector of the earth leakage sensor according to Embodiment 1;
  • FIG. 10 is a diagram for explaining the output voltage of the detection coil in a state in which no electrical leakage occurs;
  • FIG. 10 is a diagram for explaining an output voltage of a detection coil in a state where electric leakage is occurring;
  • FIG. 10 is a diagram for explaining a first example in which the positive and negative excitation magnetic fields are asymmetrical in a state in which no leakage occurs;
  • FIG. 10 is a diagram for explaining a second example in which the excitation magnetic field is positive and negative and asymmetrical in a state where no leakage occurs;
  • 1 is a diagram showing configurations of an earth leakage sensor and an electric circuit protection system according to Embodiment 1;
  • FIG. 4 is a flow chart for explaining the operation of the imbalance determination circuit according to the first embodiment; It is a figure which shows the result of having performed the fast Fourier transform with respect to the output signal of a magnetic sensor. It is a figure which shows the result of having performed the fast Fourier transform with respect to the output signal of a magnetic sensor.
  • FIG. 4 is a diagram showing the arrangement of magnetic sensors of the earth leakage sensor according to Embodiment 1;
  • FIG. 4 is a diagram showing the arrangement of magnetic sensors of the earth leakage sensor according to Embodiment 1;
  • FIG. 4 is a diagram showing the arrangement of magnetic sensors of the earth leakage sensor according to Embodiment 1;
  • FIG. 10 is a diagram showing the configuration of an earth leakage sensor and an electric circuit protection system according to Embodiment 2;
  • 9 is a flow chart for explaining the operation of the imbalance determination circuit according to the second embodiment;
  • FIG. 3 is a schematic diagram showing an example of hardware of an imbalance determination circuit according to Embodiments 1 and 2;
  • FIG. 1 is a diagram showing the configuration of an earth leakage detector 10 of an earth leakage sensor according to Embodiment 1.
  • the earth leakage detection unit 10 is a fluxgate sensor, and includes an annular magnetic core 11, an excitation coil 12 wound around the magnetic core 11, and a winding wound around the magnetic core 11.
  • a detection coil 13 is provided. Current measurement is performed by passing a current line to be measured, which is a measurement target, through the magnetic core 11 .
  • the winding of the excitation coil 12 and the winding of the detection coil 13 are wound only around a part of the magnetic core 11, but they are respectively wound around the entire circumference of the magnetic core 11. may
  • FIG. 2 is a diagram for explaining the output voltage of the detection coil 13 when a balanced current is flowing through the current line to be measured, that is, when no leakage occurs.
  • the upper left diagram in FIG. 2 is the magnetization curve of the magnetic core, that is, the BH curve, which is the change in magnetic flux density with respect to the applied magnetic field.
  • a voltage is generated in the detecting coil 13 while the magnetic core 11 is not magnetically saturated, and no voltage is generated while the magnetic core 11 is magnetically saturated. Since the magnetization curve of the magnetic material is symmetrical with respect to the origin, the state in which no voltage is generated in the detection coil 13 is repeated at twice the cycle of the excitation magnetic field when no leakage occurs.
  • Fig. 3 is a diagram for explaining the output voltage of the detection coil 13 in a state where an electric leakage occurs in the current line to be measured.
  • the dotted line indicates the value in the state where no electric leakage occurs
  • the solid line indicates the value in the state where electric leakage occurs.
  • the magnetic field due to the leakage is superimposed on the excitation magnetic field due to the occurrence of the leakage current
  • the upper right diagram of FIG. There is a difference in the time saturated with As a result, in the lower right diagram of FIG. 3, there is a difference between the time when the voltage is generated and the time when it is not generated.
  • the period of the time difference is twice the excitation frequency, and the time difference is proportional to the leakage current value.
  • the magnetic sensor detects the excitation magnetic field instead of the interlinking magnetic flux of the magnetic core 11 . Therefore, the output of the magnetic sensor has a waveform as shown in the lower left diagram of FIG.
  • FIG. 4 is a diagram for explaining a first case in which the positive and negative excitation magnetic fields are asymmetrical in a state in which no leakage occurs.
  • the dotted line indicates the value when the exciting magnetic field is positive and negative and symmetrical
  • the solid line indicates the value when the exciting magnetic field is positive and negative and asymmetrical.
