JP5777600B2 - Non-contact voltage measurement probe - Google Patents

Description

  The present invention relates to a non-contact voltage measuring probe that measures an AC voltage waveform applied between two wires without contacting the core wires in a non-contact manner.

  In recent years, from the viewpoint of efficient use of power and energy saving, HEMS (Home Energy Management System) has been installed to install power sensors in the homes of power consumers such as ordinary households and offices, and to make efficient use of power and remote control of electrical equipment. ) And smart grid technology for power grid control is being developed and studied. In general, power sensors used in HEMS and the like are installed on a distribution board in a home or individual home appliances. However, for accurate measurement of power consumption, current waveforms and voltage waveforms for at least one cycle of a commercial power supply are used. is necessary.

  As a means for measuring the current flowing through the power line in a non-contact manner, a current probe using the principle of a transformer and a current sensor using a magnetic detection element such as a Hall element are known and put into practical use as a sensor for HEMS. ing.

  On the other hand, in order to monitor the power between two wires, an accurate voltage waveform can be obtained if the voltage can be measured by directly touching the two power wires, but if you want to install a new sensor on an existing distribution board, etc. In order to carry out construction work that directly contacts the power line, it is necessary to be qualified as an electrician, or for safety, it is necessary to carry out construction work after stopping energization. There are large restrictions and burdens, which are barriers to sensor introduction.

  Actually, only the current value is monitored, and the voltage may be approximated by a sine wave to calculate the power. However, the voltage waveform of the commercial power supply is distorted and differs from the sine wave. In many cases, it is desirable to be able to detect at least the synchronization timing such as the zero-cross point of the voltage because the power waveform cannot be obtained unless the power is calculated in a form in which the current waveform is synchronized with the voltage waveform.

  In view of the above, there is a need for means capable of acquiring a voltage waveform without contact with a power supply line or the like.

  As a conventional means for measuring voltage without contact, a capacitive voltage probe (Non-Patent Document 1) using the principle of capacitive coupling is known. The capacitive voltage probe is a means suitable for measuring a common mode voltage (voltage generated between a target electric wire and the ground) superimposed on a power line or a communication line, and is used for measuring an interference wave related to EMC. It is used.

Kobayashi, Tajima, Hiroshima, Kuwabara, Hattori, “Development and Characteristics of Capacitive Voltage Probe”, The Institute of Electronics, Information and Communication Engineers, 1998, Technical Report of IEICE, EMCJ 98-25 (1998-06)

  However, this capacitive voltage probe has a problem that it is not in a form that can be applied to the use of measuring the voltage between two wires in a non-contact manner.

  In addition, as another means of measuring AC voltage in a non-contact manner, a reference voltage is calculated from the measurement result of the induced voltage detected using capacitive coupling, the reference voltage is fed back to the sensor, and the feedback gain is changed. A method for measuring a voltage value is known. Such a method reduces the variation in voltage measurement, but requires a reference voltage generation means and a feedback circuit using a variable capacitance circuit and an oscillation circuit, which increases the circuit scale and power consumption, and increases the sensor itself. There is a problem.

  In addition, there is a method in which a material whose optical characteristics change according to the electric field strength is arranged in the vicinity of the electric wire, and voltage measurement is performed using the characteristics of the light. There is a problem that costs increase.

  As described above, conventionally, there is no simple means for measuring an AC voltage waveform between two wires in a non-contact manner, which has hindered accurate sensing of power and safe measurement of high voltage.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a non-contact voltage measuring probe for measuring a voltage waveform between two wires with a simple non-contact sensor configuration. is there.

In order to solve the above-mentioned problem, the present invention is a non-contact voltage measuring probe for measuring an alternating voltage waveform applied between two electric wires, and is a cylindrical first electrode surrounding the first electric wire. A first electrode disposed so as not to be electrically connected to the first electric wire, and a cylindrical second electrode surrounding the second electric wire, wherein the second electric wire is A second electrode installed so as not to be electrically connected, a voltage measuring device for measuring a voltage between the first electrode and the second electrode, and a cylindrical shape surrounding the outside of the first electrode A first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode, and the first shield electrode and the second electrode. and means for electrically connecting the door, the voltage measured by the voltage measuring device, The voltage generated between the first electric wire and the second electric wire is a capacitance C1 between the first electric wire and the first electrode, and the second electric wire and the second electrode. And the input capacitance Cp of the voltage measuring instrument and the input impedance in which the input resistance Rp are connected in parallel are divided by a circuit connected in series. An AC voltage waveform between the first electric wire and the second electric wire is indirectly measured by detecting a voltage generated between the first electrode and the second electrode. To do.

