JP2003098194A - Noncontact type voltage probe device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact type voltage probe device which minimizes the effect of stray capacity due to the state of probe surrounding and is stable and good repeatability. SOLUTION: The coaxial cylindrical external electrode 201B of the probe is connected to the earth side of a high input impedance voltage probe 203, and the probe has a connection conductor line or a connection terminal for earthing the coaxial cylindrical external electrode 201B. By this, the variation of sensitivity of the probe due to the variation of capacity between a cylindrical internal electrode 201A and a surrounding metal 230, and the effect of voltage of the surrounding cable 221 are suppressed. By putting a low inductance plastics or foaming material in between the cylindrical internal electrode 201A and the coaxial cylindrical external electrode 201B, the capacity between the electrodes 201A and 201B is reduced and the probe sensitivity can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type voltage probe apparatus, and more particularly, to a non-contact type voltage probe apparatus for identifying an electromagnetic interference wave intrusion route for searching an electromagnetic interference wave source and an electromagnetic interference wave search apparatus therefor. Type voltage probe device.

The method for identifying the electromagnetic interference wave intrusion route proposed by the present invention is used to solve the problem of EMC (Electromagnetic Compatibility) for electronic devices such as communication devices and information processing devices. By using the method for identifying the electromagnetic interference wave intrusion route of the present invention, it is possible to identify the intrusion route of the interference wave that enters the device, and it becomes possible to effectively prevent the interference wave and identify the interference wave source.
Help solve the problem. In particular, since the intrusion route of an electromagnetic interference wave, which conventionally depends on experience and knowledge, can be objectively determined by a physical quantity, even an inexperienced one can be easily executed.

[0003]

2. Description of the Related Art Information communication devices are being advanced in high density, high integration, large capacity, and low voltage with the progress of semiconductor technology. In addition, the number of connection cables connecting a plurality of devices and the device connection form are becoming more complicated. Therefore, a phenomenon has occurred in which a common mode electromagnetic interference wave generated by induction or the like is transmitted between the cable connected to the device and the ground and propagates through the cable into the device to cause a failure. Particularly, as the capacity increases, the social impact of one failure increases, and due to the low voltage drive, the failure easily occurs. The electromagnetic interference wave that propagates and propagates through this cable and the like is called a conductive interference wave, and it is an important issue to eliminate the device failure due to the conductive interference wave.

Here, the "IEEE Standard Dictionary of
According to “Electrical and Electronics Terms”, a common mode disturbance appears between the signal line and the common reference plane (ground), and the potentials on both sides of the propagation path are simultaneously and with respect to the common reference plane (ground). It is defined as an interfering wave that changes by the same amount.
The common mode voltage is an average value of voltages (including phases) that appear between each phase and a specified reference potential. The reference potential here is usually the ground potential or the potential of the housing. Differential mode voltage refers to the voltage appearing between two wires in a defined set of conductors.

In order to prevent such conductive interference waves, it is necessary to measure the voltage / current of the interference waves that enter the device and to accurately grasp the intrusion route and level. Also,
By identifying the source of the electromagnetic interference wave that is the cause of the device failure, it is possible to take effective measures and eliminate the cause.

In order to grasp the situation of malfunction due to the interference wave, it is necessary to measure the voltage / current of the interference wave in the service operating state. Therefore, a voltage probe that can easily and accurately measure a conductive disturbance wave that propagates through a cable, especially a common-mode voltage that is generated between it and the ground, and that does not affect communication signals in the operating state. Development is required, and as one method therefor, a non-contact type voltage probe utilizing electrostatic coupling with a cable is being studied. However, since the electrostatic coupling is used, there is a possibility that the sensitivity becomes unstable due to the position of the internal cable and the electrostatic capacitance generated between the cable and the surrounding metal body. In particular, the stray capacitance generated between the surrounding metal objects changes depending on the surrounding conditions. As a result, the sensitivity was greatly changed and the potential of the surrounding metal objects was easily affected.

FIG. 17 shows a conventional non-contact type voltage probe device.
It shows in (A). In the figure, reference numeral 201A is a cylindrical electrode, 202
Is a jig for fixing the cable, 203 is a high input impedance voltage probe, and 204 is a level meter. FIG. 17
As shown in (A), the cylindrical electrode 201A causes electrostatic coupling between the surrounding building rebar, the metal object 230, the cable 221, and the like. An equivalent circuit at this time when there is no influence of the surroundings is expressed as shown in FIG. At this time, the output voltage V _p from the probe 203 is given by the following equation.

[0008]

[Equation 1]

Where V is the voltage generated between the cable 20 and the ground, C is the capacitance between the cable 220 and the cylindrical electrode 201A, R _p is the input resistance of the high input impedance voltage probe 203, and C _p is the high input. The input capacitance of the impedance voltage probe 203.

Here, there are building rebars, a metal cabinet 205 grounded, and the like, and the cylindrical electrode 20 around them.
Let C _q be the capacitance with 1A. Another cable 2
If a voltage V _x is generated at 21 and the like and the cylindrical electrode 201A is coupled through the electrostatic capacitance C _x , an equivalent circuit is represented as shown in FIG. 17 (C). As can be seen from this equivalent circuit, the sensitivity changes depending on the electrostatic capacitances C _x and C _q , and the influence of the voltage V _x is included in the voltage V _p ′, which becomes a large error factor in the measurement of the voltage V.

