JPS63188773A - Voltage measuring instrument - Google Patents

Abstract

PURPOSE:To measure a high voltage with high accuracy by insulating an electric field detecting element from the high voltage which is charged to a measurement electrode. CONSTITUTION:The voltage to be measured is charged to measurement electrodes 7 and 14 and then an electric field operates on the electric field detecting element 16f arranged between the measurement electrodes 7 and 14. A circularly polarized wave in this element 16f becomes an elliptically polarized wave which has a large diameter in an electric field detection direction and a small diameter in a direction crossing said direction at right angles because of the electric field. The flatness of this elliptically polarized light wave is larger and smaller as the electric field is intenser and weaker respectively. For the purpose, the electric field intensity is found by detecting the level of the elliptically polarized wave in a specific direction and multiplied by a coefficient corresponding to the distance between the electrodes 7 and 14 to obtain a voltage value. Further, a dielectric interposed between the electrodes 7 and 14 and element 16f, so the element 16f has resistance to the high voltage, which is measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a voltage measuring instrument that optically detects an electric field and measures high voltage with high precision.

[Prior art]

As a device for measuring high voltage, for example, two
An electrostatic voltmeter is known in which a high voltage is applied between a pair of foil electrodes and the pointer is moved by one arm using the repulsive force of the foil electrodes.

Separately, for example, Utility Model Application Publication No. 59-106068, etc., utilizes the so-called Ponkels effect, in which when an electric field is applied, the refractive index tensor of a certain type of crystal changes in proportion to the electric field strength. Electric field detectors that optically measure intensity are known.

[Problem that the invention seeks to solve]

The electrostatic voltmeter mentioned above can measure high voltages of about 50 kV, but because it has a structure in which the pointer is driven by the repulsive force between opposing foil electrodes, it is difficult to obtain a high measurement volume, especially when vibration is applied. has problems such as increased measurement errors.

On the other hand, an electric field detector can obtain high measurement accuracy, but if it is placed in a space where an electric field is generated, the electric field strength in that space can be measured by U.
This method has a problem in that it cannot be used in applications where the voltage to be measured is directly applied to an electric field detector to measure the voltage.

Means for Solving Problem c] The present invention has been made in view of the above problem, and it applies the voltage to be measured directly and increases the applied voltage by using the Pockels effect. It is an object of the present invention to provide a small and lightweight voltage measuring device that can measure voltages with ease.

The voltage measuring device according to the present invention includes a measuring electrode arranged to apply a voltage to be measured, and a measuring electrode arranged between the measuring electrodes, and an incident elliptical polarized light wave is output as an elliptically polarized light wave by an electric field. a dielectric interposed between the measurement electrode and the electric field detection element, a light emitting part that emits light that should be incident on the electric field detection element, and a light emitting part that captures the light emitted by the electric field detection element. The photodetector converts photoelectrically and the signal obtained by the photodetector.
The measuring device is characterized by comprising a measuring device main body provided with a voltage measuring section that converts into voltage value information between the measuring electrodes.

(Operation) The circularly polarized light wave incident on the electric field detection element is transmitted through the electric field detection element.

When a voltage to be measured is applied to the measurement electrodes, an electric field acts on the electric field detection element disposed between the measurement electrodes. The circularly polarized light wave within this electric field detection element becomes an elliptically polarized light wave that has a large diameter in the electric field detection direction and a small diameter in the direction perpendicular to the electric field detection direction due to the electric field. The degree of flatness of this elliptically polarized light wave increases as the electric field strength increases, and decreases as the electric field strength weakens.The electric field strength can be determined by detecting the size of the elliptically polarized light wave in a specific direction, and the electric field strength can be adjusted to Multiply by a coefficient corresponding to the distance between the two to obtain the voltage value.