The invention described in claim 2 is a non-contact voltage measuring probe for measuring an AC voltage waveform applied between two electric wires, and is a cylindrical first electrode surrounding the first electric wire. A first electrode installed so as not to be electrically connected to the first electric wire, and a cylindrical second electrode surrounding the second electric wire, wherein the second electric wire is electrically A second electrode placed so as not to be connected, a voltage measuring device for measuring a voltage between the first electrode and the second electrode, and a cylindrical first surrounding the outside of the first electrode A first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode, and a cylindrical second electrode surrounding an outer side of the second electrode Shield electrode installed so as not to be electrically connected to the second electric wire and the second electrode The second shield electrode, and means for electrically connecting the first shield electrode and the second shield electrode, and the voltage measured by the voltage measuring instrument is the first electric wire. Voltage generated between the second electric wire and the second electric wire is a capacitance C1 between the first electric wire and the first electrode, and a static voltage between the second electric wire and the second electrode. Based on the fact that the capacitance C2 and the input impedance in which the input capacitance Cp and the input resistance Rp of the voltage measuring instrument are connected in parallel are divided by a circuit connected in series, An AC voltage waveform between the first electric wire and the second electric wire is indirectly measured by detecting a voltage generated between the second electrode and the second electrode.

The invention described in claim 3 is a non-contact voltage measuring probe for measuring an alternating voltage applied between two electric wires, and is a cylindrical first electrode surrounding the first electric wire, A first electrode installed so as not to be electrically connected to the first electric wire, and a cylindrical second electrode surrounding the second electric wire, and electrically connected to the second electric wire A second electrode disposed so as not to be closed, and a cylindrical first shield electrode surrounding the first electrode so as not to be electrically connected to the first electric wire and the first electrode. And a cylindrical second shield electrode surrounding the outside of the second electrode so as not to be electrically connected to the second electric wire and the second electrode. A second shield electrode installed; the first shield electrode; and the second shield electrode. A first voltage measuring device for measuring a voltage between the first electrode and the first shield electrode, the second electrode, and the second shield electrode. A second voltage measuring device that measures a voltage between the first voltage measuring device and a difference between the voltage measured by the first voltage measuring device and the voltage measured by the second voltage measuring device. The voltage generated between the second electric wire and the second electric wire is a capacitance C1 between the first electric wire and the first electrode, and between the second electric wire and the second electrode. Capacitance C2, first input impedance Cp1 and input resistance Rp1 of the first voltage measuring instrument connected in parallel, input capacitance Cp2 and input resistance Rp2 of the second voltage measuring instrument A circuit in which a second input impedance connected in parallel is connected in series Thus based on the fact that the result obtained by dividing, characterized in that to indirectly measure the AC voltage waveform between said first wire and the second wire.

According to a fourth aspect of the present invention, in the non-contact voltage measurement probe according to the second or third aspect , the capacitance between the first electric wire and the first electrode is C10, and the first electrode Between the first electrode and the first shield electrode is C11, the capacitance between the second electric wire and the second electrode is C20, and the second electrode and the second shield electrode. When the capacitance between them is C21, they are configured to satisfy the relationship of C10 / C11 = C20 / C21.

According to a fifth aspect of the present invention, in the non-contact voltage measuring probe according to the third aspect , the voltage measuring device includes a buffer circuit configured such that the output impedance is lower than the input impedance. To do.