[0011]

From the above-mentioned points, the following problems are pointed out as problems of the current non-contact type voltage probe device, and it is difficult to perform stable and reproducible voltage measurement.

(1) The stray capacitance values C _x and C _q change depending on the surroundings of the probe 203.
The sensitivity of changes.

(2) It is easily affected by the voltage generated in the surrounding metal object 230.

Conventionally, the method of current measurement using a current probe has been generally used for the measurement of the conducted interference wave which propagates through the cable and enters the device. However, where the interfering wave enters the device depends largely on the experience of the engineer, and it has been difficult to correctly identify the intrusion route. For example, even if you try to identify the intrusion route by comparing the magnitudes of the currents, the value of the current at the point of intrusion does not necessarily increase if resonance occurs, so the determination based on the magnitude is not possible. It is impossible. In addition, it is difficult to specify the direction of current flow other than direct current, and it has not been possible to measure the traveling direction of electromagnetic interference waves. Therefore, the determination of the intrusion route depends on the experience of the measurer, and the determination is often erroneous. Also, in that case, since the intrusion route was uncertain (inaccurate), it was difficult to find the source of the disturbing wave that is the cause.

On the other hand, in order to identify the path of the interfering wave, there is also a method of making a judgment by cutting the connected cables, but since it requires stopping the device or cutting the cables,
It was not possible to accurately measure the effect of the interference wave in the actual situation.

Further, when a plurality of interfering waves enter, it is impossible to separate each interfering wave to search the interfering wave source.

The present invention has been made in view of the above problems, and an object thereof is to minimize the influence of stray capacitance due to the circumstances around the probe and to provide a stable and reproducible non-contact voltage probe. To provide a device.

[0018]

In order to achieve such an object, the present invention provides a cylindrical inner electrode and an inner electrode surrounding the inner electrode. Coaxial coaxial external electrode arranged coaxially, a cable fixing member that is arranged inside the internal electrode and holds the non-measurement target cable by penetrating, and a high input impedance connected to the internal electrode. Voltage detection means,
Means for connecting the external electrode to the ground side of the voltage detecting means, the voltage detecting means being attached to the external electrode so as to reduce parasitic inductance or capacitance in a high frequency region, and the internal electrode and the external electrode. It is characterized in that a low dielectric constant material is arranged between the electrodes.

The invention described in claim 2 is the same as claim 1.
In the invention described in (3), a low dielectric constant plastic or foam material is arranged between the internal electrode and the external electrode.

The invention described in claim 3 is the same as that of claim 1.
Alternatively, the inner electrode, the outer electrode, and the cable fixing member may be composed of two half-cylindrical halves having an integral structure, and the two halves may be connected to the cable fixing member. It is characterized in that the cable can be sandwiched inside and can be electrically and mechanically coupled.

The invention according to claim 4 is the same as claim 3
In the invention described in (3), the portions forming the internal electrodes and the portions forming the external electrodes in the two halves are connected by a conductor wire that can withstand repeated bending.

The invention described in claim 5 is the same as claim 3
Alternatively, in the invention described in (4), the two halves are electrically and mechanically coupled by a hinge or an electrical contact.

The invention described in claim 6 is the same as claim 1.
The invention according to any one of claims 1 to 5 is characterized in that the voltage detection means is a high input impedance voltage probe having an active element.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. [Embodiment 1] FIG. 1 is a diagram showing an embodiment of the present invention when an electromagnetic interference wave enters an electronic device. In the figure, reference numerals 1 and 2 denote electronic devices, and reference numerals 3, 4, 5, 6, and 7 denote cables connected to the electronic devices 1 and 2. Reference numeral 8 represents an electromagnetic interference wave induction source, and 9a represents the induced electromagnetic interference wave. Further, 9b, 9c and 9d are interfering waves that pass through the device 2 and exit. Reference numeral 10 represents a current probe, and when the current flows in the direction of the arrow inside, a positive voltage causes a disturbance voltage
It is output to the measuring device 23 side for current measurement.

Reference numeral 11 represents a voltage probe. In this embodiment, both probes 10 and 11 are of non-contact type. In particular, as will be described later with reference to FIG. 18, the voltage probe 11 uses a non-contact type voltage probe that has a cylindrical electrode and detects a voltage by electrostatic coupling so that measurement can be performed in the operating state of the device. did. As shown
The interfering wave 9a guided from the induction source 8 to the cables 6 propagates in the common mode between the cables 6 and the ground, and travels toward the electronic devices 1 and 2.

When the interfering wave 9a enters the electronic devices 1 and 2, the electronic circuits in the electronic devices 1 and 2 are affected and the electronic devices 1 and 2 malfunction. The intruding wave is
Other cables 5,4,7 connected to the electronics 1,2
Then, the interfering waves 9b, 9c and 9d are emitted from. If the intrusion route is determined based on only the magnitude of the current from the measurement with the conventional current probe, for example, when resonance occurs in the cables 4 in the figure, the magnitude of the current is higher than that of the cables 6 Class 4 becomes larger, and an incorrect intrusion route is specified.

However, in the present invention, the interfering waves 9a-9
By measuring the voltage / current of d with the measuring device 23 and determining the energy, it is possible to know the direction of energy flow and the traveling direction of the interfering wave. Further, even at the time of resonance, the energy does not increase from the energy storage side, so that the influence can be eliminated. The measuring device 23 can be configured, for example, in the same manner as the interference wave searching apparatus 101 shown in FIG. 11 described later.