Since a dielectric material is interposed between the Ullll electrode electric field detection elements, the electric field detection elements can withstand high voltage and high voltage can be measured with high precision.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a sectional view showing a voltage measuring device according to the present invention that can measure up to 50 kV. In Fig. 1, for example, ceramic 7
Covers 2A and 2B made of a suitable insulator are screwed and attached to both axial ends of the cylindrical light-shielding tube 1 made of aluminum. A screw shaft 4 to which a spherical measuring terminal 3 is attached passes through the center of one lid 2A, and this screw shaft 4 is screwed onto the screw shaft 4 and extends inside and outside the lid 2A. It is fixed to the lid body 2A by a long napft 5 and a nut 6 located respectively. A threaded shaft 8 is screwed into the tip end of the long nut 5, and the screw shaft 8 projects from the center of a disk-shaped measuring electrode 7 whose circumferential surface is arcuate. A nut 9 is screwed onto this screw shaft 8, and by tightening this nut 9, the measuring electrode 7 can be fixed to the long nut 5, and the measuring electrode 7 is fixed to the lid 2A. A screw shaft 11 with a measuring terminal 10 of the same size and shape as the measuring terminal 3 is inserted through the center of the other lid body 2B, and this screw shaft 11 is fitted with the screw shaft 11. , is fixed to the lid body 2B by a nut 12 and a nano H3 located on the inside and outside of the lid body 2B, respectively. A measuring electrode 14 having the same size and shape as the measuring electrode 7 is screwed onto the tip of the screw shaft 11. This measuring electrode I4 is concentric with and facing the measuring electrode 7, and the facing surfaces are parallel to each other. Note that the diameters of the measurement electrodes 7 and 14 are both 3 cI! 1, and the distance between the opposing sides is selected to be 3 cm. Therefore, when electricity is applied to both measurement electrodes 7 and 14, measurement electrode 7 is placed between them.
, 14 are generated parallel to each other, and a uniform electric field is generated at the center of the measurement electrodes 7.14.

A narrow and short opening 1 is provided in the axial center of the light-shielding cylinder 1.
a is formed perpendicular to the axial direction of the light shielding cylinder 1. An electric field detection part support 15 having an electric field detection part 16 attached thereto is screwed and attached to this opening 1a. The electric field detection part support 15 and the electric field detection part I6 are constructed as shown in a perspective view in FIG. The electric field detection unit support 15 has a rectangular parallelepiped shape, and a side surface 15a on which the electric field detection unit 16 is located is formed in the shape of a 10-circular arc on the inner peripheral surface of the light-shielding cylinder 1, and the electric field around the electric field detection unit 16 is I try not to disturb it. This electric field detection part support body 15 is made of ceramic, for example,
Two optical fibers 16a and 16b each having a protective tube 16c fitted therethrough are passed through the electric field detection portion support 15.

Light-shielding protection tubes 16d and 16e are connected to the distal ends of the optical fibers 16a and 16b, and a lens system 21. polarizer 22,
A compensating plate 23 is provided, and an analyzer 25, which will be described later, is provided inside the other protective tube 16e. Furthermore, the protection tube 16d
.

An electric field detection element 16f made of crystal is integrally attached to the distal end side of the element 16e so as to straddle them.

The electric field detection element 16f is located approximately at the center of the measurement electrode 7.14 at the center between the opposed measurement electrodes 7 and 14 (see FIG. 1), and the electric field detection element 16F and the measurement electrode 7.14 are parallel to each other. They are facing each other. When the electric field detection element 16f is made of crystal, a dielectric material 17 made of polyurethane resin, for example, having a dielectric constant ε=3.5, which is approximately equal to the dielectric constant ε=4 of the crystal, is injected into the light-shielding cylinder l. Then, the measurement electrodes 7, 1
4 and an electric field output element 16f are molded. The mold made of this dielectric material 17 is made by, for example, removing one lid body 2A and injecting the dielectric material 17 through its opening, leaving only a depth that will be located inside the light-shielding cylinder l when the lid body 28 is attached. In this state, the lid 2A is attached to close the opening, and the injected dielectric 17 is cured.