  • the time for the core magnetic flux linkage to saturate on the negative side is shorter than the time for the core magnetic flux linkage to saturate on the positive side.
  • the time during which no voltage is generated in the detection coil 13 changes. Since the leakage is detected by detecting the difference between the time when the voltage is generated in the detection coil 13 and the time when the voltage is not generated, it is assumed that the leakage has occurred even though the leakage has not occurred. In other words, the asymmetry of the excitation magnetic field causes a measurement error of electric leakage.
  • FIG. 5 is a diagram for explaining a second example in which the positive and negative excitation magnetic fields are asymmetrical in a state in which a balanced current is flowing in the current line to be measured, that is, in a state in which no leakage occurs.
  • the dotted line indicates the value when the exciting magnetic field is positive and negative and symmetrical
  • the solid line indicates the value when the exciting magnetic field is positive and negative and asymmetrical.
  • the lower left diagram of FIG. 5 shows an example in which a positive offset is superimposed on the excitation magnetic field and the positive excitation magnetic field is saturated. This is the case, for example, when the positive excitation magnetic field is limited by the rated maximum value of the excitation power supply.
  • the core interlinking magnetic flux shown in the upper right diagram of FIG. 5 becomes the same as that shown in the upper right diagram of FIG. It will be the same as shown in the lower right figure. As a result, it is determined that an electric leakage current is occurring.
  • FIG. 6 is a diagram showing the configuration of the earth leakage sensor 1 and the circuit protection system according to Embodiment 1.
  • the leakage sensor 1 includes a magnetic core 11 , an exciting coil 12 , a detecting coil 13 , a magnetic sensor 14 , an imbalance determining circuit 15 , an exciting circuit 16 , an oscillator circuit 17 , a filter circuit 18 and an output circuit 19 .
  • a current wire 30 to be measured, which is an object to be measured by the leakage sensor 1 passes through the magnetic core 11 .
  • the oscillation circuit 17 generates an excitation signal having an excitation frequency as a fundamental frequency, and outputs the excitation signal to the excitation circuit 16 and the imbalance determination circuit 15 .
  • the filter circuit 18 acquires the excitation signal from the oscillation circuit 17, extracts the second harmonic component, which is the frequency component twice the excitation frequency, from the output voltage of the detection coil 13, and outputs it.
  • the second harmonic component which is the output of the filter circuit 18, corresponds to the difference between the time when the voltage of the detection coil 13 is generated and the time when it is not generated.
  • the output circuit 19 amplifies the output of the filter circuit 18 by a factor set according to the sensor rating and outputs it.
  • the magnification set according to the sensor rating is the sensor output per unit current and corresponds to the sensor sensitivity.
  • the electric circuit protection system includes an earth leakage sensor 1, a relay unit 20 and a protection circuit 21.
  • the relay unit 20 monitors the output of the output circuit 19 of the earth leakage sensor 1 to determine whether or not there is an earth leakage.
  • the current line 30 to be measured is cut off to protect the load equipment connected to the current line 30 to be measured from abnormalities in the electric circuit.
  • the relay unit 20 determines that an electric leak has occurred, for example, when the output of the output circuit 19 exceeds a predetermined threshold value.
  • the magnetic sensor 14 detects the exciting magnetic field generated by the exciting coil 12 .
  • the magnetic sensor may be, for example, a Hall element, a magnetoresistive effect element, a magneto-impedance element, or the like produced using a semiconductor process, or may be a coil capable of detecting an alternating magnetic field.
  • a factor that affects the excitation magnetic field is the uniformity of windings in the excitation coil.
  • the exciting coil 12 is a coil called a toroidal coil that winds toward the inside or outside of an annular core. If the winding is evenly wound, the magnetic flux generated by the exciting current is confined within the coil. is applied.
  • the leakage sensor 1 does not predict the excitation magnetic field from the excitation current, but detects the excitation magnetic field by the magnetic sensor 14 .
  • the imbalance determination circuit 15 determines whether there is a balanced current in the current line 30 to be measured based on the excitation signal from the oscillation circuit 17 and the excitation magnetic field obtained from the magnetic sensor 14 when the current line 30 to be measured has a balanced current.
  • a control signal is generated by determining the positive/negative asymmetry of the excitation magnetic field in the flowing state, and the generated control signal is output to the excitation circuit 16 .