FIG. 2 is a diagram showing a further concrete example in the case of the embodiment shown in FIG. In this specific example, the disturbance wave voltage and current in the time domain were measured, the measured voltage and current were Fourier transformed, and then the disturbance wave energy, that is, the power was calculated.

In FIG. 2, reference numeral 12 is a main unit of a small-sized communication device, 13 is an applying device for applying an interfering wave to a common cable, 14 and 15 are communication terminals, 16, 17 and 1.
Reference numeral 8 is a communication cable, and 19 is a power cable.
Further, 20 is an acrylic plate used to float the apparatus from the ground, and 21 is a copper plate for grounding.
Reference numeral 22 is an interfering wave generator, and 23 is a measuring instrument for measuring the interfering wave voltage / current and the interfering wave energy. For example, a digital oscilloscope capable of recording the waveform of the interfering wave and a control calculation device (computer) are provided. It is a combination.

FIG. 8 shows steps S1 to S10 of the overall flow of the method for identifying the interfering wave intrusion route in the above-described embodiment.
FIG.

As shown in FIG. 2, the interfering wave generated from the interfering wave generator 22 is applied from the applying device 13 through the communication cable 17 to the copper plate 21 in the direction of the main device 12 (common mode). That is, in this embodiment, the case where the interfering wave intrusion cable is the communication cable 17 is simulated. The current probe 10 and the voltage probe 11 are installed on the cables 17, 18 and 19 so that the direction in which the current flows into the main device 12 is positive (S1).

The common mode voltage and current waveforms of the communication cables 17, 18 and the power cable 19 are detected by the current probe 10 and the voltage probe 11 installed on each cable 17, 18, 19 and the voltage and current are measured by a measuring instrument. It is supplied to the 23 digital oscilloscope and shown in FIG.
Energy was calculated according to the processing of steps S2 to S5. According to the setting of the direction of the current, the direction of energy flow has a positive value in the direction of flow into the main device 12, and a negative value in the direction of flow out of the main device 12.

The current / voltage measurement results in the frequency domain, that is, the frequencies of the interfering waves are set to 10, 50, 100, 500,
The measurement result when a sine wave of 1000 kHz is shown in FIG. 3, and the result of calculating the energy from these is shown in FIG. From the measurement results of FIG. 3, the values of the current and the voltage are not always the maximum values of the communication cable 17, which is the intrusion route, and it is difficult to identify the intrusion route from these results.

Next, paying attention to the energy flow of the interfering wave, its value is calculated. First, in the case of a sine wave signal of a single frequency, the effective component of its energy (power) is calculated by the following formula.

[0035]

[Equation 2]

Here, V and I are the voltage and current of the interfering wave, and V ^* and I ^* are their complex conjugates.

Interference is usually not a single frequency sine wave,
It contains various frequency components. Therefore, step S2
The disturbance wave voltage and current waveforms measured in the time domain are converted into frequency domain data by Fourier transform (FFT) (S3). The result of the Fourier transform represents the contribution of each frequency to the measured voltage and current of the interference wave and its phase. Since the calculated value of energy is zero between voltage and current of different frequencies, the energy of the disturbing wave is represented by the sum of the energy calculated for each frequency constituting the disturbing wave. Therefore, the energy of the arbitrary waveform can be calculated by the following formula.

[0038]

[Equation 3]

Here, V (ω _i ) and I (ω _i ) are respectively complex Fourier transform components calculated from the waveforms of the measured voltage v (t) and current i (t), and ^* is its complex conjugate. Is represented. From the measurement data of each cable (3)
By calculating the energy of the interfering wave propagating through each cable by using the formula and determining the magnitude and the propagation direction, it becomes possible to grasp the energy flow of the interfering wave.

The calculation procedure is shown below.

1) The measured disturbance voltage and current waveforms are transformed from the time domain to the frequency domain by Fourier transform (FFT) (S3).

2) Correct the characteristics of the probe (S4),
The effective component of the measured energy of each cable is calculated using the equation (3) (S5).

3) Energy takes a positive or negative value depending on the setting of the current direction. That is, in step S6, if the calculated energy sign is positive (+), the energy propagation direction becomes the same as the current probe setting direction, and the process proceeds to step S7, where the calculated energy sign is negative (-). If so, the energy propagation direction is opposite to the current probe setting direction, and the process proceeds to step S8. In the next step S9, the magnitude of the sign and the calculated energy is compared. In the next step S10, the intrusion route of the interfering wave is specified based on the result of the size comparison. That is, the path having the maximum energy and the energy propagation direction entering the device is determined as the intrusion path.

From the result of calculation of the measured waveform data, the sign of the calculated energy has a positive value,
Only in the case of the communication cable 17. From the setting of the current direction, it can be said that the intrusion route of the interfering wave is from the communication cable 17, which coincides with the application direction in the actual measurement system. Therefore, it was shown that the method of the present invention can identify the intrusion route of the interfering wave. [Embodiment 2] Of the present invention, particularly continuous wave (Continuous W)
FIG. 5 shows an example considered to be effective for ave). In the figure, those parts that are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted. In the present embodiment, the absolute value and phase difference of the interfering wave voltage and current in the frequency domain are measured, and the energy of the interfering wave is calculated from the measurement result. Therefore, in this embodiment, a device capable of measuring the phase difference, such as a vector voltmeter or a network analyzer, is used instead of the measuring device 23 shown in FIG. In this embodiment 24,
25, 26, and 27 are vector voltmeters. The effective component of the energy of the interfering wave can be calculated from the absolute values of the voltage and current of the measured electromagnetic interfering wave and the phase difference by using the equation (3), and the intrusion route of the interfering wave can be specified from the result. It will be possible.