A sixth aspect of the present invention is the non-contact voltage measurement probe according to any one of the first to fifth aspects, further comprising a low-pass filter that removes a frequency component higher than a desired frequency band from the output signal of the voltage measuring device. It is characterized by that.
The invention according to claim 7 is a cylindrical first electrode surrounding the first electric wire, the first electrode installed so as not to be electrically connected to the first electric wire, and the second electrode A cylindrical second electrode surrounding the electric wire, the second electrode installed so as not to be electrically connected to the second electric wire, and the cylindrical first electrode surrounding the outside of the first electrode A first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode, and a cylindrical second electrode surrounding an outer side of the second electrode A second shield electrode installed so as not to be electrically connected to the second electric wire and the second electrode; and the first shield electrode and the second shield electrode are electrically connected And a voltage between the first electrode and the first shield electrode Using a non-contact voltage measuring probe comprising a first voltage measuring device for measuring and a second voltage measuring device for measuring a voltage between the second electrode and the second shield electrode, 2 A non-contact voltage measuring method for measuring an alternating voltage applied between wires of a wire, the difference between a voltage measured by the first voltage measuring instrument and a voltage measured by the second voltage measuring instrument However, the voltage generated between the first electric wire and the second electric wire is a capacitance C1 between the first electric wire and the first electrode, the second electric wire, and the second electric wire. A capacitance C2 between the first voltage measuring device, a first input impedance in which an input capacitance Cp1 and an input resistance Rp1 of the first voltage measuring device are connected in parallel, and an input capacitance Cp2 of the second voltage measuring device And a second input impedance in which an input resistor Rp2 is connected in parallel Doo is based on the fact that the result was divided by a circuit connected in series, characterized in that to indirectly measure the AC voltage waveform between said first wire and the second wire.

  The present invention has an effect of making it possible to measure a voltage waveform between two wires with a simple non-contact sensor configuration.

(A) is a schematic diagram of the basic composition of the non-contact voltage measurement probe concerning Embodiment 1 of the present invention, and (b) is a figure explaining the principle. It is a figure which shows the result of having measured the frequency characteristic of the non-contact voltage measuring probe which concerns on Embodiment 1 of this invention. It is a block diagram of the non-contact voltage measurement probe which concerns on Embodiment 2 of this invention. It is a figure which shows the equivalent circuit of the non-contact voltage measurement probe which concerns on Embodiment 2 of this invention. It is a block diagram of the non-contact voltage measurement probe which concerns on Embodiment 3 of this invention. It is a figure which shows the equivalent circuit of the non-contact voltage measurement probe which concerns on Embodiment 3 of this invention. It is a figure which shows the equivalent circuit simplified by abbreviate | omitting input resistance Rp, input capacity | capacitance Cp, and voltage source Vo of the non-contact voltage measurement probe which concerns on Embodiment 3 of this invention. It is a block diagram of the non-contact voltage measurement probe which concerns on Embodiment 4 of this invention. It is a figure which shows the equivalent circuit of the non-contact voltage measurement probe which concerns on Embodiment 4 of this invention. In the non-contact voltage measurement probe which concerns on Embodiment 4 of this invention, it is a block diagram which shows the structural example which improved the shielding effect of the whole system | strain using the shield cable. It is a block diagram of the non-contact voltage measurement probe which concerns on Embodiment 5 of this invention. It is a block diagram of the non-contact voltage measurement probe which concerns on Embodiment 6 of this invention.

  In order to solve the problems described above, in the non-contact voltage measurement probe of the present invention, two cylindrical electrodes installed so as to surround each of the two electric wires are used, and are generated between the electrodes. By measuring the electrostatic induction voltage, the AC voltage waveform applied between the wires is indirectly measured. Since measurement using electrostatic coupling is performed, measurement can be performed without electrical contact with the electric wire.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
FIG. 1A shows a schematic diagram of a basic configuration of a non-contact voltage measurement probe according to Embodiment 1 of the present invention, and FIG. 1B shows a diagram for explaining the principle thereof.

  As shown in FIG. 1A, the basic configuration of the non-contact voltage measuring probe of the present invention surrounds each of the two electric wires L1 and L2 to be measured, and the respective electric wires and the central axis substantially coincide with each other. The cylindrical electrode 101 and the electrode 102 are provided respectively. By measuring the voltage between the electrode 101 and the electrode 102 using the voltage measuring device 110, the line voltage Vo between the electric wire L1 and the electric wire L2 is indirectly measured.