  • the excitation circuit 16 Based on the output of the unbalance determination circuit 15, the excitation circuit 16 reduces the amplitude of either the positive or negative signal of the excitation current from its original magnitude, or offsets the excitation current to either the positive or the negative. As a result, the excitation magnetic field becomes positive and negative symmetrical.
  • the unbalance determination circuit 15 detects the current from the magnetic sensor 14 to the exciting coil in a state in which a balanced current is flowing through the current line 30 to be measured, that is, in a state in which a rated current is supplied to the current line 30 to be measured without leakage.
  • Information on the excitation magnetic field generated at 12 is acquired, and an excitation signal is acquired from the oscillation circuit 17 . Since the exciting magnetic field generated in the exciting coil 12 is a differential value of the exciting current generated from the exciting signal, the exciting signal and the exciting magnetic field have a phase difference of about 90 degrees.
  • the unbalance determination circuit 15 synchronously detects the signal of the excitation magnetic field with a signal obtained by shifting the phase of the excitation signal by 90 degrees, and determines the positive/negative asymmetry of the waveform of the excitation magnetic field. Since the frequency of the excitation magnetic field is uniquely determined by the excitation circuit 16, the unbalance determination circuit 15 performs Fourier transform on the output of the magnetic sensor 14 to determine the waveform distortion based on the intensity of harmonics other than the fundamental wave. , the positive and negative asymmetry of the waveform of the excitation magnetic field may be determined. It should be noted that the unbalance determination circuit 15 does not determine the positive/negative asymmetry of the waveform of the exciting magnetic field when the earth leakage sensor 1 is detecting the earth leakage.
  • the waveform of the excitation current output from the excitation circuit 16 is positive and negative, the waveform of the excitation magnetic field is positive and negative, as shown in the lower left diagram of FIG. be able to.
  • either the positive or negative value of the exciting current may be distorted due to the influence of power source noise of the exciting circuit 16, and the waveform of the exciting magnetic field may become asymmetrical between the positive and negative values.
  • the imbalance determination circuit 15 detects the asymmetry of the exciting magnetic field, it outputs a control signal corresponding to the positive/negative asymmetry of the exciting magnetic field to the exciting circuit 16.
  • the exciting circuit 16 determines whether the exciting current is positive or negative. Reduce the amplitude of the signal or offset the excitation current either positively or negatively. It should be noted that the excitation circuit 16 does not change the amount by which the amplitude of the excitation current is reduced and the amount of offset superimposed on the excitation current when the leakage sensor 1 is detecting a leakage.
  • FIG. 4 an example in which the unbalance determination circuit 15 detects that the magnitude of the negative magnetic field and the magnitude of the positive magnetic field of the excitation magnetic field are different as the asymmetry of the excitation magnetic field will be described.
  • the imbalance determination circuit 15 detects that the negative magnetic field of the excitation magnetic field has become smaller than the positive magnetic field as indicated by the solid line in the lower left diagram of FIG.
  • a control signal is output to the excitation circuit 16 to indicate that the positive amplitude of the excitation current should be made smaller than the original amplitude.
  • the excitation circuit 16 receives the control signal indicating that the positive amplitude of the exciting current is to be made smaller than the original amplitude, and makes the positive amplitude of the exciting current smaller than the original amplitude.
  • the unbalance determination circuit 15 confirms that the excitation magnetic field is symmetrical, the positive and negative symmetry of the excitation magnetic field is maintained by fixing the control amount in the excitation circuit 16 .
  • the unbalance determination circuit 15 detects that a positive offset is superimposed on the excitation magnetic field as the asymmetry of the excitation magnetic field
  • the imbalance determination circuit 15 outputs to the excitation circuit 16 a control signal indicating that a negative offset current should be superimposed on the excitation current.
  • the excitation circuit 16 receives the control signal indicating to superimpose the negative offset current on the excitation current, and superimposes the negative offset current on the excitation current, so that the excitation magnetic field becomes positive and negative symmetrical.
  • the unbalance determination circuit 15 confirms that the excitation magnetic field is symmetrical, the positive and negative symmetry of the excitation magnetic field is maintained by fixing the control amount in the excitation circuit 16 .
  • FIG. 7 is a flow chart for explaining the operation of the imbalance determination circuit 15 according to the first embodiment.