The flow of the method of identifying the interfering wave intrusion route in this embodiment is the same as the flow chart of FIG. 8 except that step S3 is omitted. [Embodiment 3] In this embodiment, an impulsive interfering wave (Im
Examples that are effective for pulsive inteference waves) will be shown. As a method of directly obtaining the energy, as shown in FIG. 6, there is a method of measuring a current / voltage waveform at a time when an interfering wave is generated and obtaining an integrated value.
The integral value is calculated by using an analog circuit,
Sampling and from that value,

[0046]

[Equation 4]

There is a method of calculating with. Example 3 is shown in FIG. In the figure, those parts that are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted. FIG. 9 shows the overall flow S1 to S5 of the method for identifying the interfering wave penetration route in this embodiment. In this embodiment, a probe 28 having a combination of a voltage / current measuring unit and an energy integrating circuit is attached (S1), and energy (electric power) is taken out by this probe 28, 29,3.
The energy (power) of the interfering wave of each cable is directly measured by the power measuring device of 0, 31, 32 (S2). The propagation direction of energy is determined from the sign of the measured (or calculated) energy (S3), and the magnitude of the measured (or calculated) energy is compared (S4) to identify the intrusion route of the interfering wave (S5). ) Is possible. In other words, the path having the maximum energy and the energy propagation direction entering the device is determined as the intrusion path.

Even in the case of a single disturbance wave such as an impulse disturbance wave, it is of course possible to calculate the power in the frequency domain and specify the propagation direction from the frequency spectrum instead of integrating in the time domain. is there. [Embodiment 4] Next, by capturing the energy flows of a plurality of interfering waves propagating through a cable connected to the device and displaying the positive and negative magnitudes of the energy in each frequency component, the plurality of interfering waves can be detected. FIG. 10, an embodiment in which it is possible to separate and search the intrusion direction of the interfering wave corresponding to each frequency component
This is shown in FIGS. 11 and 12.

FIG. 10 shows an example of usage of the apparatus of the fourth embodiment. In the figure, reference numeral 101 is an electromagnetic interference wave search device, and 102 is a probe device for voltage measurement.
It is a non-contact type voltage probe device as shown in FIG. 10
Reference numeral 3 is a probe device for measuring current, for example, an electromagnetic coupling type non-contact type current probe. By using such a non-contact type probe, the voltage and current of the interfering wave can be measured while keeping the device in a steady state. 10
Reference numeral 4 represents a cable in which an interfering wave is generated.

FIG. 11 is a block diagram showing the structure of the interference wave search apparatus shown in FIG. The arrows in the figure represent the data flow of the measured signal. The voltage and current waveforms of the interfering wave signal in the time domain are measured by the probe devices 102 and 103, respectively. The voltage waveform and the current waveform of the disturbing wave in the time domain are supplied to the measuring unit 111 to obtain AD-converted measurement data. Digital data indicating the voltage waveform / current waveform obtained by the measurement unit 111 is recorded in the recording device 112, and the calculation unit 113 calculates the energy for each frequency component of the interference wave from the data recorded in the recording device 112. The calculated energy and the measured voltage waveform and current waveform are displayed by the display unit 114. In this case, the positive / negative and magnitude of the energy for each frequency component are displayed on a screen having coordinates indicating the frequency.

Reference numeral 115 indicates each unit 111 to 111 of the apparatus 101.
A CPU that controls 114. In FIG. 11, the voltage probe device 102 and the current probe device 103 are
For example, like the voltage probe 10 and the current probe 11 shown in FIG. 1, a plurality of voltage probes and current probes arranged in a plurality of cables are colleced respectively.
tively. The measuring device 2 shown in FIG.
3 can also be configured as shown in FIG.

The propagation direction of the interfering wave is determined by the following procedure under the control of the CPU 115. (A) The probes 102 and 103 measure the voltage and current of the interfering wave signal in the time domain, and the measurement outputs are converted into digital data by the measuring unit 111. (B) The calculator 113 converts the data indicating the waveforms of the interfering wave voltage and current from the time domain data to the frequency domain data.

(C) The probe 10 is operated by the arithmetic unit 113.
After correcting the characteristics of 2 and 103, the measured energy of each cable is calculated for each frequency component. (D) For the calculation unit 113, the direction of current flow is determined in advance, and the energy takes a positive or negative value depending on the setting of the current direction. The code and the calculated energy level are displayed on the display unit 114 or the like.

(E) The propagation direction of the interfering wave is visually identified from the displayed result. Alternatively, from the sign indicating the direction of energy obtained in (d) and the magnitude of energy, the CPU
Determines the propagation direction of the interfering wave.

Here, the display of the energy of the interfering wave on the display unit 114 of the item (d) is as shown in FIG. 12, for example, in which the horizontal axis shows the frequency and the vertical axis shows the sign. Energy included (Power)
Is represented. Generally, a plurality of interference waves have individual frequency spectra, so that a plurality of interference waves can be identified by analyzing the frequency spectrum. By displaying energy in the frequency domain, for example, even if two interfering waves are invading from different paths, they can be separated by paying attention to the frequency components, and the intruding paths of the two interfering waves can be separated. Can be specified. In addition, a value (total power) obtained by adding energy of each frequency component can be displayed on the upper part of the display. In the example of FIG. 12, at least 1 is set on the positive side and the negative side.
You can see that there is likely to be an interfering wave.