  In general, these electric wires L1 and L2 are often covered with an insulator. In this case, the electric wires L1 and L2 are not in electrical contact with the electrodes 101 and 102. In order to prevent contact between the electrodes 101 and 102 and the electric wires L1 and L2, an insulator or a dielectric may be sandwiched as a spacer. When the dielectric is sandwiched, the values of the capacitances C1 and C2 are larger than when there is no dielectric, and the sensitivity is improved. Moreover, if the shape of these spacers is appropriately designed according to the electric wires L1 and L2, it becomes easy to fix the electric wires on the central axes of the electrodes 101 and 102.

  The electrode 101 and the electrode 102 are provided with a voltage measuring device 110 for measuring the voltage between them. As described above, it is desirable to increase the input impedance of the voltage measuring instrument 110 as much as possible in terms of improving sensitivity. As the voltage measuring device 110, an operational amplifier, a buffer amplifier, a measurement amplifier, or the like having a high input impedance can be used. The voltage measuring device 110 may display the read measured voltage value V as it is, or may output the voltage value or the analog / digital converted voltage value, and perform processing or display with a device connected to the subsequent stage. good.

  Although it is advantageous to provide the voltage measuring device 110 as close as possible to the electrode 101 and the electrode 102 in terms of preventing intrusion of external noise and improving sensitivity, a measurement cable is connected to the electrode 101 and the electrode 102, A voltage measurement function may be provided at a remote location, and measurement may be performed via a measurement cable. However, in this case, since the stray capacitance between the electrode 101 and the electrode 102 is increased by the measurement cable, leading to deterioration of sensitivity, it is necessary to devise the arrangement of the measurement cable so that the stray capacitance does not increase as much as possible.

  FIG. 1B is a cross-sectional view and an equivalent circuit of FIG. 1A, and C1 and C2 indicate the capacitance between the electric wire L1 and the electrode 101 and between the electric wire L2 and the electrode 102, respectively. Show. FIG. 1B shows the input capacitance of the voltage measuring instrument 110 as Cp and the input resistance as Rp.

  As shown in FIG. 1B, the line voltage Vo to be measured is applied to a circuit in which C1, the input impedance (Cp and Rp) of the voltage measuring device 110, and C2 are connected in series. Therefore, the measurement voltage V is obtained as a result of dividing Vo by these impedances.

It is expressed. Here, C12 is a combined capacity when C1 and C2 are connected in series. C12 = C1C2 / (C1 + C2)
Ω represents each frequency. (J is an imaginary unit)
From equation (1), as the input impedance of the voltage measuring instrument 110 increases, that is, as the input capacitance Cp decreases and the input resistance Rp increases, the denominator approaches the combined capacitance C12, and the measurement voltage V approaches the line voltage Vo. .

  Further, when the frequency of the voltage to be measured is high (when ω >> 1 / (Rp (C12 + Cp)), the expression (1) is

In the high frequency region, the voltage conversion sensitivity becomes a constant value that does not depend on the frequency.

  Actually, a non-contact voltage measurement probe having the configuration shown in FIG. 1A is prepared, and the frequency characteristics thereof are measured, and the result is shown in FIG. FIG. 2 also shows the result of calculation based on equation (1) when the parameters of capacitances C1 and C2, input capacitance Cp, and input resistance Rp are fitted. The amplitude characteristic in FIG. 2 shows the voltage conversion sensitivity. As described above, a flat amplitude frequency characteristic is obtained in a high-frequency region exceeding 10 kHz.

  As described above, the measured voltage V measured by the voltage measuring device 110 is substantially equal to the line voltage Vo when the input impedance of the voltage measuring device 110 is sufficiently high, and becomes the values of the capacitances C1 and C2. Regardless, the line voltage value Vo can be measured. In addition, even when the input impedance is not sufficiently high as described above, if the frequency is sufficiently high, the voltage sensitivity is almost constant regardless of the frequency, so there is no distortion. The voltage waveform can be measured.