  • the imbalance determination circuit 15 acquires the output of the magnetic sensor 14 and the output of the oscillation circuit 17, and proceeds to step S02.
  • step S02 the imbalance determination circuit 15 acquires the positive amplitude and negative amplitude of the output of the magnetic sensor 14, and proceeds to step S03.
  • step S02 for example, the excitation frequency, which is the frequency of the excitation signal, is obtained from the output of the oscillation circuit 17 obtained in step S01. By obtaining the peak value on the negative side, the positive amplitude and negative amplitude of the output of the magnetic sensor 14 are obtained.
  • step S03 the imbalance determination circuit 15 determines whether the difference between the positive amplitude and the negative amplitude of the output of the magnetic sensor 14 is equal to or less than a threshold value. If the difference between the positive amplitude and the negative amplitude is equal to or less than the threshold, the process proceeds to step S07, and if the difference between the positive amplitude and the negative amplitude exceeds the threshold, the process proceeds to step S04.
  • step S04 the imbalance determination circuit 15 determines whether the positive amplitude of the output of the magnetic sensor 14 is greater than the negative amplitude. If the positive amplitude is greater than the negative amplitude, proceed to step S05, and if the positive amplitude is smaller than the negative amplitude, proceed to step S06.
  • step S05 the imbalance determination circuit 15 outputs to the excitation circuit 16 a control signal that makes the positive amplitude of the excitation current smaller than the original amplitude, and the process returns to step S01.
  • the exciting circuit 16 receives a control signal that reduces the positive amplitude of the exciting current from its original magnitude, and reduces the positive amplitude of the exciting current by a predetermined magnitude.
  • step S06 the imbalance determination circuit 15 outputs to the excitation circuit 16 a control signal that makes the negative amplitude of the excitation current smaller than the original amplitude, and the process returns to step S01.
  • the exciting circuit 16 receives a control signal that reduces the negative amplitude of the exciting current to a smaller magnitude than the original, and reduces the negative amplitude of the exciting current by a predetermined amount.
  • step S07 the imbalance determination circuit 15 performs fast Fourier transform, that is, FFT processing on the output signal of the magnetic sensor 14 for one cycle of the excitation signal, acquires the integer-order harmonics of the excitation frequency, and step S08.
  • step S08 the imbalance determination circuit 15 determines whether the magnitude of the specific order harmonic component of the integer-order harmonics obtained in step S07 is equal to or less than a threshold value. If the magnitude of the harmonic component of the specific order is below the threshold, the operation of the unbalance determination circuit 15 is terminated, and if the magnitude of the harmonic component of the specific order exceeds the threshold, the process proceeds to step S09.
  • FIG. 8 is a diagram showing the result of performing fast Fourier transform on the output signal of the magnetic sensor 14, and the lower left diagram of FIG. 5 in the second case where the excitation magnetic field shown in FIG. shows the result of performing a fast Fourier transform on the excitation magnetic field indicated by the solid line in .
  • FIG. 8 shows integer-order harmonics with respect to the excitation frequency of the output signal of the magnetic sensor 14 for one cycle of the excitation signal, obtained in step S07 of FIG.
  • the horizontal axis indicates the harmonic order
  • the vertical axis indicates the intensity of the harmonic at each harmonic order on a logarithmic axis.
  • step S08 it is possible to estimate the magnitude of the offset superimposed on the excitation magnetic field by determining whether the magnitude of any of the fifth or lower harmonic components is equal to or less than the threshold value.
  • FIG. 9 is a diagram showing the result of performing fast Fourier transform on the output signal of the magnetic sensor 14, and the lower left diagram of FIG. 4 in the first case where the excitation magnetic field shown in FIG. shows the result of performing a fast Fourier transform on the excitation magnetic field indicated by the solid line in .
  • the horizontal axis indicates the harmonic order
  • the vertical axis indicates the intensity of the harmonic at each harmonic order on a logarithmic axis.
  • black triangles indicate a case where the difference between the positive and negative amplitudes of the excitation magnetic field is large
  • white circles indicate a case where the difference between the positive and negative amplitudes of the excitation magnetic field is medium.
  • a black square indicates a case where the difference between the positive amplitude and the negative amplitude of the excitation magnetic field is small.