That is, the effective component of the energy of the propagating interference wave is calculated from the voltage and the current of the electromagnetic interference wave generated in the cables, and the propagation direction of the electromagnetic interference wave is determined from the magnitude of the energy and the flowing direction of the energy. In the specified electromagnetic interference wave measuring method, the waveform of the interference wave voltage and current in the time domain is measured, and the measured voltage waveform v (t)
And the current waveform i (t) is converted from the time domain to the frequency domain, each frequency component of the interference wave is obtained, and the effective component of the energy of each frequency component is calculated to separate the plurality of interference waves. Then, the propagation direction of each interference wave is specified.

As described above, by measuring the voltages and currents flowing through a plurality of cables and calculating the effective energy of a plurality of disturbing waves from the waveforms, the disturbing waves are separated to facilitate the propagation direction of the disturbing waves. Can be specified. By being able to easily specify the propagation direction using the device of the present invention, the following effects can be obtained.

A. The source of the interfering wave can be easily identified and the cause can be removed. B. Since the propagation direction of the interfering wave becomes clear, it becomes possible to take effective measures. C. Since it focuses on the effective energy, it is not affected by resonance.

D. By evaluating the energy in the frequency domain, it is possible to separate the interfering waves of a plurality of different frequency components and specify the intrusion route of the interfering waves. E. By measuring the voltage and current of the interfering wave without contact, the propagation direction of the interfering wave can be specified in the operating state without stopping the device.

As described above, according to the fourth embodiment, the behavior of the interfering wave is accurately grasped while maintaining the device in the operating state, and the propagation direction of the electromagnetic interfering wave is quantitatively specified by the physical quantity. Also, it is possible to separate and probe a plurality of interfering waves. [Fifth Embodiment] A fifth embodiment is a more detailed example of the first embodiment for determining an intrusion route of an interfering wave according to the procedure shown in FIG. 8, and uses a configuration similar to that shown in FIG.
The entire process is controlled by 15. Flow charts for energy calculation of Example 5 are shown in FIGS. 13 and 14.

In FIG. 13, steps S1 to S5 are the same as those in FIG. 8, and the description thereof will be omitted. Step S
At 6, it is determined whether the measured number of cables has reached the total number of cables n. When the energy is calculated for all n cables, the process proceeds to the next steps S7 and S8 shown in FIG. The magnitude of energy here is evaluated by the total of each frequency component.

In FIG. 14, in step S7,
Determine the sign of the energy of each cable. Here, if the polarity of the current probe is set so that a positive value appears when the current of the interfering wave flows in the direction of entering the device, and if the energy is positive, the propagation direction of the energy is the direction of entering the device. On the contrary, if the energy is negative, it is determined that the propagation direction of energy is a direction away from the device.

In step S8, the energy levels of the cables are compared. For that purpose, first, the energy is normalized by the maximum value. Threshold Pt
To set. Next, the energy exceeding the threshold Pt is referred to as a large value. Energy below the threshold Pt is referred to as a small value.

In the next step S9, step S
7 and S8, the signs and magnitudes of the energy are shown in Cases 1 to Cas shown in FIGS.
Classify as any of e10. If Case 1 or 4, the process proceeds to step S10. In Case 6, the process proceeds to step S11. If Case 2 or 5, the process proceeds to step S12. If Case 3, 7, 8, 9 or 10, the process proceeds to step S13. In FIGS. 15A to 15J, 1, 2, ..., N denote cable numbers.

These Cases 1 to 10 are summarized in Table 1 below.

[0066]

[Table 1]

In the case of steps S10, S11 and S12, the following steps S14, S15 and S are performed respectively.
At 16, the cable with the positive sign and the largest size is identified. In step S17, step S1
The cable number specified in 4 is output in the form of display or print. In step S18, the cable number specified in step S15 is output, and a warning "a negative value is larger than a positive value" is also output. Step S19
Then, the number of the cable specified in step S16 is output, and the warning "need to check each cable interval of a plurality of cables" is also output. The reason is that if the cable intervals are close, it is necessary to check the cable intervals, because interference waves may be induced from the same interference source to multiple cables.

In the case of step S13, in the next step S20, an instruction that the propagation direction of the interfering wave cannot be specified and that re-measurement is performed is output.

[Sixth Embodiment] FIG. 16 shows an example of a more specific determination procedure in the frequency domain of the fourth embodiment for identifying the intrusion routes of a plurality of interfering waves. When the energy is calculated for each frequency after the processing up to step S4 in FIG. 13 is completed, the process proceeds to step S1 in FIG. In this step S1, the energy for each frequency is calculated by the illustrated formula. In the next step S2, the process shown in FIG. 14 is performed on the frequency spectrum indicating each of the n energy spectrum data to determine the propagation direction of the interfering wave for each frequency. As a result, the cable number specified for each frequency spectrum is output.

[Embodiment 7] FIG. 18 is a diagram showing an example of the non-contact type voltage probe device of the present invention. Here, in FIG.
The same parts as those in (A) are designated by the same reference numerals.