  Even in a low frequency (50/60 Hz) region like a general commercial power source, if the frequency band is a narrow signal like a commercial power source, the voltage conversion sensitivity is lowered, but the voltage waveform and phase information are 1) It is obtained as a measurement voltage V according to the equation.

  In the measurement system having a high input impedance as described above, it is easy to pick up high-frequency noise generated outside, and the measurement result may be affected in a place with a lot of noise. In the non-contact voltage measurement probe of the present invention, a concentric cylindrical shield electrode is provided outside the electrodes 101 and 102, and the connection between the shield electrodes and the capacitance between the electrodes 101 and 102 are increased. By designing to a specific value, the influence of externally induced noise can be suppressed, and voltage waveform measurement with high accuracy is possible.

(Embodiment 2)
FIG. 3 shows a configuration diagram of a non-contact voltage measurement probe according to Embodiment 2 of the present invention. FIG. 4 shows an equivalent circuit of the non-contact voltage measurement probe according to Embodiment 2 of the present invention.

  In FIG. 3, a cylindrical shield electrode 103 is provided outside the cylindrical electrode 101 so that the central axis thereof coincides with the cylindrical electrode 101. The shield electrode 103 is not in electrical contact with either the electric wire L1 or the electrode 101, but is in electrical contact with the electrode 102 by an electric wire or the like. In addition, since it is desirable to fix the physical arrangement | positioning with the electrode 101 also to the electric wire L1, you may provide a spacer etc. in a gap | interval and may fix physically. The capacitance between the electrode 101 and the shield electrode 103 was αC1 using the capacitance C1 and the coefficient α.

  When measuring the voltage of a commercial power supply (single-phase three-wire) for general households, one side (cold side) of AC100V is grounded as a neutral point. In such a case, it is desirable to use the cold side as the electric wire L2. In addition, when a single line is connected to a circuit ground or the like, it is desirable to use the ground side as the electric wire L2. This is because the shield electrode 103 is installed to prevent the influence of external noise, particularly common mode noise, and since it is connected to the electrode 102, the lower the impedance of the electrode 102 with respect to the ground, the more noise is removed. This is because the effect becomes high.

  Note that one side of the voltage measuring device 110 may be connected to the shield electrode 103 or to the electrode 102 (dotted line in the figure).

FIG. 3 shows a conductor N in which a common mode noise voltage V _N is generated as a noise source. Conductor N is a noise source results in the influence of the noise by electrostatic induction, but the coupling capacitance between the FIG. 3 affects it conductor N and the shield electrode 103 and the C _N.

Noise voltage V _N of the common mode, when the common mode impedance to earth wire L1 and line L2 is high, because the common-mode impedance of the electrode 101 and the shield electrode 103 can be regarded as substantially equal, the noise voltage V _N and the electrode 101 shields The influence on the measurement voltage V which is the voltage between the electrodes 103 is small.

On the other hand, since one of the commercial power lines is grounded as described above (in this case, the electric wire L2), the common mode impedance of the electrode 102 is low, and the shield electrode 101 connected thereto is the same. Since the noise current due to the noise voltage V _N flows from the coupling capacitance C _N to the ground via C ₂ , the noise voltage V _N gives the measurement voltage V if the capacitance C 2 is sufficiently larger than the coupling capacitance C _N. The influence can be reduced. Note that, if possible, ideal noise shielding is possible if the electrode 102 is grounded or can be connected to the grounded electric wire L2.

(Embodiment 3)
Next, FIG. 5 shows a configuration diagram of a non-contact voltage measurement probe according to Embodiment 3 of the present invention. FIG. 6 shows an equivalent circuit of the non-contact voltage measurement probe according to Embodiment 3 of the present invention.

  In FIG. 5, in addition to the shield electrode 103 provided outside the cylindrical electrode 101 as in the second embodiment, the cylindrical shield is arranged outside the cylindrical electrode 102 so that the central axis thereof coincides with the shield electrode 103. An electrode 104 is provided. The shield electrode 104 is not in electrical contact with either the electric wire L2 or the electrode 102, but is in electrical contact with the shield electrode 103 with an electric wire or the like. The capacitance between the electrode 101 and the shield electrode 103 is α1C1 using the coefficient α1 and the capacitance C1, and the capacitance between the electrode 102 and the shield electrode 104 is α2C2 using the coefficient α2 and the capacitance C2. .