  • the excitation magnetic field is positive and negative and asymmetrical in FIG.
  • the harmonic intensity decrease monotonically depending on the magnitude of the difference from the amplitude of . Therefore, for example, in step S02 shown in FIG. 7, the Fourier transform is performed as shown in step S07, and in step S03, it is determined whether the harmonic intensity decreases monotonously and the harmonic intensity of a specific order is equal to or less than a threshold value.
  • the imbalance determination circuit 15 determines whether the positive amplitude of the output of the magnetic sensor 14 is greater than the negative amplitude. If the positive amplitude is greater than the negative amplitude, proceed to step S10, and if the positive amplitude is less than the negative amplitude, proceed to step S11. In step S10, the unbalance determination circuit 15 outputs to the excitation circuit 16 a control signal for superimposing a negative offset current on the excitation current, and the process returns to step S01. Upon receiving the control signal for superimposing a negative offset current on the excitation current, the excitation circuit 16 superimposes a predetermined amount of negative offset current on the excitation current.
  • step S11 the imbalance determination circuit 15 outputs to the excitation circuit 16 a control signal for superimposing a positive offset current on the excitation current, and the process returns to step S01.
  • the excitation circuit 16 Upon receiving the control signal for superimposing a positive offset current on the excitation current, the excitation circuit 16 superimposes a positive offset current of a predetermined magnitude on the excitation current.
  • steps S02 and S07 the output signal of the magnetic sensor 14 for one cycle of the excitation signal is processed.
  • a high-speed storage device may be provided to acquire the output signal of the magnetic sensor 14 for several cycles and process the averaged signal.
  • FIG. 10, 11 and 12 are diagrams showing the arrangement of the magnetic sensor 14 of the earth leakage sensor 1 according to Embodiment 1.
  • FIG. 10, 11 and 12 the detection coil 13 is omitted, and the magnetic core 11, excitation coil 12 and magnetic sensor 14 are shown.
  • the excitation coil 12 is a toroidal coil wound around the magnetic core 11 .
  • a toroidal coil does not leak the magnetic field to the outside of the coil.
  • the magnetic sensor 14 since the magnetic sensor 14 is provided between the magnetic core 11 and the exciting coil 12, the magnetic sensor 14 can detect the exciting magnetic field.
  • an opening is provided in a part of the magnetic core 11 so that the magnetic core 11 is exposed without being wound around the exciting coil 12, and the magnetic sensor 14 is provided in the opening. Since the magnetic field leaks at the opening of the toroidal coil, even if the space for arranging the magnetic sensor 14 cannot be secured between the magnetic core 11 and the excitation coil 12, the magnetic sensor can be arranged by providing the opening. and the excitation magnetic field can be detected.
  • the magnetic core 11 is partially provided with a notch to form a magnetic gap. Since the magnetic field induced in the magnetic core 11 by the exciting current concentrates and leaks in the notch portion which is the magnetic gap, the magnetic sensor 14 provided in the notch portion of the magnetic core 11 reduces the excitation magnetic field. can be detected. Since a larger magnetic field leaks as the interval between the cutouts becomes narrower, the excitation magnetic field can be accurately measured by making the interval between the cutouts narrower.
  • the earth leakage sensor 1 is an earth leakage sensor 1 that detects an earth leakage in the current line 30 to be measured, and includes the magnetic core 11 through which the current line 30 to be measured penetrates, and the magnetic core 11 11, a detection coil 13 wound around a magnetic core 11, a magnetic sensor 14 for detecting the excitation magnetic field generated from the excitation coil 12, and an excitation signal having an excitation frequency as a fundamental frequency. , an unbalance determination circuit 15 that generates and outputs a control signal from the output of the magnetic sensor 14 and the output of the oscillation circuit 17, and the output of the oscillation circuit 17 and the output of the unbalance determination circuit 15.
  • an excitation circuit 16 for applying an excitation current to the excitation coil 12, a filter circuit 18 for extracting a frequency component twice the excitation frequency from the output voltage of the detection coil 13, and an output circuit 19 for amplifying the output of the filter circuit.
  • the unbalance determination circuit 15 determines that a balanced current is flowing through the current line 30 under measurement based on the excitation magnetic field and the excitation signal obtained from the magnetic sensor 14 in a state where a balanced current is flowing through the current line 30 under measurement. Based on the control signal, the excitation circuit 16 reduces either the positive or negative amplitude of the excitation current to a smaller value than the original amplitude or reduces the excitation current.