FIG. 3 is a schematic diagram showing the electric field detection section and the main body of the measuring instrument. In FIG. 3, the light emitted by the light emitting section 20 of the measuring instrument main body 30 (having one linear component in a random direction) [FIG. 4 (see al)] is transmitted from the optical fiber 16a to the lens system 20.
1 and enters the polarizer 22.

The light incident on the polarizer 22 is linearly polarized here [see FIG. 4(b)], and the linearly polarized light is transferred to the compensator 23, for example, an n+% wavelength plate (n = 0.1.2 -')
The compensating plate 23
A right-angled isosceles triangular prism-shaped prism 24A is provided on the output side of the prism 2. The light incident on the IA is reflected at a right angle on the side surface 24m facing the right angle part. The light emitted from the other short side surface 24n forming the right angle portion of the prism 24A is made incident on the electric field detection element 16f made of crystal.

The electric field detection element 16f has both end faces canted perpendicularly to the Z-axis direction, that is, its long direction, and is a rectangular parallelepiped long in the Z-axis direction, and the circularly polarized light wave is transmitted to the electric field detection element 16f.
When it receives an electric field while transmitting in the Z-axis direction, it becomes an elliptically polarized wave [see Fig. 4 (d+)], and in that state, it rotates and travels toward the output side.The output side of the electric field detection element 16F , a right-angled isosceles triangular prism-shaped prism 24B,
The surfaces 24p on one short side forming the right angle portion are provided in contact with each other, and the light incident on the prism 24B is reflected by the surface 24Q facing the right angle portion. An analyzer 25 is provided in contact with the other short side surface 24r forming the right angle portion of the prism 24B, and the light emitted from the prism 24B is made to enter the analyzer 25.

The analyzer 25 reflects only polarized waves in one direction [Fig. 4(e)
1], this linearly polarized light wave is made incident on the optical fiber 16b. The light that has passed through the optical fiber 16b is sent to the light receiving section 26.
The voltage is captured and converted into an electrical signal by a charging conversion element, and the electrical signal is input to the voltage measuring section 27.

The voltage measurement unit 27 calculates a voltage value from a circuit that measures the amplitude of the incident light on the light receiving unit 26, a correlation coefficient between the intensity level of the incident light and the electric field intensity, and the electric field intensity based on the input electric signal. It is equipped with an arithmetic circuit that stores a correlation coefficient corresponding to the distance between the measurement electrodes. With this configuration, the voltage measurement unit 27 calculates the electric field strength P (kV/am) based on the intensity of the incident light at the light receiving unit 26, that is, the amplitude of the linearly polarized wave, from the input electric signal, and The voltage V (kν) to be measured, which is applied to the measurement electrodes, is calculated by PX3, which is obtained by multiplying the value of the distance between the measurement electrodes by a coefficient 3, and is displayed on a display section (not shown). There is. Further, the electric field detection element 16f is
The electric field detection element 16f is molded with the measurement electrode 7.14 using a dielectric material 17 made of polyurethane resin which has high insulation properties and has a dielectric constant substantially equal to that of the electric field detection element 16f. It is insulated from the applied high voltage, and no electric field disturbance or partial discharge occurs around the electric field element 16f, making it possible to measure high voltage with high accuracy.

Note that the length of the electric field detection element 16f in the Z-axis direction varies depending on the length, and the twist angle of the vibration plane of the polarized light varies.
The component in the shortest diameter direction is determined at . In other words,
The twist angle of the vibration plane of the polarized light between the input side end face and the output side end face of the elliptically polarized wave electric field detection element 16f is set to be an integral multiple of 90 degrees.

When measuring voltage with a voltage measuring instrument configured in this way, the light emitting part 20 emits light, and a high voltage is applied between the measurement terminals 3 and 3 without measurement. An equal electric field is generated between 7 and 14, and this electric field acts on the electric field detection element 16f. The light passing through the electric field detection element 16f becomes an elliptically polarized light wave according to the electric field strength while passing through the electric field detection element 16f. It is well known that the degree of flatness of this elliptically polarized light wave increases as the electric field strength increases, and decreases as the electric field strength decreases, and that there is a correlation with the strength of the electric field. Therefore, the shortest axis direction component of the elliptically polarized light wave is detected by the analyzer 25, the light is received by the light receiving section 26, the electric field strength is calculated based on the strength of the light, and the electric field strength is multiplied by a coefficient to generate a voltage. is measured.