In FIG. 18, reference numeral 201 denotes the cable 2
In order to detect the voltage applied to 20 in a non-contact manner, a non-contact electrode having a cylindrical inner electrode 201A that penetrates the cable 220 and a coaxial cylindrical outer electrode 201B that is coaxially arranged to surround the inner electrode 201A. is there. 20
Reference numeral 2 is a fixing jig made of an insulator for fixing the cable 220 inside the internal electrode 201A. 203
Is a high input impedance voltage probe that can be configured by a high input impedance voltage detection circuit that uses active elements (transistors).

By connecting the coaxial cylindrical external electrode 201B to the ground side of the high input impedance voltage probe 203 and having a connecting conductor wire or a connecting terminal 210 for grounding the coaxial cylindrical external electrode 201B, the cylindrical internal electrode 2
The change in the sensitivity of the probe due to the change in the electrostatic capacitance between 01A and the surrounding metal object 230 and the influence of the voltage of the peripheral cable 221 are suppressed. By interposing a low dielectric constant plastic or a foam material between the cylindrical inner electrode 201A and the coaxial cylindrical outer electrode 201B, the electrode 201A
And 201B, the capacitance can be reduced and the sensitivity of the probe can be improved.

In an environment in which the connection terminal 210 cannot be directly connected to the ground side, a metal plate is placed under the entire probe apparatus and the connection terminal 210 is connected to the metal plate.
As a result, the outer electrode 201B is connected to the ground side with a capacitance interposed.

Reference numeral 204 is a level meter. The level meter 204 may be an oscilloscope or the like as long as it is a device for measuring voltage. Alternatively, the measuring device 23 shown in FIG. 1 and the searching device shown in FIG. 11 can be used. The non-contact type voltage probe device shown in FIG. 18 includes a cable 220 and a cylindrical inner electrode 201A.
The change in the voltage transmitted through the cable 220 is extracted by the electrostatic coupling generated between the cable 220 and. Coaxial cylindrical external electrode 201B
Uses a conductor having a high conductivity, such as copper or aluminum.

Further, the jig 202 for fixing the cable 220 is made of an insulating material, and by keeping the distance between the cable 220 passing through the inside and the cylindrical internal electrode 201A constant, the internal electrode 201A and the cable The capacitance with 220 is made constant. Further, as the high input impedance voltage probe 203, when the one whose input impedance is represented by a parallel circuit of resistance and capacitance is used, almost flat characteristics can be obtained at the cutoff frequency or higher.

It is assumed that a voltage V is generated between the cable 220 passing through the inside of the cylindrical inner electrode 201A and the ground (indicated by the power source 205 in the figure). At this time, a coupling occurs between the cable 220 and the cylindrical internal electrode 201A by electrostatic coupling. The ratio of this coupling, that is, the capacitance C between the cable 220 and the cylindrical inner electrode 201A can be approximated by the following equation.

[0077]

[Equation 5]

Here, ε ₀ is the permittivity in vacuum, ε _r is the relative permittivity of the cable fixing jig 202, a is the outer diameter of the conductor of the cable 220 passing through the inside, and b is the cylindrical inner electrode 201.
Inner diameter of A, l is cylindrical internal electrodes 201A and 201B
Is the length of. The capacitance C _s between the cylindrical inner electrode 201A and the cylindrical outer electrode 201B is similarly approximated by the following equation.

[0079]

[Equation 6]

Here, c is the outer diameter of the cylindrical inner electrode 201A, d is the inner diameter of the cylindrical outer electrode 201B, and l is the length of the cylindrical electrodes 201A and 201B.

High Input Impedance Voltage Probe 203
If the input resistance R _p and the input capacitance are C _p , the non-contact type voltage probe device is represented by an equivalent circuit as shown in FIG. In FIG. 19, reference numeral 205 denotes a voltage source simulating the voltage V generated in the cable 220.
6 represents the capacitance C between the cable 220 and the cylindrical inner electrode 201A, and 207 represents the cylindrical inner electrode 2
The capacitance C _s between 01A and the cylindrical outer electrode 201B is shown.

Reference numerals 208 and 209 respectively denote the input resistance R _{p of the} high input impedance voltage probe 203.
And the input capacitance C _p . From this equivalent circuit, the output voltage measured by the level meter 204, that is, the voltage V _p across the terminals of R _p or C _p in the equivalent circuit is given by the following equation.

[0083]

[Equation 7]

In the frequency range where ωR _p (C + C _p ) >> 1, the output voltage V _p of the probe 203 is

[0085]

[Equation 8]

Therefore, it can be seen that the sensitivity is constant regardless of the frequency.

In the present invention, as compared with the conventional non-contact type voltage probe device, the cylindrical external electrode 201B is provided on the outside,
By grounding this, the influence from the outside can be eliminated. FIG. 17 (D) shows an equivalent circuit of the present invention corresponding to FIG. 17 (C) showing an equivalent circuit of a conventional non-contact type voltage probe device considering the influence of the surroundings. FIG. 17
The equivalent circuit of (D) is equivalent to the equivalent circuit of FIG. 19, and it can be seen that by grounding the cylindrical external electrode 201B, C _x , C _q , and V _x that are error factors can be removed.

[Embodiment 8] FIGS. 20A and 20B.
FIG. 1A is a plan view and a cross-sectional view, respectively, showing a schematic configuration of an embodiment of a non-contact voltage probe device according to the present invention.
21A and 21B show a- shown in FIG.
It is sectional drawing which cuts and shows by a'line.