FIG. 5 shows a case where the common mode noise voltage V _N of the noise source N similar to the above affects via the coupling capacitor C _N. In this embodiment, the shield electrode 103 and the shield electrode 104 are electrically connected, and an equivalent circuit thereof is as shown in FIG.

In order to examine only the influence of the noise voltage V _N on the measurement voltage V in FIG. 6, the input equivalent circuit Rp, the input capacitance Cp, and the voltage source Vo are omitted from FIG. . In FIG. 7, voltages with respect to the ground caused by the noise voltage V _{N at} the electrode 101 and the electrode 102 are respectively indicated as V1 and V2. At this time,

Therefore, the measured voltage V is

It becomes. When α1 = α2, (5) formula V = 0, and the measured voltage V is not affected by the noise voltage _{V N.} From the above, the external noise can be canceled by designing the structure of the electrode and the shield electrode so that α1 = α2.

  In other words, in other words, α1 = α2, the capacitance between the wire L1 and the electrode 101 is C10, the capacitance between the electrode 101 and the shield electrode 103 is C11, and between the wire L2 and the electrode 102. When the capacitance between the electrode 102 and the shield electrode 104 is C21, and

It is the same as having the relationship.

(Embodiment 4)
Next, FIG. 8 shows a configuration diagram of a non-contact voltage measurement probe according to Embodiment 4 of the present invention. FIG. 9 shows an equivalent circuit of the non-contact voltage measurement probe according to Embodiment 4 of the present invention.

In FIG. 8, the electrode and the shield electrode are the same as in the third embodiment shown in FIG. 5, but two voltage measuring devices 113a and 113b are provided, and the voltage between the electrode 101 and the shield electrode 103 is provided by the voltage measuring device 113a. The voltage between the electrode 102 and the shield electrode 104 is measured by the voltage measuring device 113b. When the difference calculation device 130 sets the measurement results of the respective voltages to Vp1 and Vp2, the difference V = Vp1−Vp2
Is output as a measurement result.

  By dividing the voltage measuring devices 113a and 113b and the respective electric wires L1 and L2, the voltage between the adjacent electrodes and the shield electrode can be measured even when the distance between the two electric wires L1 and L2 is long. Therefore, it is possible to prevent the problem of easily picking up external noise by routing a high-impedance measurement cable between the wires.

  Further, if the shield electrode can be grounded as shown by the one-dot chain line in FIGS. 8 and 9, the shielding effect of the entire apparatus can be enhanced.

  FIG. 10 shows a configuration example in which the shielding effect of the entire system is enhanced using a shielded cable with such a configuration. A cylindrical shield electrode 104 is provided outside the cylindrical electrode 102 so that the central axis thereof coincides with the cylindrical electrode 102. The shield electrode 104 is not in electrical contact with either the electric wire L2 or the electrode 102, but is in electrical contact with the shield electrode 103 with an electric wire or the like. The capacitance between the electrode 101 and the shield electrode 103 is α1C1 using the coefficient α1 and the capacitance C1, and the capacitance between the electrode 102 and the shield electrode 104 is α2C2 using the coefficient α2 and the capacitance C2. .

  The electrode 101, the shield electrode 103 and the voltage measuring device 113a, and the electrode 102, the shield electrode 104 and the voltage measuring device 113b are connected by a shield cable 120, and the shield portion of the shield cable 120 is grounded. .

(Embodiment 5)
In FIG. 11, the block diagram of the non-contact voltage measurement probe which concerns on Embodiment 5 of this invention is shown.

  In FIG. 11, the voltage measuring devices 114a and 114b include an amplifier circuit or a buffer circuit that measures a voltage with a high input impedance and outputs the result with a low output impedance. The voltage measuring devices 114a and 114b measure the voltage by directly connecting the amplifier circuit or the buffer circuit to the electrodes 101 and 102 and the shield electrodes 103 and 104, respectively. The voltage measuring devices 114a and 114b and the difference calculating device 130 are connected by a low impedance transmission line.