  • FIG. 13 is a diagram showing configurations of an earth leakage sensor 1a and an electric circuit protection system according to the second embodiment.
  • the circuit 16a is provided, and the output circuit 19 is provided as the output circuit 19a.
  • Other configurations of the leakage sensor 1a according to the second embodiment are the same as those of the leakage sensor 1 according to the first embodiment.
  • the relay unit 20 and the protection circuit 21 are the same as in the first embodiment.
  • the excitation circuit 16 a applies an excitation current to the excitation coil 12 based on the excitation signal from the oscillation circuit 17 .
  • the unbalance determination circuit 15a determines whether the excitation magnetic field obtained from the magnetic sensor 14 is positive or negative asymmetrically in a state in which a balanced current is flowing in the current line 30 under measurement, that is, in a state in which no leakage occurs in the current line 30 under measurement. Asymmetry is determined, and a control signal corresponding to the determined asymmetry is output to the output circuit 19a.
  • the unbalance determination circuit 15a does not determine the asymmetry between the positive and negative sides of the waveform of the excitation magnetic field when the leakage sensor 1a is detecting leakage.
  • the output circuit 19a obtains a corrected output by correcting the output of the filter circuit 18 based on the control signal output from the imbalance determination circuit 15a, amplifies the corrected output by a factor set according to the sensor rating, and outputs the corrected output. do.
  • FIG. 14 is a flowchart for explaining the operation of the imbalance determination circuit 15a according to the second embodiment.
  • the imbalance determination circuit 15a acquires the output of the magnetic sensor 14 and the output of the oscillation circuit 17, and proceeds to steps S22 and S25.
  • the imbalance determination circuit 15a acquires the positive amplitude and negative amplitude of the output of the magnetic sensor 14, and proceeds to step S23.
  • the imbalance determination circuit 15a determines whether the difference between the positive amplitude and the negative amplitude of the output of the magnetic sensor 14 is equal to or less than a threshold value.
  • step S24 the imbalance determination circuit 15a generates a correction value for the output circuit 19a to correct the output of the filter circuit 18, and the process proceeds to step S28.
  • step S24 how the output of the output circuit 19a changes in accordance with the value of the difference between the positive amplitude and the negative amplitude of the output of the magnetic sensor 14 is measured in advance, and a correction for those changes is performed.
  • the correction value may be stored in a storage device, and the imbalance determination circuit 15a may read the correction value according to the magnitude of the difference between the positive amplitude and the negative amplitude from the storage device. Further, in step S24, the imbalance determination circuit 15a may generate a correction value that sets the output of the output circuit 19a to 0, for example.
  • step S25 the imbalance determination circuit 15a performs fast Fourier transform, that is, FFT processing on the output signal of the magnetic sensor 14 for one cycle of the excitation signal, obtains the integer-order harmonics with respect to the excitation frequency, and step S26. proceed to In step S26, the unbalance determination circuit 15a determines whether the magnitude of the specific order harmonic component of the integer order harmonics obtained in step S25 is equal to or less than a threshold value. If the magnitude of the harmonic component of the specific order is equal to or less than the threshold, the process proceeds to step S28, and if the magnitude of the harmonic component of the specific order exceeds the threshold, the process proceeds to step S27.
  • fast Fourier transform that is, FFT processing on the output signal of the magnetic sensor 14 for one cycle of the excitation signal
  • step S26 the unbalance determination circuit 15a determines whether the magnitude of the specific order harmonic component of the integer order harmonics obtained in step S25 is equal to or less than a threshold value. If the magnitude of the harmonic component of the specific order is equal to or less
  • step S27 the imbalance determination circuit 15a generates a correction value for the output circuit 19a to correct the output of the filter circuit 18, and the process proceeds to step S28.
  • step S27 how the output of the output circuit 19a changes in accordance with the value of the harmonic component of a specific order obtained by FFT-processing the output of the magnetic sensor 14 is measured in advance.
  • the correction value may be stored in a storage device, and the imbalance determination circuit 15a may read the correction value according to the magnitude of the harmonic component from the storage device. Further, in step S27, the imbalance determination circuit 15a may generate a correction value that sets the output of the output circuit 19a to 0, for example.