20 (A) and (B), FIG. 21 (A)
In (B), 211 and 212 are two sets of semi-cylindrical electrode halves obtained by dividing the electrode structure shown in FIG. 18 in half, and these halves 211 and 212 are electrically and mechanically joined. As a result, the electrode structure shown in FIG. 18 is formed. Reference numeral 202 is a fixing jig made of a foam material for fixing the cable 220 passing through the inside of the internal electrode 201A. 213 is two semi-cylindrical electrodes 211 and 212
Is a metal fitting for fixing and in a cylindrical shape, and 214 is a metal fitting (hinge) for mechanically clamping and electrically connecting the two semi-cylindrical electrodes 211 and 212.

In the cylindrical inner electrode 201A, the coupling capacitance with the cable 220 to be measured is calculated by the equation (6). Also, the electrodes 201A and 20
The material of 1B is a copper plate in this embodiment, but it does not have to be copper as long as it has a large conductivity.

By using a material which is easily elastically deformed in the cable fixing jig 202, the cable 220 can be fixed near the center of the cylindrical internal electrode 201A regardless of the diameter of the cable 220 passing through the inside. . Further, as the material of the fixing jig 202, rubber sponge is used in the present embodiment, but other similar materials such as polyurethane can be used as long as they are foamable materials. Further, a leaf spring made of plastic may be used instead of the foamable material.

In FIG. 21 (B), a conducting wire 215 that withstands repeated bending is attached between the half-divided internal electrodes 201A as shown to ensure the electrical connection between the divided cylindrical electrodes 201A.

FIG. 22 is a diagram showing frequency characteristics of the non-contact type voltage probe device of the eighth embodiment. From this, 10 [k
It can be confirmed that the probe has a wide band with flat characteristics above [Hz].

[Ninth Embodiment] In the ninth embodiment, as shown in FIG. 23, a voltage detecting circuit 216 is attached to the cylindrical outer electrode 201B, and a voltage can be taken out from there by a coaxial connector 217 by a coaxial cable or the like. This is a non-contact type voltage probe device. The center conductor 217A of the coaxial connector 217 is connected to the electrode 201A, and the outer conductor 217B is connected.
Is connected to the electrode 201B. An amplifier may be provided in the voltage detection circuit 216. According to this embodiment, it is possible to reduce the parasitic inductance and capacitance generated in the ground wire or the like of the high input impedance probe in the high frequency region, and it is possible to realize a probe having a wide frequency characteristic.

As described above, the cylindrical outer electrode 201B is provided coaxially outside the cylindrical inner electrode 201A for performing electrostatic coupling with the cable 220.
By grounding 1B, it is possible to prevent the sensitivity of the probe 203 from changing due to a change in electrostatic capacitance between the cylindrical internal electrode 201A and the surrounding metal object 230 such as a reinforcing bar.
Further, when a voltage is generated in the peripheral cable 221 and the like, if the cylindrical internal electrode 201A is the only one, it is affected by the voltage of the peripheral cables other than the measurement target due to electrostatic coupling. This effect can be reduced by further providing.

In order to fix the distance between the internal electrode 201A and the external electrode 201B constant, a support material is inserted between them. However, if the dielectric constant of the material is high, the capacitance between the internal and external electrodes increases. However, there is a problem that sensitivity decreases.

Therefore, in order to improve the sensitivity of the probe, by using a plastic material or a foam material having a low dielectric constant as a supporting material between the inner electrode 201A and the outer electrode 201B, the capacitance between the inner and outer electrodes is increased. The problem is solved by suppressing the increase of the.

Next, in order to easily attach the non-contact type voltage probe device of the present invention to the cable 220 to be measured, the embodiment of FIGS. 20 to 23 has a divided electrode structure, but a movable part is provided. In that case, it is necessary to connect electrically and mechanically stable electrodes. To solve this problem,
A conductive wire 215, which has good flexibility and repeatability and is resistant to bending, is connected to the movable portion to reliably connect both electrodes 201A.

In order to obtain the same effect, the hinge 214
The semi-cylindrical electrodes 211 and 212 may be pressure bonded together. In addition, while reducing the error due to interference waves from the outside,
In order to reduce the capacitance of the portion of the probe 203 and increase the sensitivity, a high input impedance voltage detection circuit such as a FET may be attached to the coaxial cylindrical electrode instead of the high input impedance voltage probe 203.

According to Examples 7, 8 and 9, the voltage applied to the cable 220 is detected by electrostatic coupling determined by the size and distance between the cable 220 and the cylindrical inner electrode 201A, and its sensitivity is detected by the cable. It is determined by the coupling capacitance between 220 and the cylindrical inner electrode 201A, the capacitance between the cylindrical inner electrode 201A and the cylindrical outer electrode 201B, and the ratio of the input impedance of the voltage probe 203.

As described above, Examples 7, 8 and 9
According to this, by arranging the cylindrical electrodes so as to be coaxially doubled, it is possible to eliminate the influence of the surrounding metal body and the like, and it is possible to stably measure the voltage applied to the cable with good reproducibility. Moreover, since the voltage is measured in a non-contact manner, it is possible to measure the voltage generated in the cable conductor to be measured without damaging the cable or affecting service. Therefore, the present invention is effective for the measurement of conducted electromagnetic noise in the operating state.