  In the fifth embodiment, since the high impedance portion can be shortened as much as possible, it is difficult to pick up external noise. Further, since the output impedance is low, the measurement result can be sent using an inexpensive cable without a shield such as a pair cable.

(Embodiment 6)
In FIG. 12, the block diagram of the non-contact voltage measurement probe which concerns on Embodiment 6 of this invention is shown.

  In particular, when measuring a low-frequency voltage waveform such as an AC power supply voltage, the measurement system has a frequency characteristic as shown in FIG. In particular, it is easily affected by external high-frequency noise superimposed on the waveform, and noise and distortion may occur in the measured waveform. In such a case, in order to suppress the influence of the high frequency noise, it is close to the original waveform as shown in FIG. 12 by passing the low pass filter 140 having a function of removing a frequency component higher than a desired frequency band. Waveform can be played back.

  In addition, the diameters and lengths of the electrodes 101 and 102 in the present invention are not limited as long as electrostatic induction from the electric wires L1 and L2 can be detected with necessary and sufficient strength.

  As described above, by using the non-contact voltage probe of the present invention, it is possible to measure the voltage waveform of the power line, the communication signal voltage waveform, etc. without affecting the normal operation of the power line or the communication line. It can be measured without contact. In addition, it is possible to measure without special qualifications and skills because it is non-contact, even if it requires qualifications such as an electrician when performing measurement by electrical contact, or measurement of high voltage that is dangerous to measurement, etc. These monitors, monitoring and confirmation tests can be easily performed.

  In addition, since the non-contact voltage probe of the present invention has an effect of shielding or canceling external noise, it is difficult to be affected by external noise and enables highly accurate voltage measurement.

L1, L2 Electric wire 101, 102 Electrode 103, 104 Shield electrode 110-114 Voltage measuring device 120 Shield cable 130 Difference calculation device 140 Low pass filter

Claims (7)