  • step S28 the imbalance determination circuit 15a checks whether a correction value has been generated in at least one of steps S24 and S27, and if a correction value has been generated, outputs the correction value as a control signal to the circuit. 19a to end the operation of the imbalance determination circuit 15a.
  • the output circuit 19a receives the control signal from the unbalance determination circuit 15a, obtains a corrected output by correcting the output of the filter circuit 18 based on the correction value, and amplifies the corrected output by a factor set according to the sensor rating. Output.
  • the output circuit 19a obtains a corrected output by, for example, adding a correction value to the output of the filter circuit 18 or multiplying the output of the filter circuit 18 by the correction value.
  • the earth leakage sensor 1a is an earth leakage sensor 1a that detects an earth leakage in the current line 30 to be measured, and includes the magnetic core 11 through which the current line 30 to be measured passes, and the magnetic core 11 11, a detection coil 13 wound around a magnetic core 11, a magnetic sensor 14 for detecting the excitation magnetic field generated from the excitation coil 12, and an excitation signal having an excitation frequency as a fundamental frequency.
  • an oscillating circuit 17 that generates an excitation current to the exciting coil 12 based on the output of the magnetic sensor 14 and the output of the oscillating circuit 17, and an imbalance determination circuit 15a that generates and outputs a control signal from the output of the oscillating circuit 17; , a filter circuit 18 for extracting a frequency component twice the excitation frequency from the output voltage of the detection coil 13, and an output circuit 19a for amplifying the output of the filter circuit.
  • the output circuit 19a Based on the control signal, the output circuit 19a corrects the output of the filter circuit 18 to obtain a corrected output, and amplifies and outputs the corrected output. It is possible to suppress erroneous detection of electric leakage when current and high frequency are required and the excitation magnetic field is positive and negative and asymmetrical.
  • FIG. 15 is a schematic diagram showing an example of hardware of the imbalance determination circuit 15 in the first embodiment and the imbalance determination circuit 15a in the second embodiment.
  • the unbalance determination circuits 15 and 15a are implemented by a processor 40 such as a CPU (Central Processing Unit) that executes programs stored in the memory 50.
  • FIG. Memory 50 is also used as a temporary storage device in each process executed by processor 40 .
  • a plurality of processing circuits may work together to perform the functions described above.
  • the above functions may be realized by dedicated hardware.
  • the dedicated hardware may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.
  • the processor 40 is a CPU, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc., or a combination thereof. It is a thing.
  • the memory 50 is, for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, non-volatile or volatile semiconductor memory such as EPROM (Erasable Programmable ROM), magnetic disk, optical disk, or a combination thereof. It is a thing.
  • RAM Random Access Memory
  • ROM Read Only Memory
  • flash memory non-volatile or volatile semiconductor memory such as EPROM (Erasable Programmable ROM), magnetic disk, optical disk, or a combination thereof. It is a thing.
  • Processor 40 and memory 50 are bussed together.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Measuring Magnetic Variables (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
PCT/JP2021/025779 2021-07-08 2021-07-08 漏電センサおよび電路保護システム Ceased WO2023281696A1 (ja)

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CN202180099489.0A CN117501139A (zh) 2021-07-08 2021-07-08 漏电传感器以及电路保护系统
DE112021007937.9T DE112021007937T5 (de) 2021-07-08 2021-07-08 Leckstromsensor und schutzsystem für einen elektrischen pfad
PCT/JP2021/025779 WO2023281696A1 (ja) 2021-07-08 2021-07-08 漏電センサおよび電路保護システム
JP2021564252A JP7005824B1 (ja) 2021-07-08 2021-07-08 漏電センサおよび電路保護システム

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JP7622894B1 (ja) 2024-07-04 2025-01-28 富士電機株式会社 電流検出装置、漏電遮断器及び漏電リレー

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JP7622894B1 (ja) 2024-07-04 2025-01-28 富士電機株式会社 電流検出装置、漏電遮断器及び漏電リレー
JP2026008081A (ja) * 2024-07-04 2026-01-19 富士電機株式会社 電流検出装置、漏電遮断器及び漏電リレー

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KR102794213B1 (ko) 2025-04-11
JPWO2023281696A1 (https=) 2023-01-12

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