In this voltage measuring instrument, the electric field detecting section 16 and the measuring instrument main body 30 are connected only by optical fibers 16a and 16b, so it is not induced by external electric or magnetic fields and is safe without the risk of electric shock. Can be measured. Therefore, high voltage can be optically measured with high precision, and the voltage measuring device is small and lightweight.

In addition, crystal is commonly used as a Pockels element.
Compared to SO, LNO, etc., its Pockels constant is one order of magnitude smaller. Since the present invention utilizes this characteristic inversely, it is possible to measure voltages as high as about 50 kV with good linearity.

Although the high voltage measuring device shown in this embodiment is capable of measuring up to 50 kV, it is of course possible to change the measurable voltage range as appropriate by changing the facing distance of the measuring electrodes.

Furthermore, although polyurethane resin was used as the dielectric material in this example, it is of course possible to use other resins having approximately the same dielectric constant, and instead of molding the measurement electrode and the electric field detection element, Needless to say, it may be placed in Furthermore, the measuring electrodes may be of any shape as long as they can generate an equal electric field between the opposing electrodes, and may be spherical or of any other shape.

On the other hand, when the material of the voltage increase detection element is other than crystal, an appropriate dielectric material having a dielectric constant approximately equal to that of the material is used. Further, if the dielectric material can be shielded from light by applying a light-shielding paint to its outer surface after curing, the door-end tube may not be used.

〔effect〕

As detailed above, in the present invention, a dielectric material is interposed between the measurement electrode and the electric field detection element for applying the voltage to be measured, so that the electric field detection element does not charge the measurement electrode. isolated from high voltages.

Therefore, the high voltage to be measured applied to the measurement electrode can be optically measured, and can be measured with high precision without being affected by mechanical vibrations at all. Furthermore, since the electric field detection section and the measuring device main body are separated, there is no risk of electric shock on the measuring device main body side. Furthermore, since the light detected by the electric field detection section is not affected by an external electromagnetic field while reaching the main body of the all meter, there is no possibility that the measurement density will decrease. Therefore, it is possible to measure high voltage with high precision, and has an excellent effect of providing a small and light voltage measuring device.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the voltage measuring device of the present invention, Fig. 2 is a perspective view of the electric field detection section, Fig. 3 is a schematic illustration of the electric field detection section and the main body of the perimeter, and Fig. 4 is the electric field detection section. FIG. 1... Light-shielding cylinder 7.14... Measuring electrode 16...
・Electric field detection unit 16a, 16b...Optical fiber 1
6f... Electric field detection element 20... Light emitting part 22...
・Polarizer 24A, 24B... Prism 25...
Analyzer patent Applicant Mitsubishi Cable Industries Co., Ltd. Agent Patent attorney Noboru Kono 3 Illustrations 4 Illustrations

Claims (1)

[Claims] 1. A measuring electrode arranged to apply a voltage to be measured;
an electric field detection element disposed between the measurement electrodes, from which an incident circularly polarized wave becomes an elliptical polarization wave due to an electric field and is emitted; and a dielectric interposed between the measurement electrodes and the electric field detection element. , a light emitting section that emits light to be incident on the electric field detection element, a light receiving section that captures and photoelectrically converts the light emitted by the electric field detection element, and a signal obtained by the light receiving section that is converted into voltage value information between the measurement electrodes. A voltage measuring device comprising: a measuring device main body provided with a voltage measuring section. 2. The voltage measuring device as set forth in claim 1, wherein the measuring electrode has a shape to form a uniform electric field in the area where the electric field detection element is disposed. 3. The voltage measuring device according to claim 1, wherein the dielectric constant has a substantially equal dielectric constant to that of the electric field detection element.