A non-contact voltage measurement probe for measuring an alternating voltage waveform applied between two wires,
A cylindrical first electrode surrounding the first electric wire, the first electrode installed so as not to be electrically connected to the first electric wire;
A cylindrical second electrode surrounding the second electric wire, the second electrode installed so as not to be electrically connected to the second electric wire;
A voltage measuring device for measuring a voltage between the first electrode and the second electrode;
A first shield electrode having a cylindrical shape surrounding the outside of the first electrode, the first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode;
Means for electrically connecting the first shield electrode and the second electrode;
With
The voltage measured by the voltage measuring device is a voltage generated between the first electric wire and the second electric wire, and a capacitance C1 between the first electric wire and the first electrode; The capacitance C2 between the second electric wire and the second electrode and the input impedance in which the input capacitance Cp and the input resistance Rp of the voltage measuring device are connected in parallel are separated by a circuit connected in series. An AC voltage between the first electric wire and the second electric wire by detecting a voltage generated between the first electrode and the second electrode on the basis of the pressed result. A non-contact voltage measuring probe characterized by indirectly measuring a waveform.
A non-contact voltage measurement probe for measuring an alternating voltage waveform applied between two wires,
A cylindrical first electrode surrounding the first electric wire, the first electrode installed so as not to be electrically connected to the first electric wire;
A cylindrical second electrode surrounding the second electric wire, the second electrode installed so as not to be electrically connected to the second electric wire;
A voltage measuring device for measuring a voltage between the first electrode and the second electrode;
A first shield electrode having a cylindrical shape surrounding the outside of the first electrode, the first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode;
A second shield electrode having a cylindrical shape surrounding the outside of the second electrode, the second shield electrode installed so as not to be electrically connected to the second electric wire and the second electrode;
Means for electrically connecting the first shield electrode and the second shield electrode;
With
The voltage measured by the voltage measuring device is a voltage generated between the first electric wire and the second electric wire, and a capacitance C1 between the first electric wire and the first electrode; The capacitance C2 between the second electric wire and the second electrode and the input impedance in which the input capacitance Cp and the input resistance Rp of the voltage measuring device are connected in parallel are separated by a circuit connected in series. An AC voltage between the first electric wire and the second electric wire by detecting a voltage generated between the first electrode and the second electrode on the basis of the pressed result. A non-contact voltage measuring probe characterized by indirectly measuring a waveform.
A non-contact voltage measuring probe for measuring an alternating voltage applied between two wires,
A cylindrical first electrode surrounding the first electric wire, the first electrode installed so as not to be electrically connected to the first electric wire;
A cylindrical second electrode surrounding the second electric wire, the second electrode installed so as not to be electrically connected to the second electric wire;
A first shield electrode having a cylindrical shape surrounding the outside of the first electrode, the first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode;
A second shield electrode having a cylindrical shape surrounding the outside of the second electrode, the second shield electrode installed so as not to be electrically connected to the second electric wire and the second electrode;
Means for electrically connecting the first shield electrode and the second shield electrode;
A first voltage measuring device for measuring a voltage between the first electrode and the first shield electrode;
A second voltage measuring device for measuring a voltage between the second electrode and the second shield electrode;
With
The difference between the voltage measured by the first voltage measuring instrument and the voltage measured by the second voltage measuring instrument is the voltage generated between the first electric wire and the second electric wire. A capacitance C1 between the electric wire and the first electrode, a capacitance C2 between the second electric wire and the second electrode, an input capacitance Cp1 of the first voltage measuring device, and A first input impedance in which the input resistor Rp1 is connected in parallel and a second input impedance in which the input capacitor Cp2 and the input resistor Rp2 of the second voltage measuring device are connected in parallel are separated by a circuit connected in series. A non-contact voltage measuring probe that indirectly measures an alternating voltage waveform between the first electric wire and the second electric wire based on the pressed result.
The capacitance between the first wire and the first electrode is C10, the capacitance between the first electrode and the first shield electrode is C11, the second wire and the Assuming that the capacitance between the second electrode is C20 and the capacitance between the second electrode and the second shield electrode is C21, they are C10 / C11 = C20 / C21.
Non-contact voltage measurement probe according to claim 2 or 3, characterized in that it is configured to satisfy a relationship.
The non-contact voltage measuring probe according to claim 3 , wherein the voltage measuring device includes a buffer circuit configured such that an output impedance is lower than an input impedance.
Non-contact voltage measurement probe according to any one of claims 1 to 5, characterized in that a low-pass filter for removing frequency components higher than a desired frequency band from the output signal of the voltage measuring device.
A cylindrical first electrode surrounding the first electric wire, the first electrode installed so as not to be electrically connected to the first electric wire;
A cylindrical second electrode surrounding the second electric wire, the second electrode installed so as not to be electrically connected to the second electric wire;
A first shield electrode having a cylindrical shape surrounding the outside of the first electrode, the first shield electrode installed so as not to be electrically connected to the first electric wire and the first electrode;
A second shield electrode having a cylindrical shape surrounding the outside of the second electrode, the second shield electrode installed so as not to be electrically connected to the second electric wire and the second electrode;
Means for electrically connecting the first shield electrode and the second shield electrode;
A first voltage measuring device for measuring a voltage between the first electrode and the first shield electrode;
Using a non-contact voltage measuring probe comprising a second voltage measuring device for measuring a voltage between the second electrode and the second shield electrode,
A non-contact voltage measuring method for measuring an alternating voltage applied between two wires,
The difference between the voltage measured by the first voltage measuring instrument and the voltage measured by the second voltage measuring instrument is the voltage generated between the first electric wire and the second electric wire. A capacitance C1 between the electric wire and the first electrode, a capacitance C2 between the second electric wire and the second electrode, an input capacitance Cp1 of the first voltage measuring device, and A first input impedance in which the input resistor Rp1 is connected in parallel and a second input impedance in which the input capacitor Cp2 and the input resistor Rp2 of the second voltage measuring device are connected in parallel are separated by a circuit connected in series. A non-contact voltage measuring method characterized by indirectly measuring an AC voltage waveform between the first electric wire and the second electric wire based on the pressed result.

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