[0102]

As described above, according to the present invention, by arranging the cylindrical electrodes so as to be doubled coaxially, the influence of the surrounding metal body can be eliminated, and the voltage applied to the cable can be stabilized. It is possible to measure with high reproducibility. Moreover, since the voltage is measured in a non-contact manner, it is possible to measure the voltage generated in the cable conductor to be measured without damaging the cable or affecting service. Therefore, the present invention is effective for the measurement of conducted electromagnetic noise in the operating state.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing a first embodiment of the present invention.

FIG. 2 is a configuration explanatory view showing an example of a more specific configuration of Example 1 of the present invention.

FIG. 3 is a characteristic diagram showing an example of the magnitude of voltage and current of each cable according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing an example of a result of calculating the energy of each cable of Example 1 of the present invention.

FIG. 5 is a configuration explanatory view showing a second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing an example of a method for directly obtaining energy according to the present invention.

FIG. 7 is a structural explanatory view showing a third embodiment of the present invention.

FIG. 8 is a flowchart showing a procedure of an interfering wave intrusion route identifying method according to the first embodiment of the present invention.

FIG. 9 is a flowchart showing a procedure of an interfering wave intrusion route identifying method according to the third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a usage pattern example according to the fourth embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 12 is a characteristic diagram showing an example of display of energy of an interfering wave according to the fourth embodiment of the present invention.

FIG. 13 is a flowchart showing an example of an energy calculation procedure according to the fifth embodiment of the present invention.

FIG. 14 is a flowchart showing an example of an energy calculation procedure according to the fifth embodiment of the present invention.

15 (A) to (J) are explanatory diagrams for different cases of combinations of energy magnitudes and directions in step S9 of FIG.

FIG. 16 is a flowchart showing an example of a determination procedure in the frequency domain according to the sixth embodiment of the present invention.

17A is a perspective view showing a configuration of a conventional non-contact type voltage probe device, FIGS. 17B and 17C are equivalent circuit diagrams of the voltage probe device shown in FIG. 17A, and FIG. It is an equivalent circuit schematic of the voltage probe apparatus by Example 7 of this invention shown in contrast with C).

FIG. 18 is a configuration diagram showing a non-contact type voltage probe device according to a seventh embodiment of the present invention.

19 is an equivalent circuit diagram of the voltage probe device shown in FIG.

20A and 20B are a sectional view and a front view, respectively, showing a non-contact type voltage probe device according to an eighth embodiment of the present invention.

21A and 21B are cross-sectional views taken along the line aa 'in FIG. 20B.

FIG. 22 is a characteristic diagram showing frequency characteristics of the eighth embodiment of the present invention.

23 (A) and 23 (B) are respectively a front view and a side view showing a configuration of a ninth embodiment of the present invention.

[Explanation of symbols]

1, 2 Electronic devices 3, 4, 5, 6, 7 Cables 8 Electromagnetic interference wave induction sources 9a to 9d Electromagnetic interference wave 10 Current probe 11 Voltage probe 12 Main device 13 of small communication device Application device 14, 15 Communication Terminal 16, 17, 18 Communication cable 19 Power cable 20 Acrylic plate 21 Copper plate 22 Interfering wave generator 23 Measuring instrument 24, 25, 26, 27 Vector voltmeter 28 Probe 29, 30, 31, 32 Electric power measuring instrument 101 Electromagnetic interference wave Search device 102 Probe device 103 Probe device 104 Cable 111 Measuring unit 112 Recording device 113 Computing unit 114 Display unit 115 CPU 201A Cylindrical internal electrode 201B Cylindrical external electrode 202 Fixing jig 203 High input impedance voltage probe 204 Level meter 205 Voltage source 206 Capacitance C 2 7 capacitance _C s 208 input resistance _R p 209 input capacitance _C p 210 connecting terminals 211 and 212 semicylindrical electrode 214 hinge 215 conductor 216 voltage detection circuit 217 connector 217A central conductor 217B outer conductor 220 cable 221 cable 230 around the metal objects

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Ideguchi             3-19-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan             Telegraph and Telephone Corporation F-term (reference) 2G025 AA10 AB07 AC04

Claims (6)

[Claims] 1. A cylindrical internal electrode, a coaxial cylindrical external electrode which is arranged coaxially around the internal electrode outside the internal electrode, and an internal electrode which is arranged inside the internal electrode and is not to be measured. A cable fixing member for penetrating and holding a cable; a high-input-impedance voltage detection means connected to the internal electrode; and a means for connecting the external electrode to the ground side of the voltage detection means. A means is attached to the external electrode so as to reduce parasitic inductance or capacitance in a high frequency region, and a low dielectric constant material is arranged between the internal electrode and the external electrode. apparatus. 2. The non-contact type voltage probe device according to claim 1, wherein a low dielectric constant plastic or a foam material is arranged between the internal electrode and the external electrode. 3. A two-piece semi-cylindrical shape in which the inner electrode, the outer electrode and the cable fixing member are integrally formed.
2. A structure comprising two halves, wherein the two halves can be electrically and mechanically coupled so that the cable can be sandwiched inside the cable fixing member. Alternatively, the non-contact type voltage probe device according to item 2. 4. The non-woven fabric according to claim 3, wherein the portions forming the internal electrode and the portions forming the external electrode in the two halves are connected to each other by a conductor wire that can withstand repeated bending. Contact voltage probe device. 5. The non-contact type voltage probe device according to claim 3, wherein the two halves are electrically and mechanically coupled by a hinge or an electrical contact. 6. The non-contact type voltage probe device according to claim 1, wherein the voltage detection means is a high input impedance voltage probe having an active element.